A
Access Card:
A coded employee card, usually the size of a credit card, recognizable to the access control system and read by a reader to allow access. It can be used for photo identification of the cardholder and for other data collection purposes. Card technologies include magnetic strips, wiegand-effect, proximity (active/passive), barium ferrite, and smart/intelligent cards.
Access Code:
Any system or method which automatically controls the passage of people and vehicles into or out of an area or structure.
Access Control
The means of influencing and regulating the flow of persons through a door (entry and/or exit).
Access Level:
The door or combination of doors and/or barriers an individual is authorized to pass through.
Access Mask:
Electronic alarm masking suppresses the annunciation of an alarm condition that would have been reported in the “secure” mode of operation. Masking does not block the reporting ability of tamper or fault conditions that may not be seen when alarm shunting is used.
Access Point:
Each means of entry into a controlled security area, consisting of a card reader, monitor switches and/or latches. Access points are wired to an access control panel.
Access Relay:
An electrically operated switch that is activated when access is granted to unlock a door.
Annunciator:
An audible and/or visual signalling device.
Anti-Passback (Anti-Tailgating):
This feature protects against more than one person using the same card or number. It defines each system card reader and card I.D. number as IN, OUT, or Other. Once a card is granted access to and IN reader, it must be presented to an OUT reader before another IN reader access is granted. Cards will continue to have access to all authorized OTHER readers.
Access Time:
The period of time during which an access point is unlocked. (Also see shunt time).
Active Leaf
The leaf that opens first, in a pair of doors, and the one to which the lock is applied.
Actuator
The mechanism of the switch or switch enclosure that operates the contacts.
American National Standards Institute (ANSI)
A federation of trade, technical, and professional organizations, government agencies.
Ampere/Hour (AH)
A measurement of a battery’s capacity. One ampere of current flowing for one hour equals one ampere/hour.
Audit Trail:
A listing created which may be created in real time which may be used to monitor the progress of a person through protected areas.
Automatic Closing Door
Doors that normally are open but that close when the automatic-closing device is activated.
Architectural Hardware (Builders’ Hardware)
Term applied to all hardware used in building construction, particularly that used on or in connection with doors, frames, windows, and other movable members.
Astragal
A molding or strip whose purpose is to cover or close the gap between the meeting edges on a pair of doors. Some types overlap, others meet at the center line of the gap (split).
B
Badge:
To use a card key in a reader to gain access to protected areas; a card key itself, especially one with a photo I.D.
Battery Standby
A means of automatically switching over to stored battery power during local primary power failure.
Biometrics:
Refers to readers that identify human attributes such as fingerprint, hand geometry, voice recognition or retinal analysis.
Builder’s Hardware Manufacturers Association (BHMA)
The trade association for North American manufacturers of commercial builders hardware.
Block Diagram
A drawing that shows the relationship of equipment in a system. Blocks used to represent each piece of equipment are arranged into a system diagram that shows their physical or operational relation to each other.
Bolt
The projectable member of a lock or latch mechanism that engages the door frame and the strike. (See deadbolt and latchbolt.)
Bolt Position Switch
A miniature switch used on or in a locking device to monitor whether the locking bolt is in the locked (projected) or unlocked (retracted) position.
Bridge Rectifier
a circuit using four diodes to provide full wave rectification converting AC voltage to a pulsating DC voltage
Buffer Capacity:
Refers to the amount of information the system can store, this may include the users, time of day and specific door.
Buzzer
an electric signaling device that makes a buzzing sound
C
Code
A standard that is an extensive compilation of provisions covering broad subject matter or that is suitable for adoption into law independently of other codes and standards.
Coordinator
A device used on pairs of swinging doors that prevents the active leaf from closing before the inactive leaf closes. Necessary when an overlapping astragal is present and automatic or self-latching flushbolts are used with door closers on both leaves.
Cam
A rotating eccentric piece attached to the end of a cylinder plug to actuate a lock or latch mechanism.
Case
A housing for a lock mechanism.
Circuit
The path through which electrical energy flows.
Coded Card
A plastic card that has a combination (three to six digits, encrypted in its design either in a series of small magnets or on magnetic tape. Coil, electric - Successive turns of insulated wire that create a magnetic field when an electric current is passed through them.
Coercivity:
The property of a magnetic material, as on a magnetic stripe keys, which is a measure of the coercive force. It is used when describing the strength of magnetic saturation when discussing magnetic stripe card keys
Conductor
Material with the ability to carry electric current. The term is also used for an electric wire.
Connector
Generally, any device used to provide rapid connect/disconnect service for electrical cable and wire terminations.
Continuity
The state of belief, complete and uninterrupted, like a normally closed circuit.
Continuity Check
A test performed on a length of wire or cable to determine whether the electrical current flows continuously throughout the length.
Continuous Duty
Refers to a device or a control that can operate continuously with no off or rest periods.
Control Box
A sheet metal enclosure that contains electronic and electromechanical controls and circuitry.
Current
The flow of electrons through an electrical conductor. Current is measured in amperes.
Cylindrical Lock (Bored Lock)
Term used to describe locks or latches which have a cylindrical case into which a separate latch bolt case fits. Lock or latch
Cylinder
A housing that contains a tumbler mechanism and a key-way plug that can be turned only by the correct key. It includes a cam or spindle to transmit rotary action to a lock or latch mechanism. For security and keying versatility, authorities generally specify a pin-tumbler cylinder of no fewer than five pins. The two types of cylinders, the mortise cylinder (round, threaded housing) and the bored lock cylinder (sometimes called a cylinder insert), which both provide the same functional value of security and convenience and are often included in the same keying system. (See keying.) parts are intended for installation into a hole bored into the face of the door.
D
Database:
A collection of data used and produced by a computer program. The files created at the host of the access control system forms its database.
Deadbolt
A bolt operated manually and not actuated by springs. When locked, the bolt cannot be forced back. A deadbolt is operated (projected and retracted) by a key cylinder or lever handle.
Deadlatch
A latch in which the latchbolt is positively held in the projected position by an auxiliary mechanism.
De-energize
To remove power.
Delay
A period of time before or during an event.
Device Address:
alue set on an access control device to determine its unique identity.
Distributed Intelligent Devices:
Access control devices that make their own access decisions uploading event messages periodically to the central processing unit for storage.
Dogging Device
As used on exit devices, a mechanism that fastens the cross bar in the fully depressed position, and also retains the latch bolt or bolts in a retraction position thus permitting free operation of the door from either side. Not allowed on fire exit hardware.
Door Closer
A labeled device that, where applied to a door and frame, causes an open door to close by mechanical force. The closing speed can be regulated by this device.
Door Holder/Release Device
A labeled, fail safe device, controlled by a detection device, used on an automatic-closing door to release the door at the time of fire.
Door Status Switch
A DSS is a switch used to monitor whether a door is in an opened or closed position.
Double Pole, Double Throw (DPDT)
A term used to describe a switch or relay output contact form (2 form C) in which two separate switches are operating simultaneously, each with a normally open and normally closed contact and a common connection. This form is used to make and break two separate circuits.
Dry contact
Metallic points making (shorting) or breaking (opening) a circuit. The switched circuit must have its own source of power and is merely routed through the dry contacts.
Duty Cycle
The percentage of on time or operating time of a device. For example, a device that is on for one minute and off for nine minutes is operating at a 10 Percent duty cycle.
Door Holder/Release Device
A labeled, fail safe device, controlled by a detection device, used on an automatic-closing door to release the door at the time of fire.
Door Open Time:
The time allowed for a controlled door to remain open after a valid entry. At the expiration of this time, the system records a transaction which may be defined as an alarm. If the alarm bypass relay is used, it would also de-energize at the end of this time.
E
Egress:
Exit, depart, leave (opposite of ingress).
Egress Side
The side of an opening from which traffic exits.
Electric Strike
An electro-mechanical door locking device (usually solenoid-operated) that will unlock the door when electrical power is applied to it. A fail-safe configuration will operate in the reverse condition (i.e., normally locked when power is applied and unlocked when power is interrupted).
Electromagnet
A coil of wire, usually wound on an iron core, that produces a strong magnetic field when current is sent through the coil.
Electromagnetic:
Pertaining to combined electric & magnetic fields associated with movements of electrons through conductors
Electromotive force (EMF)
Pressure or voltage; the force that causes current to flow in a circuit.
Emergency Release
An optional feature of a lock that provides a means of overriding the lock and retracting the bolt in an emergency. It can be operated either mechanicallv or electrically.
Energize
To apply power.
Enclosure:
A box or cabinet, usually constructed of metal, that houses system components, such as circuit boards and other electronic and electrochemical controls and circuitry.
Erasable Programmable Read-Only Memory (EPROM):
A programmed memory (often in a chip) that can not only be read, but can be repeatedly erased under high-intensity ultraviolet light and reprogrammed.
Executive Privilege:
An option which allows a cardholder unlimited access to all operational access points. Access may be without the system referring to any other access parameters, or there may be a PIN-code requirement has been enabled.
Exit
That portion of a means of egress that is separated from all other spaces of a building or structure by construction or equipment as required to provide a protected way of travel to the exit discharge.
Exit Access
That portion of a means of egress that leads to an exit.
Exit Discharge
That portion of a means of egress between termination of an exit and the public way.
Exit Switch:
A push button, switch mat, proximity detector, or other device which starts a timer in the reader interface electronics when someone is leaving through a controlled entry or exit. The timer bypass (shunts) the door-open detector for a selected period of time.
F
Facility Code:
A numeric code programmed into a cardreader and encoded on the access card/token which is unique to the one card access systems facility. In a distributed or semi-distributed intelligent card reader system, the facility code will allow access to cardholders with the proper facility code when communications are lost with the CPU.
Fail Safe
Lock or locking device that remains unlocked on loss of power.
Fail Secure
Lock or locking device that remains locked on loss of power. Also known as Non-Fail Safe (NFS).
Fail-Unlocked:
An electric lock that automatically unlocks with any power interruption. Also called fail-safe.
Finish Hardware
Architectural or Builders Hardware that has a finished appearance as well as a functional purpose and that may be considered a part of the decorative treatment of a room or building.
Fire Door Assembly
Any combination of a fire door, a frame, hardware, and other accessories that together provide a specific degree of fire protection to the opening.
Fire Exit Hardware
Labeled devices for swinging fire doors installed to facilitate safe egress of persons and generally consisting of a cross bar and various types of latch release mechanisms that cannot be held in a retracted locked position and providing fire protection where used as part of a fire door assembly.
Fire Rating
The time, in minutes or hours, that materials or assemblies have withstood a fire exposure as established in accordance with the test procedures of NFPA 251.
Flush Bolts, Automatic
A mortised bolt installed near the top or bottom of the inactive leaf of a pair of doors that holds the inactive leaf in a closed position until the active leaf is opened.
Flush Bolts, Manual
A mortised bolt installed near the top or bottom of the inactive leaf of a pair of doors in which the bolts are manually extended or retracted into or out of the header or sill by a means of a lever.
G
Global Linking:
An input at one Access Control panel effecting the output at another
Ground
A conducting connection between an electrical circuit and the earth or other large conducting body to serve as an electrical ground, thus making a complete electrical circuit.
Ground, Earth
The portion (if a circuit that is connected to a buried metallic object such as a grounding rod or water pipe.
Guard Tour:
A defined route of a security guard.
H
Handing of Door
The description of swinging door operation, always viewed from outside the room, building, and so forth. Left hand means that the door hinges on the left and right hand means that the door hinges on the right.
Hard-Wired
Refers to groups of connections that require the use of wire conductors.
Heat Sink
A method used to transfer a rise in temperature by means of a metal plate or fin-shaped object with good heat transfer efficiency that helps dissipate heat into the surrounding air, into a liquid, or into a larger mass.
Hertz (Hz)
The international unit of frequency equal to one cycle per second.
HES
manufacturer of the best electro-mechanical access control devices in the world!
History:
A log of system activity that can be recalled by utilizing the report command. Most systems offer a feature that notifies the console operator of the amount of available storage for history information preventing information from being written over. The message will usually alert the operator to archive the information onto a removable magnetic tape.
Hot
Connected, alive, energized.
Humidity
The amount of moisture in the air, measured in percent of relative humidity.
I
Impedance
The opposition in an electrical circuit to the flow of an alternating current (AC). Symbol Z
Inactive Leaf
One door of a pair of doors that ordinarily is latched closed; the second operating door of a pair.
Induction
An influence exerted by a charged body or by a magnetic field on neighboring bodies without apparent communication; electrifying, magnetizing, or inducing voltage by exposure to a field.
Ingress:
Enter (opposite of egress).
Ingress Side
The side of an opening from which traffic enters.
Input Voltage
The designed power source requirement needed by equipment in order to operate properly.
Inrush
The initial surge of current through a load when power is first applied. Lamp loads, inductive motors, solenoids, and capacitive load types all have inrush or surge currents higher than the normal running or steady state currents..
Insulation
A material that provides high electric resistance, making it suitable for covering components, terminals, and wires to prevent possible future contact of adjacent conductors, resulting in a short circuit.
Interlock
A system of multiple doors with controlled interaction. Interlocks are also known as lightraps, airtraps, mantraps, and sallyports. (See safety interlock, security interlock.)
Intermittent Duty Solenoid
A solenoid designed to be energized for short periods of time. Continuous operation may damage an intermittent duty solenoid.
Isolation
No electrical connection between two or more circuits.
J
Jumper
A short length of conductor used to make a connection between terminals, around a break in a circuit, or around an instrument. It is usually a temporary connection.
Junction
A point in a circuit where two or more wires are connected.
Junction Box
A protective enclosure for connecting circuit wires
K
Key Switch:
A switch which must be operated with a key.
Keying
The various keying arrangements for pin-tumbler cylinders: individual key-the key for an individual cylinder; keyed alike-all cylinders may be operated by the same key (not to be confused with master keyed); keyed different-a different individual key operates each cylinder (or group of cylinders); master key-a key to operate a group of cylinders, each of which may be set to a different individual key; master keyed-all cylinders in a group can be operated by one master key, although all cylinders may be keyed differently (not to be confused with keyed alike).
Keypad:
A flat device which has buttons that may be pressed in a sequence to send data to a controller, and which differs (said to be “non-QUERTY”) from a typewriter-like computer board.
L
Labeled
Equipment or materials to which has been attached a label, symbol, or other identifying mark of an organization that is acceptable to the AHJ and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials, and whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.
Latch
The locking in of a circuit by means of a holding contact; used in relay logic when a momentary initiation is required.
Latchbolt
A device for automatically retaining a door in the closed position upon its closing; a beveled spring-loaded bolt that automatically seats in the strike on contact. Retracted by key cylinder or lever handle.
LCD:
An acronym for Liquid Crystal Display.
LED:
An acronym for Light-Emitting Diode.
Light-Emitting Diode (LED)
A diode, a solid-state device, that gives off virtually heatless colored light when electric current is passed through it. LEDs are very efficient and long-lasting.
Listed
Refers to equipment or materials included in a list published by an authorizing organization. The listing states that the equipment or material meets appropriate standards or has been tested for and is suited to a specific application.
Load
Any device that consumes electrical power; the amount of power required for operation of a circuit or device.
Load Rating
A control specification outlining the type of load, the minimum (min.) and the maximum (max.) currents, and the voltage. local alarm A visual or audible signaling device located at a monitored door, window, or other opening.
Lock
A device for securing a door in the closed position against unauthorized or forced entry. It requires actuation to project or to retract its bolt.
Labeled Product
Generally refers to products that may be used on a Fire Rated Opening.
Leaf
One of the two doors forming a pair of doors. Leaves are identified as being both active or as an inactive and an active leaf.
M
Magnetic Stripe:
A band of ferrous material that is sealed onto or into a card key or credit card.
Mantrap
See interlock.
Maximum Rating
The absolute maximum condition in which a device is designed to operate. Voltage, frequency, current, temperature, humidity, shock, and other parameters can be specified as maximum.
Means of Egress
A continuous and unobstructed way of travel from any point in a building or structure to a public way consisting of three separate and distinct parts: the exit access, the exit and the exit discharge.
Metal Oxide Varistor (MOV)
A device designed to protect electric equipment from high-transient voltage by diverting a momentary overvoltage to the ground. An MOV allows the overvoltage to dissipate, and then to restore itself to its initial non-conducting state.
Mode of Operation
The specified operational condition of a switch, lock, door system, and so forth,
Modem:
Device that converts the computer system’s digital information into analog information and transmits it over a telephone line. Another modem must be used when the information is received to convert the information back from analog to digital.
Momentary Switch
A spring-loaded contact that, when pressed, closes two contacts. When pressure is removed, the contacts open.
Monitoring Loop
A continuous loop of wire starting at the control panel and running through switches in a system to indicate a breach of security through an open switch or a cut wire.
Multi-conductor Cable
A cable consisting of two or more conductors, either cabled or laid in a flat parallel construction, with or without a common overall covering.
Multiplex
Refers to a system of transmitting several messages simultaneously on the same circuit or channel. Multiplex equipment greatly reduces the number of wire cables needed in a system.
Mortise Lock
Term used to describe locks or latches designed to be installed into a mortise pocket in the edge of door rather than applied to or through a hole bored in the face of a door.
Mullion
A fixed or removable vertical post set in a double door opening that allows both leaves to be active or set between a door and a side light or a separate, framed, glazed area.
N
National Electrical Code (NEC)
A standard for the safe installation of electrical wiring and equipment. It is part of the National Fire Codes series published by the NFPA.
National Fire Protection Association (NFPA)
The premier source worldwide for the development, publication and dissemination of knowledge about fire and life safety.
National Electrical Manufacturers Association (NEMA)
An organization known for its standardization of wire and cable specifications.
Noise
Unwanted and/or unintelligible signals picked up on a cable circuit.
Normally Closed (NC)
The condition or position of a contact prior to initiation or energization-in this case, a closed condition.
Normally Open (NO)
The condition or position of a contact prior to initiation or energization-in this case, an open condition.
O
Occupancy
The purpose for which a building or portion thereof is used or intended to be used.
Ohm
A unit of measurement for resistance (R) and impedance (Z).
Ohm’s Law
One of the most widely used principles of electricity. It expresses the relationship between voltage (E), current (I) and resistance (R) according to the following equations: E = IR; I = E/R; R = E/I.
Operating Temperature
A temperature range over which a device will perform within its specified design tolerances; may be stated in degrees Fahrenheit (‘F) or degrees centigrade (C).
Operating Voltage
The voltage by which a system operates; a nominal voltage with a specified tolerance applied; the design voltage range necessary to remain within the operating tolerances. For example, for a system specified 12 volts +/- 10 percent of nominal, 12 volts is the nominal voltage and the design voltage range is 10.8 to 13.2 volts DC.
Output Relays:
The auxiliary relays found in access control panels or NODES that control external devices.
Output Voltage
The designed power source produced by a power supply to operate equipment.
P
Panic Bar:
A device, usually a small electrical switch in a mounting plate, used for unlocking a door in a emergency.
Panic Exit Hardware
Non-fire labeled devices for swinging doors installed to facilitate safe egress of persons and generally consisting of a cross bar and various types of latch release mechanisms that can be held In a retracted locked position (dogged).
Parallel
A method of connecting an electric circuit whereby each element is connected across the other. The addition of all currents through each element equals the total current of the circuit.
Parking Gate:
A barrier that can be opened or closed to control vehicular access
Passive Infrared (PIR) Detector:
A sensor which detects the changes in the infrared light radiating from
Polarity
The positive or negative orientation of a signal or power source.
Potentiometer (POT)
Variable resistor.
Power Operated Fire Doors
Doors that normally are opened and closed electrically, pneumatically, or mechanically.
Primary
The transformer winding that receives the energy from a supply circuit.
Pullman Latch
type of latch which pivots like a hinge and whose locking side is radiused
R
Rated Voltage
The maximum voltage at which an electric component can operate for extended period, without undue degradation or safety hazard.
Reactance
Opposition offered to the flow of alternating current by inductance (xl) or capacitance (xc) of a component or circuit.
Reader:
Refers to the “front end” that a user must interact with to allow access. Readers can be keypads, card readers, proximity readers.
Rectifier
A solid state electrical device that will allow current to flow in one direction only. It is designed to convert alternating current to direct current.
Regulated Power Supply
A power supply that provides a constant output regardless of input voltage.
Relay
An electrically controlled device that opens and closes electrical contacts to effect the operation of other devices in the same or another electrical circuit.
Reset Time
The time required to return the output to its original condition.
Resistance
The opposition to the flow of an electric current (measured in ohms); the reciprocal of conductance.
Resistor
A circuit element whose chief purpose is to oppose the flow of current.
Rim Exit Device
a mechanical lock applied to the surface of the door that is operated from the inside of an outward swing door through the use of a crossbar or push rail extending at least halfway across the width of the door
Riser Diagram
A document which explains wire type, size, and the number of conductors to be run from a control panel to each control or monitor location.
S
Secured Side
Refers to the area or side of an opening that is locked, requires a key, card, code, etc. to enter.
Secondary
The transformer winding that receives energy by electromagnetic induction from the primary.
Self-Closing Doors
Doors that, when opened and released, return to the closed position.
Series Circuit
An electrical circuit in which all the receptive devices are arranged in succession, as distinguished from a parallel circuit. The same current flows through each part of the circuit in sequence.
Shall
Indicates a mandatory requirement.
Short
An improper connection between “hot” current-carrying wire and neutral or ground.
Should
Indicates a recommendation or that which is advised but not required.
Shunt:
To bypass. When an alarm is bypassed so that it doesn’t activate, it is said to be shunted.
Shunt Time :
The time in seconds that a door-open alarm is suppressed after the door has been opened.
Single Pole, Double Throw (SPDT)
A term used to describe a switch or relay contact form (1 form C) that has a normally open and a normally closed contact with a common connection.
Single Pole, Single Throw (SPST)
A switch with only one moving and one stationary contact, available either normally open (NO) or normally closed (NC).
Solenoid
An electromechanical device that operates the lock-bolt. When electricity is applied, a mechanical motion is obtained that moves the bolt.
Spike
A momentary increase in electrical current. Spikes can damage electronic equipment.
Splice
A connection of two or more conductors or cables to provide good mechanical strength as well as good conductivity.
Springlatch
A plain latch with a beveled latch-bolt that is activated by springs.
Standalone:
An access control system that makes its own access decisions without communicating with a central controller.
Strike:
A plate mortised into or mounted on the door jamb to accept and restrain a bolt when the door is closed. In some metal installations or with a deadlock, the strike may simply be an opening cut into the jamb. (Synonym: keeper)
Strike Plate:
A plate, usually of metal, mortised into or mounted on the door jamb to accept and restrain a bolt when the door is closed.
Switches
Devices that make or break connections in an electrical or electronic circuit. In computing systems, they are also used to make selections (the toggle switch, for example, completes a conditional jump). Switches are usually manually operated but can also work by mechanical, thermal, electromechanical, barometric, hydraulic, or gravitational means.
T
Terminal/Termination Block
A device that provides a place for safe and convenient interconnection of current-carrying conductors.
Terminals
Metal wire termination devices designed to handle one or more conductors and to be attached to a board, bus, or block with mechanical fasteners or clipped on. Common types are ring tongue, spade, flag, hook, blade, quick-connect, offset, flanged. Special types include taper pin, taper tab, and others, insulated and not insulated.
Throw
Measurement of the maximum projection of a deadbolt or latch bolt when the bolt is fully projected.
Time and Attendance:
The ability to utilize the time in and time out information per user, for the purpose of keeping track of employee’s hours at a facility. Many time and attendance packages work as stand-alone systems, and interface with most payroll software.
Time Delay
An electronically controlled delay period designed into a component that will either send a prolonged signal or delay transmitting a signal.
Time-Delay Relay
A relay for automatically locking or unlocking a locking unit after a short, fixed time interval.
Time Schedules:
Allows for Access based on time of day, date and user. Also allows for holidays, etc.
Tolerance
Normally stated as a percentage, the maximum allowable deviation of electrical, environmental, or dimensional parameters
Transaction:
A record created that contains pertinent information about an occurrence in the access control and monitoring system..
Transformer
An electric device that changes voltage in direct proportion to currents and in inverse proportion to the ratio of the number of turns of its primary and secondary windings. The input side of a transformer is called the primary side; the output or low-voltage side is called the transformer secondary.
Transient
Any increase or decrease in the excursion of voltage, current, power, heat, and so forth, above or below a nominal value that is not normal to the source. (See transient voltage.)
Transient Suppressor:
A device that protects data lines from high transient such as lighting and inductive loads. They are recommended where there are data communications lines between the reader and its electronics which are subject to high-transient situations. Two are required: one at each end of the exposed communications lines.
Transient Voltage
Refers to several parameters of a transient: (1) the peak or maximum voltage reached, (2) the rate of rise of the transient (dv/dt), and (3) the duration of the transient. Transient voltages are generated when inductive load, such as solenoids, contactors, motors, relays, and so forth, are de-energized. Although some devices have excellent protection against tecse sometimes damaging excursions, when a transient is known to b- present, it should be suppressed at the source. Diodes and metal oxide varistors (MOVS) are commonly used as suppressors.
Trickle Charge
A low-powered electrical energy source provided to keep standby batteries fully charged.
Twisted Pair
A cable composed of two small insulated conductors, twisted together without a common overing. The two conductors of a twisted pair are usually substantially insulated, so the combination is a special case of a cord.
U
Underwriters Laboratories (U.L.)
an independent product safety testing and certification organization.
V
Volt (V)
A unit of electromotive force. It is the difference of potential required to make a current of one ampere flow through a resistance of one ohm.
Voltage
The term most often used (in place of electromotive force, potential, potential difference, or voltage drop) to designate electrical pressure that exists between two points and is capable of producing a flow of current when a closed circuit is connected between the two points.
Voltage Drop
Voltage loss experienced by electrical circuits due to two principal factors: (1) wire size and (2) length of wire runs.
Volt/Amp (VA) Rating
The product of rated input voltage multiplied by the rated current. This establishes the “apparent energy” available to accomplish work.
W
Watt
The common unit of electrical power. One watt is dissipated by a resistance of one ohm through which one ampere flows.
Wiegand Card Key:
A plastic card, approximately the shape of a credit card, which has an embedded module of inert, specially treated ferromagnetic wires which generate a voltage pulse that can be sensed by a coil within the card reader.
#
24-hour circuit
A circuit that is continuously active regardless of whether the alarm system is armed or disarmed.
24-Hour Clock
Time keeping convention, commonly known as military time, wherein the day runs from midnight to midnight and is divided into 24 hours. The hours run from 0 to 23 with 24 designating the day’s end at midnight. For example, 00:10 = 10 minutes after midnight, 08:20 = 8:20 am, and 20:15 = 8:15 pm.
24-Hour Zone
A zone that is continuously active regardless of whether the alarm system is armed or disarmed.
2-Wire Smoke Detector
A class of smoke detectors that employs the same two conductors to supply power and to signal detector activation.
4-Wire Smoke Detector
A class of smoke detectors that employs two conductors to supply power and two to signal detector activation.
A
A
ampere (amp).
AC
alternating current. Also, armored cable.
AC line carrier
Refers to a technology that employs existing 120 VAC wiring to carry signals from a transmitter to a receiver for purposes of controlling devices or appliances, also referred to as power line carrier (PLC). AC voltage A voltage that is constantly changing in both amplitude and polarity. It is generally described by it's amplitude and frequency (cycles per second expressed in Hertz). Example: 120 VAC, 60 Hz
Access code
(1) A group of numbers (usually 4 - 6 digits) that is used to arm/disarm and control various functions of a security alarm system.
(2) Personal Identification Number (PIN). A group of numbers and/or letters that allow entry to a restricted area or system.
Access control
The act or process of limiting ingress to, egress from, or both, by persons or vehicles, any buildings or areas.
Access control card
A card that can be coded with data which is required by a card reader to gain access to an access controlled area.
Access privileges
The specific access rights conveyed to an individual by access code, personal identification code or other means.
Account
A file or record of client information main tained by an alarm or monitoring company.
Account code
The number assigned to a file or record of client.
Acoustic
Pertains to sound, hearing, audio frequencies.
Acoustic sensor
A device that is designed to detect and respond to sound. It may be a simple microphone or a sophisticated detector employing filters, discriminators and signal processing circuitry which responds only to a particular sound or sound patterns.
Active card
An access card that emits a signal after being excited or interrogated by the card reader.
Active sensor
A device that generates and transmits a signal into the area to be protected. It then monitors the returned signal for certain changes which are processed and tested to determine if a triggering threshold has been met. Examples of active sensors include ultrasonic, microwave and photoelectric detectors.
Activity report
A record or file maintained by a monitoring facility of all events communicated by a customers alarm system.
ADA
Abbreviation for the Americans with Di sabilities Act. See Americans with Disabilities Act.
Addressable device
A module, sensor or other component of an alarm system that can be uniquely identified by the system for the purpose of supervision and/or control.
AFC
Abbreviation for the automatic frequency control. See Automatic frequency control.
AGC
Abbreviation for the automatic gain control. See Automatic gain control.
AH
Abbreviation for the ampere hour (AH or Ah). See Ampere hour.
AHJ
Abbreviation for the authority having jurisdiction. See Authority having jurisdiction.
Alarm
(1) A system or device to used to detect and indicate specific events or conditions.
(2) A condition, status or mode of a system employed to monitor prescribed conditions that indicates a state of aler
Alarm Abort
A false alarm reduction feature supported by some control panels which cancels transmission of an alarm to the monitoring facility if the system is disarmed by entering a valid User Code at the system keypad before the expiration of the Communications Delay Time. Transmission of an Alarm Abort Code is usually a programming option.
Alarm condition
A state of alert status indicated by a device or system employed to monitor prescribed conditions when those conditions have occurred.
Alarm control
(1) A device that controls, monitors and processes signals from sensing devices and initiates prescribed outputs according to those signals.
(2) A computer processor that controls an alarm system.
Alarm discrimination
The ability of some devices to differentiate between the burglar and fire outputs of a control panel.
Alarm dispatch
An alarm condition that results in off-site notification and the summoning of police, fire, etc.
Alarm indicating device
Any device which generates an audible, visual or electrical signal upon an alarm condition such as sirens, bells, strobes, digital communicators, etc.
Alarm initiating device
Any device which when activated will generate, or cause to be generated, an alarm condition.
Alarm Memory
A feature provided by most control panels that provides an indication if an alarm has occurred during the last armed period.
Alarm receiver
A device used by a monitoring facility that receives and decodes the signals sent by a control panel’s digital communicator.
Alarm Reporting Codes
Signals transmitted by the alarm system’s digital communicator to a monitoring facility’s receiver that identify specific events occurring on the system.
Alarm response time
The time period between when an alarm system goes into an alarm condition and when responders such as police and fire department arrive on the scene.
Alarm screen
A window screen which has a fine wire conductor interwoven with the screen fabric such that if the screen is cut the conductor will be cut as well creating a fault on the zone to which the screen is connected.
Alarm system
A device or an assembly of devices for the purpose of indicating a prescribed condition such as unauthorized entry; fire, over temperature, water flow, etc.
Alarm verification
A false alarm reduction feature supported by some control panel that resets a fire/smoke detector for a brief period and reports only if the detector trips a second time or if another detector on the fire loop trips.
Alkaline cell
A primary cell which uses potassium hydroxide as an electrolyte rather than ammonium chloride as found in the carbon-zinc cells. Alkaline cells offer longer shelf and better performance than their predecessors.
Alligator clip
A spring loaded clip with two long, serrated jaws made of a conducting material that is used to make temporary connections.
Alphanumeric
A character set containing letters and numbers.
Alphanumeric keypad
(1) A small keyboard device used for entering alphanumeric data into an alarm system for the purpose of controlling and/or programming.
(2) An alarm system keypad which displays system information alphanumeric information on a Liquid Crystal Display or indicator lights.
Alternating current
(AC) A current that is constantly changing in amplitude and direction. It flows in a circuit in one direction while it rises from zero to a maximum value then decreases to zero and reverses direction, it rises from zero to a maximum value in the new direction then decreases to zero thus completing one cycle.
Alternating current voltage
(AC, ACV) A voltage that is constantly changing in amplitude and direction. It increases in amplitude in one direction while it rises from zero to a maximum value then decreases to zero and reverses direction, it rises from zero to a maximum value in the new direction then decreases to zero thus completing one cycle.
Ambush code
A code entered into the keypad by the user of an alarm system indicating a duress condition that initiates a silent alarm.
American National Standards Institute
(ANSI) A United States organization of companies, governmental agencies, trade associations and consumer groups that develops and promulgates standards and operates a voluntary certification program.
American Standard Code for Information Exchange
(ASCII) A code that employs 7 or 8 bits (1 byte) to represent 256 alphanumeric characters and control codes used to standardize communications for data devices.
American Wire Gauge
(AWG) is the American standard for measuring the diameter of non-ferrous conductors. Gauge numbers range from 0000 to 40, the smaller the gauge number the larger the diameter of the conductor. In general, the larger the diameter the greater the Ampacity (current carrying capacity) and the lower the resistance of a given conductor.
Americans with Disabilities Act
(ADA), federal law requiring that "reasonable accommodation" be made in public places for those with disabilities.
Ammeter
Instrument used to measure the flow of an electrical current in a circuit.
Amp
Abbreviation for ampere.
Ampacity
Current carrying capacity expressed in amperes.
Ampere
A unit of measurement of electrical current. A rate of electron flow of 1 coulomb per second (6.3 x 10 18 electrons) past a given point on a conductor equals 1 ampere.
Ampere hour
Ampere hour (amp hour, AH, Ah) is one ampere of electrical current flowing for a period of one hour. It is expressed as the product of the value of current flow times the period of flow. Example: 1 amp flowing for 5 hours = 5 AH 1 amp flowing for .5 hours = .5 AH or 500 milliamp hours .5 amp (500ma) for 24 hours = 12 AH Term is generally used in the alarm industry to express the storage capacity of standby batteries and how that capacity relates to the length of time the battery could power the alarm system in the event of power failure.
Amplifier
A device used to increase the amplitude or strength of a signal.
Analog
Refers to continuous change in a property.
Analog meter
An electro-mechanical measuring device which uses a moving pointer on a graduated scale.
Analog sensor
A device that is capable of producing an output that is continuously variable over a given range. Examples of analog sensors include temperature sensors, rate-of-flow sensors, pressure sensors, etc.
Analog signal
A signal that is continuously variable. Opposite of analog is digital.
Analog to digital converter
A circuit or device that samples an analog signal and converts it to a collection of bits (binary coded decimal) that accurately represents the signal.
Annunciation
The process or act of indicating an alarm condition or change of status of an alarm system, usually by visual or audible means.
Annunciator
Circuitry or a device either integrated or a separate module that alerts to a condition or change of status of an alarm system, usually by visual or audible means.
ANSI
Acronym for American National Standards Institute.
Antenna
A conductor connected or coupled to a receiver or transmitter for the purpose of receiving or transmitting electro-magnetic radiation.
Anti-jam
(1) A feature supported by some control panels that helps prevent phone line tie-up by incoming calls from interfering without going calls made by an alarm system.
(2) Anti-jam detection is a feature of most control panels supporting wireless receivers that provides for detection and annunciation of radio frequency signals that interfere with the operation of the wireless receiver.
Anti-Takeover
A feature supported by most control panels which utilizes Access Codes or programming methods that makes difficult or prevents assuming control of an alarm system that was installed by another party.
Applied voltage
The electromotive force (EMF) impressed upon a circuit as an input.
Arc
A discharge or flow of an electrical current through or across a material which is normally classified as an electrical insulator.
Area detection
Protective coverage of a space, volume or item.
Area Partitioning
Subdividing a protected area into sections or areas that can be controlled independently by a single control panel and one or more keypads.
Area sensor
A detector that has it's zone of detection primarily focused on a given area, such as an entry way, wall, gun cabinet, etc.
Arm
(1) The act of placing an alarm system in an armed mode of operation.
(2) To turn on and alarm system.
Armed
A mode of operation of an alarm system that allows any enabled sensor to cause an alarm condition upon activation.
Armed Light
A visual indication, usually an LED, that an alarm system is in an armed state.
Armed report
A signal transmitted to a monitoring facility indicating that an alarm system has been armed.
Armored cable
A cable which employs an outer flexible metal shield, tube or braid to protect the internal conductors.
ASCII
Acronym for American Standard Code for Information Exchange.
Attack
The attempt or the act of gaining access to an area or system.
Attenuation
The reduction of the amplitude of a signal. It is the opposite of gain.
Audible alarm device
A sounding device such as a siren, bell or klaxon used as a local indication of an alarm condition. Also a piezoelectric buzzer, chime or other sounding device used to annunciate a change in status of an alarm system.
Audible Exit Beep
A false alarm reduction feature supported by most control panels that annunciates an Exit Delay in progress by a beeping sound which, on most systems, changes in pitch or rhythm for the last ten or fifteen seconds of the delay period to suggest urgency.
Audio
General term describing sound detected by the human ear. Changes in air pressure detected by the eardrum are perceived as sound. Audio frequencies are generally considered to be those in the region of 20 Hz to 20 kHz.
Audio discriminator
A circuit used to process and test audio signals for the purpose of qualifying and acting upon certain types of sounds while ignoring others.
Audio frequency
Generally considered to be those frequencies in the region of 20 Hz to 20 kHz. This is considered the normal hearing range for a young adult.
Audio listen-in
A feature supported by some control panels which, when enabled and connected to suitable audio pickup devices, allows remote monitoring of sounds from a protected area.
Audio monitor
A network of audio pickups (microphones) connected to amplifiers which enables monitoring an area for sounds.
Authority having jurisdiction
Any federal, state or local decision making agency, office, appointee or individual having lawful authority to interpret and en force laws, codes, rules, etc. Examples: Building inspector, Electrical Inspector, Plumbing Inspector, Fire Marshall, Insurance Company Representative, Owner, Owners Representative, etc.
Automatic Arming
A feature supported by Some control panels which provides for automatic arming of an alarm system at a specified time on specified days of the week.
Automatic frequency control
A circuit which automatically maintains the frequency of another circuit by detecting and compensating for frequency changes (drift).
Automatic gain control
A circuit which automatically controls the gain or amplification of another circuit thereby maintaining a constant output for varying input signal levels.
Automatic iris
An optical device that adjusts automatically to varying light levels.
Automatic reset
A feature supported by some alarm systems that, after an alarm, returns the system to its pre-alarm state upon the expiration of a per-programmed period of time.
Automatic shutoff
A feature supported by some control panels, which silences the annunciator after a pre-programmed period of time. Also referred to as bell cut-off.
Auxiliary Power Connections
Terminals provided on many alarm system control panels for the purpose of supplying power to ancillary devices.
Away
An alarm system armed condition or mode that activates both interior and perimeter zones.
Away Arming
A feature supported by most alarm systems that activates both interior and perimeter zones.
AWG
Abbreviation for American Wire Gauge.
B
B Connector
A small, insulated, crimp on style wire splice, sometimes containing a moisture/corrosion resistant silicone gel filling, commonly used in security alarm system wiring. Also referred to as beanies and chicklets.
BA
Abbreviation for burglar alarm.
Backlighting
Lighting used on some alarm system keypads to make an LCD display and or keys easier to read.
Backup battery
A battery used as a temporary power source in the event of interruption of primary power, usually located in the metal enclosure that houses the control panel. Also referred to as standby battery.
Balun
An impedance-matching device used to convert an unbalanced line to balanced or balanced line to unbalanced.
Battery
(1) A DC voltage source that consists of two or more cells.
(2) A device used for storing electrical energy.
Battery back-up
(Standby battery) A battery used as a temporary power source in the event of interruption of primary power, usually located in the metal enclosure that houses the control panel.
Battery Calculation
|A calculation which takes alarm system current requirements and battery capacity into account to determine the length of tie the system can function in the event of a primary power failure.
Battery Charger
(1) A DC power source used to charge a storage battery.
(2) The circuitry on a control panel that charges the alarm system's standby battery.
Beanies
See B Connector
Bell
An electro-mechanical sounding device that utilizes an electromagnet to cause an arm (clanger) to strike a gong.
Bell cut-off
(Bell time-out) A feature supported by some alarm systems that will silence a siren or sounding device after a prescribed period of time.
Bell Squawk
A brief sounding of a bell or siren.
Binary
(Binary code) A base two numbering system with only two values, zero (0) and one
(1), widely used in digital processing.
Biometric
Refers to authentication/verification via analysis of a physical characteristic (i.e.biological data). Typical physical characteristics used in biometrics are fingerprints, retina, iris, hand geometry and voice patterns.
Building code
Regulations established and enforced by a lawful authority describing minimum standards for construction of buildings.
Building permit
Approval granted by a local agency that permits the construction or renovation of a building.
Burglar Alarm
A network of sensors and annunciating devices connected to a control panel in such fashion as to form a system capable of de tecting a break-in, intrusion or burglary.
Buried Probe
A sensor designed to be buried in the earth, normally used to detect pedestrian of vehicular presence or passing. Examples include ported coaxial cable, seismic detectors, magnetic field detectors, etc.
Bus
An electrical conductor or set of conductors that serve as a common connection for electrical circuits.
Butt Set
A modified telephone handset used to monitor and test telephone lines and equipment, also referred to as Lineman’s Test Set.
C
Cable
Two or more conductors, which may be insulated or un-insulated bound together, they may be covered or encased by a metallic shielding and/or an outer insulating jacket.
Cable tie
A fastener used for binding individual conductors or cables together.
Call-Back
A communications protocol for control panel downloading procedure wherein the control panel answers a downloading computers telephone call, both the control panel and the computer hang up and the control then calls a number which has been designated as that of the downloading computer. This procedure provides a high level of security by insuring that only the designated downloading number has access to system programming.
Can
The metal enclosure that houses an alarm system's control panel.
Capacitive reactance
(Symbol XC) Measured in ohms, the opposition offered by a capacitor to the flow of an alternating current. XC varies inversely with capacitance and frequency.
Capacitor
A device consisting of two conductive surfaces separated by an insulating material which stores electrical energy in an electrostatic field, blocks the flow of direct current and the flow of alternating current in a circuit.
Cell
The smallest unit of a battery, individual cells are interconnected to form a battery.
Central station
An alarm monitoring facility which receives and acts upon signals transmitted to them by subscribers alarm systems.
Charging
The process of storing electrical energy in a storage battery whereby it's chemicals are returned to their original state by the application of an appropriate electrical current.
Charging current
The electrical current flowing into a battery or component being charged.
Chicklets
See B Connector
Chime
An audible signal with a rhythmic tone used to annunciate a change in status of an alarm system, such as the opening of a door.
Circuit
A path for the flow of an electrical current. The path must be complete (closed circuit) before current flow can take place.
Circuit breaker
A resetable current limiting device used to protect electrical circuits and equipment from excessive current flow.
Class II transformer
A transformer that is inherently current limited.
Closing report
A signal sent to a central station by an alarm system indicating that the system has been armed.
Coaxial Cable
A cable consisting of an insulated center conductor surrounded by an outer flexible braid or solid tubing which constitutes a second conductor running equidistance and parallel to the first.
Code
(1) A set of rules and regulations promulgated by a governing body specifying minimum standards pertaining to a given subject, such as building code, electrical code, etc.
(2) A group of numbers and/or letters that allow entry to a restricted area or system, such as access code.
Color code
A system using colors to identify various para meters of electrical conductors, circuits and components. Examples:
(1) Battery leads use red and black to indicate the positive and negative leads (respectively).
(2) Conductor pairs in communications cables are indicated using different colors.
(3) Values of resistors and capacitors are marked on the body of the device with colored rings or dots.
Communications Cancel
An optional alarm communications Reporting Code supported by some control panels that may be transmitted when an alarm is aborted by entering a valid access code after the alarm signal has been sent but before the expiration of the Alarm Cancel (Alarm Abort) Window.
Communications Delay
The period of time between the beginning of an alarm condition and the transmission of remote notification signals to a monitoring facility.
Communicator Format
The established communications protocol, designated by control panel programming, that will be used for communications between the alarm system’s digital communicator and the receiver at a monitoring facility.
Compatibility listed
A listing method that identifies certain devices as being compatible with various makes and models of control panels.
Conductor
(1) Any material capable of supporting the flow of an electric current.
(2) A wire that carries an electric current.
Contact
A switching device that is activated manually, by a magnet, by a relay or other means, that acts as a sensor.
Contact ID
A relatively fast DTMF communications format developed by Ademo used by alarm system digital communicators for information exchange with a remote monitoring facility.
Continuous Rating
Refers to the maximum load that a power supply can support indefinitely without excessive temperature rise, voltage drop, ripple voltage, etc and/or interruption of output by activation of an overcurrent protection device.
Control panel
A device that controls, monitors and processes signals from sensing devices and initiates prescribed outputs according to those signals.
CS
Abbreviation for Central Station.
Current
(1) The flow of electrons in a conductor.
(2) The flow of an electric charge.
D
Data Bus
Conductors or cable that is employed to transfer data and control signals.
Day zone
A zone that is active when the alarm system is armed or disarmed but has different annunciation and reporting characteristics for each mode.
DC
Abbreviation for direct current.
DC voltage
A voltage that does not change in polarity.
Dealer
A company that sells, leases and installs alarm systems.
Decimal Data
Data or information using the base ten numbering system employing the digits 0 through 9.
Default
(1) Preset values, or original settings and adjustments on a device or system as preassigned by the manufacturer.
(2) The act of returning an alarm system's programming to preset values.
Default programming
An alarm system's basic programming as preassigned by the manufacturer.
Delay Zone
A zone, normally used for entry/exit doors, which when faulted starts a timer and will initiate an alarm on an armed system only upon expiration of the programmed delay period.
DEOL
Abbreviation for Double End of Line.
Detection
The act or process of sensing an event.
Detector
A device capable of sensing an event and generating an output based on its occurrence.
Device
An apparatus, contrivance or instrument suitable for a particular purpose.
Digital communicator
Circuitry integrated on the control panel or a stand-alone device that electronically dials a telephone number and transmits distinctive digital codes that carry information regarding the status of the alarm system to an alarm monitoring facility.
Digital meter
A measuring instrument that samples and displays values on a digital readout, typically capable of measuring voltage, current and resistance.
Diode
(1) A non-linear electrical device or component which supports current flow in a single direction only. Also referred to as a rectifier.
(2) A semiconductor device having two terminals which exhibits a high resistance to electrical current flow in one direction and a low resistance in the opposite direction which results in current flowing through the device in one direction only.
Direct current
A flow of electrons through a conductor in one direction only.
Disarm
The act of changing the mode or status of an alarm system from that which allows any enabled sensor to cause an alarm condition upon activation to the systems ready state.
Disarmed
The mode, condition or state of an alarm system that is not armed, sometimes referred to as the alarm being off.
Discharge
To draw, drain or otherwise remove electrical from a battery, capacitor or other electrical or electronic device or component.
Distributor
As pertains to the alarm industry, a company or individual that sell alarm equipment to alarm dealers.
DIY Alarm Forum
An online security alarm forum where professionals from all segments of the industry volunteer their time and expertise to help other professionals, do-it-yourselfers, homeowners and end-users who have questions or problems regarding alarm systems. Beyond just wanting to help, our objectives are to further consumer education with respect to operation of security and alarm systems, to assist homeowners and do-it-yourselfers with technical support in an effort to raise the overall quality of their projects and to provide for the exchange of ideas amongst the professionals. We hope that our efforts will be a positive reflection on the alarm industry in general and that the information we provide will result in a better appreciation in the importance of proper design, installation and operation of alarm systems.
Door Chime
(1) An annunciator that provides an audible signal upon the opening or opening and closing of a door.
(2) A feature supported by most alarm system control panels which provides an audible signal with a rhythmic tone to annunciate a change in status of a protection circuit, such as the opening or opening and closing of a door.
Doppler Shift
The apparent change in frequency of a signal caused by relative motion between the signal transmitter and receiver, the familiar example being the change in pitch of a train whistle as the train approaches and then passes the location of the observer.
Double End of Line
Referring to the employment of two separate components for End of Line supervision for the purpose of reducing ambiguity with respect to undefined states or conditions on the line.
Downloading
Transferring data from a computer or other programming device to an alarm system via direct connection, telephone or Ethernet connection.
Downloading Access Code
A code that identifies a computer or other programming device to an alarm system’s control panel, permitting access for the purpose for the purpose of uploading and/or downloading data.
Downloading software
Software that facilitates transferring data from a computer or other programming device to an alarm system via direct connection, telephone or Ethernet connection.
DTMF
Abbreviation for Dual Tone Multi-Frequency.
Dual Technology Sensors
Sensors that utilize two separate technologies for the purpose of enhancing detection and/or reducing false alarms.
Dual Tone Multi-Frequency
(DTMF) Two simultaneous audio frequencies used to control telephone switching equipment, such as dialing, and other control circuitry.
Duress Code
(1) A code, password or pass phrase used by an individual when that person is being forced to gain access to a protected area or system.
(2) An special Access Code, which initiates a silent alarm, used when a person is being forced to disarm an alarm system.
DVM
Abbreviation for digital voltmeter.
DVOM
Abbreviation for digital Volt-Ohm-Meter.
Dynamic battery test
A test that checks battery voltage after the battery placed under predetermined load conditions for a given length of time.
E
E
(1) The symbol for voltage.
(2) The symbol for emitter.
EEPROM
Acronym for Electrically Erasable Programmable Read-Only memory.
Electric current
(1) The flow of electrons in a conductor.
(2) The flow of an electric charge.
Electrical circuit
(1) A path for current flow.
(2) The interconnection of electrical conductors, components and/or devices.
Electrical metallic tubing
Ridged metal tubing used to protect electrical wiring, also known as thin-wall conduit.
Electricity
A form of energy produced by the flow or accumulation of charged particles of matter.
Electromagnetic
(1) Referring to the relationship between the electric and magnetic fields caused by the flow of charged particles through conductors.
(2) Referring to magnets produced by the flow of an electric current through a conductor.
Electromagnetic spectrum
The entire range of electromagnetic radiation beginning with the lowest frequency, longest wavelength and moving in a continuous progression thru the highest
frequency shortest wavelength
Electromotive force
(EMF) The pressure or force (voltage) that causes the flow of charged particles.
Electron
A negatively charged particle that orbits the nucleus of an atom. The flow of electrons constitutes and electric current.
Electrostatic
Positive or negative electrical charges at rest.
EMF
Abbreviation for Electromotive Force.
EMT
Abbreviation for Electrical Metallic Tubing.
End of line relay
A device used to supervise or monitor power supplied to powered sensors on an Normally Open loop or zone, such as 4-wire smoke detectors.
End of line resistor
A termination resistor placed at the end of a supervised zone or loop.
End of line supervision
A method of monitoring the integrity of a zone or loop that usually employs a termination resistor of a specified value.
Entrance delay
The time period between the actuation a sensor on a zone defined as a delay zone and the initiation of an alarm, also referred to as Entry Delay.
EOL
Abbreviation for End of Line denoting the end of an electrical line or circuit.
Event code
A reporting code transmitted by an alarm system's digital communicator that identifies a specific event or occurrence, such as burglary, fire, etc.
Event log
A file containing a limited history of certain actions or mode changes that have occurred on an alarm system.
Exit alarm
An alarm initiated upon exiting a protected area.
Exit delay
The time allotted after arming an alarm system for leaving a protected area without initiating an alarm.
Exit Delay Restart
A False alarm reduction feature supported by some alarm system control panels that provides for a one-time restart of the Exit Delay timer if a violation occurs on a Delay Zone within the original Exit Delay time period. For example: A system having an Exit Delay of 60 seconds is armed, a Delay Zone door is opened and closed as the premises is exited, opening the door again within the original 60 second delay period will restart the delay. A second reentry will not restart the delay for a second time.
Exit Time Restart
See Exit Delay Restart
F
FA
Abbreviation for Fire Alarm.
Factory default programming
An alarm system's basic programming as preassigned by the manufacturer.
Fail Safe
A type of lock that automatically unlocks in the event of electrical power loss.
Fail Secure
A type of lock that automatically locks in the event of electrical power loss.
Failure to Communicate
(FTC) A condition that results when an alarm system’s digital communicator is unable to complete successful communications with a monitoring facility receiver.
False alarm
An alarm, not including properly performed system tests, that is initiated without the presence or existence of an actual alarm condition.
False alarm dispatch
(1) An alarm that results in the summoning of emergency responders when no emergency exists.
(2) A false alarm that results in the summoning of emergency responders.
Fault
An abnormal condition on a circuit or line.
F-Connector
A crimp-on, twist-on or compression connector used to terminate coaxial cable, commonly used on cables for TVs, VCRs and CCTV equipment.
Federal Communications Commission
A government agency responsible for the regulation and supervision of all electronic and electromagnetic communications, transmissions and emissions in the United States.
Fire alarm system
A system and all associated devices, either stand-alone or integrated with another system or systems, that monitors for, detects and annunciates the presence of fire.
Fire detector
Commonly a smoke detector or heat sensor.
Fire Loop
A protective circuit or zone which supports fire detection or fire alarm initiation devices, such as smoke detectors, pull stations, etc.
Fish
(1) To push an object such as a stiff steel wire or a metal, plastic or fiberglass rod through a wall cavity, conduit or hole for the purpose of pulling a wire or cable back through the wall cavity, conduit or hole.
(2) The stiff steel wire or a metal, plastic or fiberglass rod used to fish.
(3) The wire(s) or cable that is being fished.
Fish tape
A stiff but flexible tape used to fish wires or cables.
Fixed English Keypad
An alarm system keypad which displays system information via preprogrammed English language words, messages and/or icons.
Flash memory
A non-volatile memory chip that can be erased and rewritten with appropriate software.
Flush mounted
A mounting or installation method that recesses a device or component into the surrounding material resulting in an even or flush surface.
Flying leads
Refers to a conductor or group of conductors which are terminated in a connector at one end leaving the opposite ends free.
Foil
A thin metallic strips or tape that is cemented to a glass surface for the purpose of forming an electrical circuit that will open if the glass is broken thereby triggering an alarm system.
Force arm
A feature supported by some control panels that automatically bypasses any open or faulted zones which enables arming of the alarm system.
Form A contact
A single-pole, single-throw, normally open contact.
Form B contact
A single-pole, single-throw, normally closed contact.
Form C contact
A single-pole, double-throw, contact.
Fuse
A non-resetable overcurrent protection device which employs a metal link that melts at a given current level thereby opening the circuit.
G
Gang box
A steel or plastic box used to mount electrical outlets, switches, etc. and making electrical connections.
Gas Detector
A sensor designed to detect the presence or quantity of a specified gas.
Gel Cell Battery
A lead-acid battery that employs a gelled electrolyte to prevent spillage, commonly used as a standby power source for alarm systems.
Glassbreak vibration detector
A sensor that is attached to glass windows and doors that detects cutting or breakage.
Grommet
A ring or eyelet that is inserted into a hole in a chassis or box to prevent chaffing of wires and cables that pass through the hole.
Ground
(1) An electrical connection to a large common conducting body.
(2) An electrode buried or driven into the earth.
(3) A short (unintentional grounding) in an electrical circuit.
Ground Fault Circuit Interrupter
A power receptacle with a safety device that automatically disconnects power to the circuit if leakage current to ground exceeding a safe value is detected.
Grounding system
(1) A circuit consisting of an electrical ground and a conductor or a network of conductors extending therefrom to various devices, appliances or equipment.
(2) A unified electrical connection to earth ground where utility grounds are connected to a common grounding point resulting in a common electrical potential and reducing hazards from electrical shock, equipment damage and electrical interference.
H
Handshake
The initial communications between an alarm system's digital communicator and a monitoring facility's receiver that determines the parameters of the communications format and establishes synchronization.
Hardware Default
A procedure normally requiring a physical act or temporary change to the control panel to affect a default to basic factory programming values, such as depressing a push button, changing the position of a switch or installing a jumper wire.
Hardwire
Physically connecting an alarm systems control, modules and components with conductors and cables.
Heat detector
See heat sensor.
Heat sensor
A device that detects and responds to a given temperature or to a prescribed rate of temperature increase.
Hertz
(Hz) A unit of measurement for frequency equaling one cycle per second (cps). Example 60 Hz. = 60 cycles per second
Hexadecimal
A numbering system which uses a base of 16, where numbers 0 through 9 and letters A through F represent the 16 digits.
Hexadecimal Data
Data or information using a base 16 numbering system, where numbers 0 through 9 and letters A through F represent the 16 digits.
High frequency
Those frequencies occupying that part of the electromagnetic spectrum between 3 and 30 Megahertz (MHz). Note: 1 MHz = 1,000,000 Hz = 1,000,000 cps
Holdup alarm
An alarm or zone type which when activated causes a silent alarm, the signal or reporting code transmitted to the monitoring facility by the alarm system's digital communicator indicates a crime in progress.
Holdup button
A device used to initiate a holdup alarm condition.
Homerun
A wiring method that routes conductors or cables from individual sensors to the control panel rather than connecting multiple sensors on a single cable run.
Hybrid
See Hybrid Alarm System.
Hybrid Alarm System
An alarm system, which combines the characteristics and functionality of both Hardwired and Wireless system alarm systems.
I
Inductor
(1) A conductor or coil, with a core of air or other material, formed by a conductor used to add inductance to an electrical circuit.
(2) An electronic component exhibiting the properties of inductance: Energy stored in a magnetic field surrounding the device, opposition to changes in current flow and an opposition to the flow of alternating current that increases with frequency.
Infrared
(Symbol IR) Light that is invisible to the human eye, with wavelengths between 760 nanometers and 1000 microns, it occupies that portion of the electromagnetic
spectrum just below visible red.
Infrared beam
A projection or column of light in the infrared portion of the electromagnet spectrum.
Infrared motion detector
A sensor which detects changes in the infrared radiation pattern of a protected area. Signal changes are then processed and compared to known criteria representing the type of motion the sensor was designed to detect.
Infrared sensor
A device used to detect the presence of or changes in infrared radiation or signals. Examples: infrared motion detector, some types of smoke detectors, photoelectric detectors, etc.
Input
Energy, data or condition applied or delivered to a circuit or device to achieve a certain result.
Input voltage
Voltage applied or delivered to a circuit or device to achieve a certain result.
Installer Programming
A level of programming accessed with an Installers Code which is used to program all control panel options.
Installers Lockout
An anti-takeover feature supported by most alarm system control panels which provides the option of restricting access to defaulting procedures.
Instant Zone
A protective circuit, loop or zone which when faulted will initiate an immediate alarm condition on an armed system.
Insulation
A non-conducting material that is used to coat, cover or encapsulate a conductor to prevent current loss.
Insulator
A material or device that resists the flow of an electric current, used to separate conductors from one another, protect circuitry and protect personnel from accidental contact with conductors and circuitry.
Interior Stay/Away Zone
A type of protective circuit, loop or zone which is active when an alarm system is armed in an Away mode but inactive when armed in a Stay mode.
Interior zone
A circuit that connects a sensor or sensors to an alarm system for the purpose of monitoring the interior of a building.
Ion
An atom or group of atoms that have gained an electrical charge through the gain or loss of an electron.
Ionization
A process through which an atom gains an electrical charge by loosing or gaining an electron.
Ionization smoke detector
A type of smoke detector that utilizes changes in the conductivity of ionized air within a detection chamber to detect the presence of smoke.
IR
Abbreviation for Infrared.
Item protection
A class of protection used for high value items such as safes, jewelry, art work, business documents, etc. Also referred to as spot detection and point protection.
J
Jack
A female electrical connector that serves as a receptacle for male electrical connector called a plug.
Jamming
The intentional interference with the reception electrical or electromagnetic signals.
Jump out
Removing an electrical device from a circuit, usually temporarily, using a jumper wire or shunt.
Jumper
An electrical connection placed between two or more points in an circuit or circuits.
Junction box
An enclosure where electrical connections and splices are made.
K
k
Abbreviation for kilo, prefix signifying 1000.
Keybus
Conductors or cable that is employed to transfer data and control signals between a control panel and other modules such as keypads, zone expanders, wireless receivers, etc.
Keypad
An alarm system input/output terminal device consisting of a small keyboard, a piezoelectric buzzer and a Liquid Crystal Display and/or indicator lights, used for entering alphanumeric data into the system for purposes of controlling and/or programming and to display system status information. Also see Alphanumeric keypad, LCD Keypad and LED Keypad.
Keypad Lockout
A feature supported by some control panels which provides the ability to lockout or render a keypad inoperative for a programmed time period if a prescribed number of invalid access codes are entered.
Keypad Zone
A feature supported by some control panels which provides for adding a zone to the system by connections made to zone terminals made available on certain keypads.
Keyswitch
Electrical switch requiring a key to operate.
Keyswitch Zone
A feature supported by some control panels which, when enabled in programming and used in conjunction with a keyswitch, allows arming and disarming of the system by the keyswitch.
KHz
Abbreviation for Kilohertz, 1 kHz = 1000 Hertz (Hz) = 1000 cycles per second (cps).
Kilo
Prefix signifying 1000. Kilohertz = 1000 Hertz. 1 Kilohertz (1 kHz) = 1000 cycles per second (cps).
Kiss-Off
An electrical signal indicating that a data transmission between two systems or devices is complete. Example: The receiver at a monitoring facility sends a Kiss-off signal to an alarm systems digital communicator signifying completion of communications.
Klaxon
(Trademark) An electromechanical horn used as a signaling device.
L
LCD Keypad
An alarm system keypad that provides system information on a Liquid Crystal Display (LCD).
LED
Abbreviation for Light Emitting Diode.
LED Keypad
An alarm system keypad that provides system information through the multi-function Light Emitting Diodes (LED).
Light Emitting Diode
A semiconductor device that emits light when it’s p-n junction is biased in the forward direction.
Lightning
An electrostatic discharge that occurs between positive and negative charges associated with thunderstorms. Discharge may be cloud to ground, ground to cloud or cloud to cloud. Current flows during the discharge have been calculated to be in excess of 100,000 amperes.
Line carrier
Also referred to as power line carrier (PLC) and AC line carrier, a technology that utilizes the AC power line to conduct signals from a transmitter to a receiver for the purpose of controlling another circuit, device or appliance.
Line seizure
A capability of some data communications devices, such as an alarm system's digital communicator, to take and maintain control of a phone line for the duration of it communications requirements.
Line voltage
The voltage of the main power supply and the branch circuits powering the wall receptacles or the voltage supplied by the power company.
Lineman’s Test Set
A modified telephone handset used to monitor and test telephone lines and equipment, also referred to as a Butt Set.
Load
(1) A device or multiple devices drawing electrical current and consuming power.
(2) The current being drawn by a device or multiple devices.
Local alarm
An alarm system that provides audible and/ or visual notification of an alarm condition in, on premises only and does not communicate a remote an off-site notification. Local alarm system Alarm annunciation or notification, usually audible and/or visual,in or on the premises.
Loop
A detection circuit consisting of either Normally closed sensors that are connected in series or Normally Open sensors connected in parallel.
Loop resistance
The resistance of the conductors, sensor contacts and End of Line Termination resistor, if any, as measured across the two loop conductors at the control panel location with the loop disconnected from the panel.
Loop response
The length of time that a zone must remain violated (either open or closed depending upon the loop type) to insure that the control panel circuitry will recognize the event.
M
M
Abbreviation for the prefix Mega, denotes million or a multiplier of one million, as in
MHz
(Megahertz), MV (Megavolt), etc.
mA
Abbreviation for milliamp, also represented as ma. 1 mA = 1/1000 of an ampere.
Magnet
A device, object or material that produces a magnetic field and attracts iron and steel.
Magnetic contact
An electrical switching device designed to be actuated by a magnetic field, also referred to as magnetic switch.
Magnetic reed switch
An electrical switch enclosed in a hermetically sealed tube designed to be actuated by a magnetic field.
Magnetic sensor
A sensor designed to detect changes in magnetic fields, commonly used as a driveway sensor to detect vehicular traffic.
Magnetic switch
An electrical switching device designed to be actuated by a magnetic field, also referred to as magnetic contact.
Main
Referring to electrical power as delivered by electrical utility provider.
Master user code
That access code which provides unrestricted access to all end-user functions on an alarm system.
Mega
Prefix denoting million or a multiplier of one million, as in megahertz, megawatt, etc.
Mercury Switch
An electrical switch, consisting of electrical contacts and a small puddle of mercury encapsulated in a glass bulb, which is actuated when the bulb is positioned such that the mercury flows to the contact(s) and completes the circuit.
MHz
Abbreviation for one million (M) hertz (Hz).
Microwave
A term applied to electromagnetic radiation (radio waves) occupying that portion of electromagnetic spectrum between 1 Gigahertz (1 GHz) and 30 Gigahertz (30 GHz) and characterized by propagation in straight lines.
N
Neutron
One of three basic particles of an atom, the neutron carries no electrical charge.
Non-Alarm Zone
Protective circuits, loops or zones which are active at all times and may be annunciated visually, audibly or by other means when faulted but do not cause an alarm.
Non-Power Limited
Refers to circuits and/or devices which are not Power Limited as defined by National Electrical Code 2005 Article 725.41 and Tables 11A and 11B. See Power Limited.
Normally closed
Electrical contacts in a switch, relay or other device that are closed when not actuated by an external force (at rest).
Normally Closed Loops
(1) A protective circuit which in its normal, secure state forms a complete, continuous circuit and is an open circuit when activated.
(2) A term used by some manufacturers of alarm system to designate a protective circuit that does not employ End of Line terminating resistors.
Normally open
Electrical contacts in a switch, relay or other device that are open when not actuated by an external force (at rest).
Notification appliance
A device that provides an audible and/or visual indication of an alarm condition.
Nucleus
The positively charged core of an atom consisting of protons and neutrons.
Nuisance alarm
A false alarm, an alarm caused by a condition or event other than those the system was designed to detect.
O
Object protection
A class of protection used for high value items such as safes, jewelry, art work, business documents, etc. Also referred to as spot detection and item protection.
Ohm
Unit of measurement for resistance and impedance, defined as that amount of resistance in an electrical circuit that will allow a current flow of one ampere with an applied voltage of one volt. See Ohm's Law.
Ohmmeter
A device used to measure electrical resistance.
Ohm's Law
Expresses the relationship between voltage (E), current (I) and resistance (R) in an electrical circuit. It states that the current in amperes is equal to the applied voltage (electromotive force) in volts divided by the resistance in ohms. This is normally expressed by the algebrai c equation E = IR, where E is equal to the product of I (current in amperes) times R (resistance in ohms).
In it's three basic forms:
E = IR
I = E/R
R = E/I
Open circuit
An electrical circuit that is not a complete path for the flow or electrons and therefore current flow is not possible.
Open circuit system
(Open Loop) A protective circuit in which Normally Open sensors are connected in parallel and no current flows until a sensor is activated.
Opening report
A signal sent to a central station by an alarm system indicating that the system has been disarmed.
Overcurrent device
A device used to protect electrical circuitry from excessive current flow such as a fuse, circuit breaker, or PTC circuitry.
P
P
Abbreviation for Power.
Panel
The circuitry, usually on a printed circuit board, that provides the primary processing and control functions for an alarm system. Also referred to as Control and Control Panel.
Panel Identification Code
A code programmed into a control panel which provides a means of identifying the panel to downloading computers.
Panic alarm
An alarm generated by a 24 hour protective circuit that indicates an emergency condition.
Parallel
A method of connecting circuits or devices whereby each element is connected across every other element, the source voltage is applied to each branch of the circuit and there are multiple paths for current flow.
Partition
A section or subdivision of a protected area which can be controlled and operate independently fro other sections.
Passive detector
A sensor which detects changes in the environment of a protected area without emitting any type of signal.
Passive infrared motion detector
A sensor that detects the movement of infrared energy radiated by the human body as it moves across a relatively constant background level of radiation.
Passive infrared sensor
(PIR) Any sensor that utilizes infrared radiation in a measurement or detection process, the term is commonly used to denote a passive infrared motion detector.
Passive sensor
A detector which senses changes in the environment of a protected area without emitting any type of signal.
Password
A word, phrase or a code used by a person to identify themselves, also see access code, PIN.
Perimeter
Referring to boundaries, the outer boundaries of a building, area or object.
Perimeter detection
Detection of access or entry occurring at the outer boundaries of a building or area.
Permit
An official document from an lawful authority having jurisdiction which conveys permission for a certain act or task.
Personal identification number
(PIN) A number or code assigned to an individual which serves to identify and/or provide access to restricted areas or systems.
PGM
Abbreviation for Programmable or Programmable Output.
Photoelectric detector
A device that converts electromagnetic radiation in the infrared, visible and ultraviolet portions of the spectrum into electrical energy that is used to control indicators or other devices.
Photoelectric sensor
A device that converts electromagnetic radiation in the infrared, visible and ultraviolet portions of the spectrum into electrical energy.
Pico
A prefix signifying one millionth of one millionth, 1 micro micro, 10 -12 or 0.000000000001
Pigtail
An electrical splice made by placing two or more conductors side-by-side in a tight bundle with their stripped, bared ends parallel and in-line, then twisting the bared ends together.
PIN
Acronym for Personal Identification Number.
PIR
Acronym for Passive Infrared, term is commonly used to refer a Passive Infrared Sensor and a Passive Infrared Motion Detector.
Plenum
A chamber or container used for air-handling which specifically includes the space between a drop-ceiling and the structure above, such chambers, containers and areas require special wiring techniques and materials.
Plenum rated
A rating (approval) applied to conductors, cables and materials suitable for use in plenum areas.
Plunger Switch
An electrical switch which utilizes the movement of a spring loaded shaft or plunger to make or break an electrical connection. Commonly employed in recessed applications to protect doors and windows or as a Tamper Switch on Panel Enclosures, box covers, cabinet drawers, etc.
Point protection
A class of protection used for high value items such as safes, jewelry, art work, business documents, etc. Also referred to as spot detection and item protection.
Positive
(1) As refers to a positive electrical charge, a state or condition resulting from a deficiency of electrons.
(2) The terminal or connection on a direct current power supply to which electrons will flow when connected to a complete electrical circuit, usually designated by "+", "Pos" or the color red.
Positive electrical charge
A state or condition resulting from a deficiency of electrons, the opposite of a negative electrical charge.
Positive temperature coefficient
A term used to describe a direct relationship with temperature.
Power
(P) The rate of doing work, measured in Watts.
Power consumption
Electrical energy used by a circuit or device, measured in Watts.
Power factor
As applies to alternating current, the ratio of True Power (W) to Apparent Power (VA), expressed as a decimal, that reflects the phase relationship between the voltage and current in the circuit caused by reactive loads.
Power Limited
Refers to circuits and/or devices which are restricted with respect to voltage levels and/or current delivering capacities as defined by National Electrical Code 2005.
Power loss
Power that is dissipated by conductors and components that does not contribute to useful work, sometimes referred to as copper loss or I 2 R loss.
Power supply
A generator, battery, electrical circuit or other device used as a source of electrical power.
Pre-alarm
A false alarm reduction feature supported by most alarm system control panels which provides audible notification that the Entry Delay timer has been activated and that an alarm will be initiated if the system is not disarmed before the expiration of the delay period.
Pre-Alert
See Pre-alarm.
Pressure mat
A type of sensor, a rubber mat that responds to pressure created when the weight is applied, such as a person stepping on the mat.
Program
(1) A sequence of instructions that define the operation of an alarm system under a specific set of conditions.
(2) The act of placing coded instructions into an alarm systems memory that will define the operation of the system.
Programmable output
Outputs, generally relay or open collector, supported by some control panels that are used to power or control ancillary devices upon alarm or other conditions as defined by system programming.
Programmable Read-Only Memory
A memory chip that becomes a read-only memory after programming.
Programming Worksheets
A complete listing of options and settings that may be programmed into an alarm system control panel, usually showing factory default settings, providing spaces for the installer to write in programming values prior to actual programming.
PROM
Acronym for Programmable Read-Only Memory.
Protected area
(1) An area monitored by an alarm system.
(2) A controlled or restricted access area.
Protective circuit
A zone, loop or other circuit connecting a sensor or sensors to an alarm system.
PTC
(1) Abbreviation for Positive temperature coefficient.
(2) A solid state, self-restoring current limiting device or component, usually a thermistor, which increases in resistance with an increase in temperature thereby automatically reducing current flow.
Q
Quick Arm
A feature supported by some control panels which, if enabled, provides “short-cut” key presses for arming.
Quick Exit
A feature supported by some control panels which, if enabled, provides means for a single, short (several minutes) exit/reentry through a Delay Zone without requiring disarming an armed system.
R
R1
Designation used to identify the Ring conductor of a telephone pair when used as an output from a circuit or device.
Radio frequency
Any frequency in the electromagnetic spectrum that is suitable for transferring electronic signals or propagation.
Radio frequency interference
Radio frequency signals, either naturally occurring or generated by man, that cause interference with equipment, device or object.
RAM
Acronym for Random-Access Memory.
Rate of rise
A type of heat detector that senses a specified temperature increase within a given length of time and initiates an output if those conditions are met.
Reactance
(Symbols X L, X C) Measured in Ohms, the resistance offered to alternating current by circuit containing inductive reactance, capacitive reactance or any combination of the two. A load that includes inductive and/or capacitive reactance and results in a phase difference between the applied alternating current voltage and the current flow in the circuit.
Read-Only Memory
A memory circuit or memory device in which information has been stored (hard-coded or hard-wired) in such fashion that it can be read but not written to or changed except under certain conditions and will be retained when power is removed from the circuit or device. Ready Light An alarm system keypad light which, when illuminated, indicates that all zones are secure and/or the system is ready to arm.
Rectifier
A device, electrical circuit or component the converts alternating current into direct current.
Reed switch
A switch consisting of electrical contacts mounted on ferrous metal actuating arms in a hermetically sealed glass tube. The switch, which is actuated by a magnetic field, is commonly used as a sensor on alarm systems.
Regulated power supply
A power supply whose output is automatically maintained within a given range over a prescribed variation in load conditions.
Relay
An Electromechanical switching device that is actuated by an electric current flowing in it's solenoid. Frequently used in a low current circuit to control a high current circuit or to provide electrical isolation between different electrical circuits.
Remote alarm
An alarm system that transmits alarm signals off-site to a remote monitoring facility in conjunction with or without local annunciation of the alarm event.
REN
Acronym for Ringer Equivalency Number.
Resistance
(R,Ω) Measured in Ohms, the opposition to the flow of an electric current.
Resistive load
A load comprised of pure resistance, lacking reactive load components.
Resistor
Electrical component or device which opposes the flow of electrons, used in electrical circuitry to control current flow.
Restoral Reporting Codes
Signals sent to a monitoring facility by an alarm system indicating that a previously reported alarm or trouble condition has been cleared.
RF
Abbreviation for Radio frequency.
RFI
Abbreviation for Radio frequency Interference.
Ring
Telephony term describing one of the two conductors that constitute the primary pair or talk circuit providing landline telephone service. The Ring conductor, usually either Red or Blue/White, is negative with respect to the Tip conductor and the voltage across the pair is approximately 48 VDC. The term has nothing to do with the "ringing" of the phone but rather is a throwback to the days of operators making manual phone connections using 1/4 inch phone plugs which had Tip, Ring and Ground connections.
Ringer Equivalence Number
A number relating to the load presented by a telecommunications device to a telephone line.
Ring-Hang-Ring
A communications protocol whereby a telecommunications device will answer an incoming telephone call only if a call is made to the number, allowed to ring once or twice, hung up and then called a second time within a prescribed time period.
Rings Until
A communications protocol whereby a telecommunications device will answer an
incoming telephone call only after a designated number of rings.
Ripple
An alternating current voltage component that is superimposed on a direct current voltage.
RJ
Refers to Registered Jack, telecommunications and data jacks that are registered with the Federal Communications Commission.
RJ31X
A Registered Jack, the usage of which is mandated by the FCC, that provides a quick- disconnect means for automated dialing and signaling equipment while allowing other telephone equipment on the circuit to continue to function normally. When connected in series with the telephone line and as the first device on the premises line after the Telephone Company service point (Dmarc), it will provide line seizure for the alarm system.
ROM
Acronym for Read-Only Memory.
RS-232
A standard interface for serial communications commonly utilizing a 9 pin (DB-9) or 25 pin (DB-25) connector.
RS-485
A two-wire serial data transmission standard employed by some alarm system control panels for keybus or data bus communications.
S
Sealed lead acid battery
A maintenance free battery that employs a gelled electrolyte, requires no water replacement and can be operated in any position.
Security Industry Association
An association of manufacturers and other companies serving or related to the security industry which promotes the growth and betterment of the industry.
Semiconductor
(1) A material that shares some of the characteristics of both conductors and insulators in that it s neither a good conductor nor a good insulator.
(2) A generic reference to solid state devices such as diodes, transistors and integrated circuits.
Sensor
A device capable of detecting an event and generating an output based on its occurrence.
Sensor Reset
To return or restore a sensor to a normal or ready state.
Series circuit
A circuit in which there is only one path for current flow, a given value of current enters the circuit from a power source, flows in turn through each device in the circuit, and then flows back to the power source.
Service loop
Extra wire left in a loop at the ends of wire runs to facilitate future maintenance or modifications.
Shock Sensor
A sensor which detects vibration or movement resulting from an intrusion or attempted intrusion.
Short
A low resistance connection, either intentional or accidental, between two points in an electrical circuit that effectively bypasses part of the circuit.
Short circuit
A low resistance connection, either intentional or accidental, between two points in an electrical circuit that effectively bypasses part of the circuit.
Shunt
(1) A parallel connection.
(2) A bypass of a part of a circuit by a jumper or short.
SIA
Acronym for Security Industry Association.
SIA CP-01
Standards promulgated by the Security Industry Association which provide guidelines for manufacturers and installers of alarm systems aimed at reducing false alarms.
Single-pole double throw
A three terminal switching device which allows one of its terminals (frequently the center terminal or the terminal designated as Common) to be connected to either of the other two terminals, depending on the switch position, but not both at the same time.
Single-pole single throw
A two terminal switching device which allows its terminals to be either connected or not connected depending on the switch position.
Siren
An audio output device used on an alarm system that consists of a speaker and integrated circuitry that generates high pitched steady tones, warbling tones or a combination thereof. Also referred to as a sounder, local annunciation device, notification appliance, etc.
Smoke detector
A sensor that monitors a given area for visible or invisible products of combustion and upon detection generates an audible warning and/or provides an output to an alarm system.
Snake
Any device used to pull conductors, cables or other items through inaccessible areas such as wall cavities, tubing, conduits, pipes, etc.
Software Default
A procedure normally requiring a programming change to the control panel to affect a default to basic factory programming values.
Solid Conductor
A bare or insulated single strand of drawn material used to transmit a signal or carry an electrical current.
SPDT
Abbreviation for Single-Pole Double Throw.
Speaker
An electromechanical device that converts electrical signals into sound waves.
Splice
(1) An electrical connection formed by joining two or more conductors.
(2) The act of joining or connecting together two or more conductors.
Spot detection
A class of protection used for high value items such as safes, jewelry, art work, business documents, etc. Also referred to as spot protection, point protection and item protection.
Spot protection
A class of protection used for high value items such as safes, jewelry, art work, business documents, etc. Also referred to as spot detection, point protection and item protection.
SPST
Abbreviation for Single-Pole Single Throw.
Standby power
A power source which provides power upon the loss of primary power, such as the standby battery for an alarm system.
Static
An electrical charge that results when an excess or deficiency of electrons occurs on the surface of an object.
Static discharge
The rapid depletion, equalization or neutralization of a static charge which occurs when electrons flow to or from a charged body either through a conductor or through or across a material normally classified as an electrical insulator.
Stay
Referring to an armed mode supported by most control panels which is characterized by an automatic bypassing of certain Interior Sensors when a system is armed and an Entry/Exit Delay Zone is not violated before the expiration of the Exit Delay timer.
Stay Arming
Arming an alarm system by any means that results in the such that certain Interior Sensors are not active. See Stay.
Strip
To remove the insulation from the end of an insulated conductor, usually for the purpose of making a splice or connection.
Stud finder
Any device used to locate studs behind a finished wall, such as those using a magnet to locate nails driven into the studs and those employing ultrasonic technology to detect a change in density.
Supervise
Monitoring preformed by the control panel for the presence, condition or status of wiring, sensors or devices connected to the alarm system.
Supervised line
Zones, loops or other wiring connected to an alarm system whose integrity is monitored by the control panel as a precaution against tampering and accidental damage.
Supervisory circuit
Circuitry in an alarm system that provides line supervision.
Surface mounted
Describes a mounting or installation method that results in a device or component being mounted on the surface of the item being protected or on a surface in the area being protected.
Surge
A rapid change in voltage or current beyond normal values.
Surge protection
A device, circuitry or component that protects equipment from damage caused by an electrical surge.
Surge suppressor
An electrical device used to protect other electrical equipment and appliances from damage caused by short duration, high voltage surges (transients) on power,telephone, cable TV, Ethernet lines, etc. as may be caused by faulty equipment or lightning.
Swinger
An intermittent opening and closing on a circuit generally caused by faulty wiring, a defective sensor or environmental conditions resulting in false indications on an alarm system.
Swinger Shutdown
A feature supported by most alarm system control panels which automatically bypasses protective circuits after they have initiated an alarm in order to prevent repeated alarm reports caused by a malfunctioning circuit.
T
T1
Designation used to identify the Tip conductor of a telephone pair when used as an output from a circuit or device.
Tamper device
A device or circuitry used to detect an attempt to gain access to or modify circuitry or components of an alarm system.
Tamper switch
A switch used to detect an attempt to gain access to or modify circuitry or components of an alarm system.
Telco
Refers to the telephone company.
Telephone line monitor
A device used to monitor and indicate the operational status of a telephone line.
Telephone Line Monitoring
The act of monitoring a telephone line to verify line integrity and/or functionality.
Terminal
A screw, clip or other fastener used an electrical connection point.
Terminal strip
A row or line of screws, clips or other fasteners used an electrical connection points.
Terminating device
A component or device connected to the end of an electrical line to establish know values on that line.
Test
To exercise or operate a system or a device for the purpose of establishing its functionality.
Test Transmission
A signal transmitted by an alarm system’s digital communicator to a monitoring facility for the purpose of verifying the operation of the communicator and the telephone line or other transmission media.
Tip
Telephony term describing one of the two conductors that constitute the primary pair or talk circuit providing landline telephone service. The Tip conductor, usually either Green orWhite/Blue, is positive with respect to the Ring conductor and the voltage across the pair is approximately 48 VDC.
TLM
Abbreviation for Telephone Line Monitor or Telephone Line Monitoring.
Toggle
To alternate or switch between states, such as on/off.
Toggle Options
Control panel Programming Options which are enabled or disabled by the repeatedly depressing the same key, button or control.
Tone generator
Circuitry or a device that generates a signal in the audio frequency range.
Toner
A device consisting of a tone generator which is connected to an electrical conductor and a receiving probe which is used to trace, follow and identify that conductor.
Transformer
An electrical device that is used to increase or decrease an Alternating Current Voltage and/or provide isolation between electrical circuits.
Transient
A short duration spike or surge in current or voltage occurring in an electrical circuit.
Transistor
A semiconductor device that controls the flow of an electric current used in switching and amplification applications in electrical circuitry.
Trap detection
A class of protection utilizing sensors in high traffic areas or areas likely to be used by an intruder.
U
Ultrasonic motion detector
An active sensor that transmits ultrasonic signals in a protected area then monitors for changes in those signals as an indication of motion.
Ultraviolet
(Symbol UV) Light that is invisible to the human eye, with wavelengths between 5 and 400 nanometers, it occupies that portion of the electromagnetic spectrum just above visible violet.
Underwriters Laboratory
An independent testing laboratory that tests electrical materials, methods and products and establishes standards relating to safety.
User Functions
Alarm system control panel options and functions which can be programmed or set using a Master User Code or User Code, such as setting the date and time, adding Users, enable/disable Auto-Arm features, performing system tests, etc.
User Programming
Alarm system control panel programming that is accessible by a Master User Code. See User Functions.
UV
Abbreviation for Ultraviolet
V
V
Abbreviation for Volt.
VA
Abbreviation for Volt Ampere (Volt Amp).
VAC
Abbreviation for Volt(s) Alternating Current.
Valence electrons
Electrons in the outermost shell or orbit of an atom that may be gained or lost due to chemical action or electrical charge.
Very High Frequency
That portion of the electromagnetic spectrum between 30 and 300 MHz.
Very Low Frequency
That portion of the electromagnetic spectrum between 10 and 30 kHz
VHF
Abbreviation for Very High Frequency.
Vibration sensor
A passive detector that employs electrical contacts which are opened and closed by vibrations of a protected area or object.
Visible light
That portion of the electromagnetic spectrum that produces light or causes reflections that are visible to the human eye, generally considered to be those wavelengths between 400 and 700 nanometers.
VLF
Abbreviation for Very Low Frequency.
Voice Dialer
A telephone dialing device capable of verbal reporting by delivering prerecorded announcements.
Voice Over IP
(VOIP) is a technology that allows for telephone calls to be made over computer networks by converting analog voice signals into digital data.
VOIP
Abbreviation for Voice Over Internet Protocol.
Volt
A unit of measurement of electrical potential or pressure. See Voltage.
Voltage
Electrical pressure or potential that causes current flow, also referred to as Electromotive force (EMF).
Volt-Ohmmeter
A test instrument used to measure voltage, resistance and current, also referred to as a multimeter.
Volumetric detection
A class of detection with a specific protected area, such as a given area within a building, a room, a confined area within a room, etc.
VOM
Abbreviation for Volt-Ohmmeter
W
Walk test
(1) A procedure performed to verify the functionality of alarm system whereby, after placing the system in test mode, the operation of sensors, detectors, annunciators and communications devices is verified.
(2) The process of checking the operation and adjustment of a motion detector.
Walk through
An inspection procedure performed on a building or area to determine what security measures and alarm system requirements are necessary to meet the level of protection desired by the owner or occupant.
Water sensor
A device that detects the presence or quantity of water at a given location.
Waterflow sensor
A device placed in water pipe that detects the movement or flow of water within the pipe.
Watt
(1) (Abbreviation W, Symbol P) Unit of measurement for electrical power.
(2) The rate of doing work.
More:
In DC circuits calculated by the basic formula: P = IE, where P = power in Watts, I = current flow in Amperes and E = Electromotive force in Volts. In AC circuits the Power Factor (PF), which reflects the phase difference caused by the reactive component of the load, must be taken into consideration and the formula becomes P = I*E*PF.
Wet cell
A type of electrochemical cell that uses a liquid as an electrolyte.
Wide gap contact
A type of magnetic contact that is able to operate with a greater separation between the contact switch and the energizing magnet than standard magnetic contacts.
Window foil
A thin metallic strips or tape that is cemented to a glass surface for the purpose of forming an electrical circuit that will open if the glass is broken thereby triggering an alarm system.
Wire
A length of bare or insulated, solid or stranded, drawn metal.
Wire nut
A fastener that is screwed on or over wires used to join two or more wires together.
Wired alarm system
An alarm system that uses wire and cable to physically connect modules and sensors to the control panel.
Wireless
(1) Employing electromagnetic radiation rather than wires or cables.
(2) Radio or radio signals.
Wireless alarm system
An alarm system that employs electromagnetic radiation in the form of radio signals rather than wire and cable to convey information between sensors and the control panel.
Wireless Receiver
A radio receiver which may be either integrated with an alarm system control panel or keypad or an add-on stand-alone module, which provides wireless functionality to the system. See Wireless Alarm System.
Wrong Code Lockout
A feature supported by some control panels which provides the ability to lockout or render a keypad inoperative for a programmed time period if a prescribed number of invalid access codes are entered.
Z
Z
Symbol for Impedance.
Zinc carbon cell
A primary cell, the zinc carbon (carbon zinc) cell, technically a Leclanche cell, is an electro-chemical cell comprised of a zinc container, electrolytic cathode paste mixture and a carbon rod. The zinc container serves as the negative electrode and the carbon rod, in contact with the paste, provides positive electrode contact. Developed in the late 1800's, the zinc carbon cell is still widely used today. Better known as the common dry cell battery, it powers our flashlights and runs our toys.
Zip cord
A two conductor cable with parallel conductors separated by a thin section which will separate easily when the conductors are pulled apart.
Zone
A detection circuit comprised of one or more sensors, it is usually a subdivision of a larger protected area based on location or function. The division of a protected area into zones permits individual zones (areas) to function independently and annunciate separately. Proper zoning (the process of dividing the area into zones) will provide those monitoring the system with information regarding the location and nature of an emergency. It also facilitates service or maintenance of the system by making troubleshooting easier.
Zone Attributes
Programmable options which collectively define the operation of a protective circuit, loop or zone.
Zone Crossing
A feature supported by some alarm system control panels which requires activation or faulting of more than one zone within a prescribed time period before an alarm will be initiated.
Zone expander
Modules or devices added to systems, providing the control panel supports such expansion, to increase the numberof zones available on the system.
#
2 Wire
Transmission medium using the same two wires for transmit and receive channels. Either leased line or dial up.
4 Wire
Transmission system using 2 separate pairs of wires for transmit and channels. Leased line or dial up can be achieved on PSTN by dialing 2 separate numbers.
1/8" (3.5mm)
Mini Plug is an audio / video connector plug for some monitors and recorders. Camcorders are especially likely to use this type of plug for audio / video input and audio / video output. 1/8" mini plugs carry composite signals just like BNC or RCA plugs. However, the mini plug is smaller and can carry both a video and an audio signal over a single connector.
12VDC
Most board cameras, mini cameras and about one third of the professional cameras work with 12VDC, 100mA to 200mA for B/W cameras and 150mA to 300mA for color ones. These cameras usually have DC jacks to accept DC power plugs. You should be careful about the polarity (positive and negative) for this power source. 12VDC power can be supplied by AC Adapter or battery pack. You may even use a "power cord" plugged to the cigarette lighter in a car.
24VAC
About two thirds of the professional cameras work with 24VAC, 20VA to 40VA. The cameras usually have screw type connections and you don't need to worry about the polarity. This power is usually supplied by AC Adapter and you need to prepare separate power cable for the connection. Unlike 12VDC, this power can be transmitted to a long distance up to 450ft and is proper for the cameras that are to be installed outdoor or when you don't have the power outlet near the camera.
A
A/V
Audio / Video
Aberration
A term from optics that refers to anything affecting the fidelity of the image in regards to the original scene.
AC
refers to alternating current electricity. 110 volts AC is the type of electricity most often found in home and office electrical outlets in the United States. Outside the U.S. many countries have standard outlet voltage of 220 ~ 240 volts AC. In addition, many CCTV products use 24 volts AC, for which a separate power transformer is required.
AC Adaptor
Also See: Power Supply - All CCTV devices require power of some sort. Electricity in the United States comes in one form, 110 to 120 AC. The AC adaptor converts the AC power to DC power and will adjust it to a specified amperage. Power supplies should come included with each item.
Access Card
Approximately the size of a credit card, these are specially coded cards given to employees and allow them access to secure locations or devices at work. Access cards utilize several technologies such as magnetic strips, Barium Ferrite, proximity (active or passive), and other methods. They are often ‘swiped’ and read by a device that allows the user or employee access.
Access Code
Similar to a password, this series of numbers or letters enables a user to access a system or computer. At job sites an access code can be the system or process that oversees employees or cars both in and out of certain areas.
Access Point
These are specific entry points in certain secures areas. A card reader and monitor switches allow authorized entry by individuals with access cards.
ActiveX
ActiveX is Microsoft software component technology, mainly used by Microsoft Windows. They facilitate sharing of information between differing applications. Digital video recorders utilize ActiveX to remotely view security cameras online.
Activity Detection
Multiplexers use this feature, which is a video motion detection technique, to give relay closure for alarms and to improve the update times of video cameras.
ADDRESS
A sequence of bits, a character or a group of characters that identifies a network station.
A/D (AD)
Usually refers to analog to digital conversion.
ADC
Analog to digital conversion. This is usually the very first stage of an electronic device that processes signals into digital format. The signal can be video, audio, control output and similar.
AES
Auto electronic shutter - the ability of the camera to compensate for moderate light changes in indoor applications without the use of auto iris lenses.
AGC
Automatic Gain Control. A circuit for automatically controlling amplifier gain in order to maintain a constant output voltage with a varying input voltage within a predetermined range of input-to-output variation.
Alarm Input
A connection from an alarm or sensor that triggers the CCTV unit to start recording if activated.
Alarming
Ability for CCTV equipment to respond to an external input, provide numerous functions such as switch to relevant camera signal and alarm start a VCR.
Algorithms
Its general definition means a set of mathematical instructions to solve a task. In the field of video technology, they enable digital compression of the video picture.
Alphanumeric video generator (also text inserter) - A device for providing additional
information, normally superimposed on the picture being displayed; this can range from one or two characters to full-screen alphanumeric text. Such generators use the incoming video signal sync pulses as a reference point for the text insertion position, which means if the video signal is of poor quality, the text stability will also be of poor quality.
AM
Amplitude Modulation.
Ambient Light Level
This is the amount of background light present at any specific time.
Ampere (amp)
The unit of measure for the rate of electrical current flow characterized by the symbols l(in Ohm's law formulas) and
1. One ampere is the current flowing through one ohm of resistance at one volt potential.
Amplifier
typically refers to a device which adds strength to a signal for a 'better' and / or longer performance ability. Amplifiers can be found for both wired and wireless equipment. A VDA (video distribution amplifier) is designed to extend a video signal through wires by boosting the power of the video signal. Transmitter-end and receiver-end amplifiers can be found for wireless equipment to help increase broadcast range potential.
Amplitude
The maximum value of a varying waveform.
Analog
Two main methods exist for representing data in electronics -- Analog, and Digital. Analog is pertaining to a mechanism that represents data by measurement of a continuous physical variable, as voltage of pressure.
Analog System
Analog cameras are used most often in CCTV applications. Other examples of Analog devices are security VCRs, switchers, multiplexers, and quads. CCTV systems that consist of Analog devices are considered Analog Systems.
Angle of View
Regarding CCTV security cameras, this term refers to the angular range in degrees that you can focus the camera without distorting the image. When focus is distant, the Angle of View is smaller or narrower. When focusing up close, you can generally see a wide Angle of View. The table below gives an approximate value for the angle of the field of view for lenses of various focal lengths. 30° is considered to be a normal view; telephoto (longer) lenses have lower angles. Most CCTV cameras have one of the 3 sizes of imaging devices listed below, 1/4", 1/3" or 1/2". As you can see, this makes a big impact when choosing lenses.
Lens Size
Angle of View
1/4" CCD 1/3" CCD 1/2" CCD
2.8 mm 64° 80° 97°
4.0 mm 45° 60° 74°
6.0 mm 30° 38° 57°
8.0 mm 23° 30° 40°
12.0 mm 15° 20° 30°
16.0 mm 11° 15° 22°
50.0 mm 4° 5° 7°
Annunciator
This is a signaling device, either visual or audio based. For example, wireless annunciators use infrared beams that trigger an audible signal when interrupted, and can be used for security or retail purposes.
ANSI
American National Standards Institute.
Antenna Element
Antennas for wireless equipment are constructed of elements which are specifically tuned to a given frequency or range of frequency to improve gain.
Antenna Gain
refers to any increase or decrease in the strength of a wireless RF radio frequency signal when considering external antenna equipment. Gain is typically measured in terms of decibels (dB) or a number of times of magnification.
Antenna Type
refers to the design of a particular antenna. Common antenna types for wireless CCTV are dipole whip antenna (the most common), yagi, flat panel, omni-directional, parabolic dish, and heliophase..
Anti-aliasing
A procedure employed to eliminate or reduce (by smoothing and filtering) the aliasing effects.
Aperture
The Aperture is the opening of a lens that controls the amount of light let into the camera. The size of the Aperture is controlled by the iris adjustment. By increasing the stop number less light is permitted to pass into the camera. In television optics, it is the effective diameter of the lens that controls the amount of light reaching the photoconductive or photo emitting image pickup sensor.
Aperture Correction
Compensation for the loss in sharpness of detail because of the finite dimensions of the image elements or the dotpitch of the monitor.
Aperture Scale
The aperture scale is referred to as an F-number. Examples are F1, F1.4, F2, F2.8, F4, etc.
Apostilb
A photometric unit for measuring luminance where, instead of candelas, lumens are used to measure the luminous flux of a source.
Archive
Long-term off-line storage. In digital systems, pictures are generally archived onto some form of hard disc, magnetic tape, floppy disk or DAT cartridge.
Armor Dome Camera
Armor Dome refers to a hi-impact reinforced polycarbonate dome casing designed to resist vandalism on this brand of camera.
ARP (Address Resolution Protocol)
ARP is a method determining a host’s Ethernet address from its Internet address. The network receives the ARP request, and then names the IP address. Next, the machine at this address returns its physical address so the information can be sent to it. If supported by all hosts, Internet addresses can be independent of Ethernet addresses.
Artifacts
Undesirable elements or defects in a video picture. These may occur naturally in the video process and must be eliminated in order to achieve a high-quality picture. The most common are cross-color and cross-luminance
ASCII
American Standard Code for Information Interchange. A 128-character set that includes the upper case and lower-case English alphabet, numerals, special symbols and 32 control codes. A 7-bit binary number represents each character. Therefore, one ASCII-encoded character can be stored in one byte of computer memory.
Aspect Ratio
The ratio of width to height for the frame of the televised picture. 4:3 for standard systems, 5:4 for 1K x 1K, and 16:9 for HDTV.
Aspheric
A type of lens in which the spherical surface has been slightly altered to reduce spherical aberration. This type of lens generally allows wide angle viewing with relatively low distortion.
Astigmatism
The uneven foreground and background blur that is in an image.
Asynchronous Data
Most common for of data, where date is passed without any clocks or timing information, uses start and stop bits for synchronization.
AT Commands
A protocol between a modem and terminal equipment for autodialing and configuration of the modem.
ATM
Asynchronous transfer mode. A transporting and switching method in which information does not occur periodically with respect to some reference such as a frame pattern. Attenuator - A circuit that provides reduction of the amplitude of an electrical signal without introducing appreciable phase or frequency distortion.
ATSC
Advanced Television System Committee (think of it as a modern NTSC). An American committee involved in creating the high definition television standards.
Attenuation
In general terms, a reduction in signal strength.
Audio
indicates sound. When audio is listed as a feature of some video product, this usually means one of a few things: a device for monitoring sound (microphone), a wireless transmitter's ability to broadcast sound, or a video recorder's ability to record audio.
Audio Input Plug
refers to the type of connector plug for a device's audio input jack. In most cases, this is a standard RCA connector or 1/8" (3.5mm) mini plug.
Audio Input Type
There are two basic kinds of audio found for video equipment connections: line-level and mic-level. Line-level indicates that the audio input device (like a microphone) must be preamplified in order to record or broadcast the audio signal. All wireless products, recorders, and monitors require line-level microphone connections. For compatibility's sake, all microphones found on this site are line-level and contain preamplifiers.
Auto electronic shutter (
AES) Feature of a camera to adjust for light changes without the use of an auto-iris lens.
Audio Output Plug
refers to the type of connector plug for a device's audio output. In most cases, this is a standard RCA connector or 1/8" (3.5mm) mini plug.
Audio Output Type
Audio output for a device can be either line-level or mic-level (see note above in audio input type). So long as the audio output is line-level, there is no need for mic-level connections. Video recorders and monitors typically have line-level inputs, making connections simple.
Auto Iris (AI)
Cameras with an Auto Iris feature, have the ability to compensate for large variations in light levels. Particularly useful for cameras that need to compensate for changes from bright sunlight to dark shadows. The auto iris circuitry is normally linked to a motorised iris drive that physically opens and shuts the iris on the lens. Closing a physical iris is a much better way to protect a camera from being damaged by bright sunlight then simply using electronics to reduce the signal strength. A diaphragm device in the lens that adjusts to light level changes. The iris diaphragm opens or closes the aperture to control the amount of lights coming through the lens.
Auto-focus Lens
automatically adjusts the lens focus from surrounding scene and keeps a moving object in focus.
Auto Balance
A system for detecting errors in color balance in white and black areas of the picture and automatically adjusting the white and black levels of both the red and blue signals as needed for correction.
Auto Electronic Shutter
A CCTV camera feature that allows the camera to compensate for moderate light changes in indoor applications without the use of Auto Iris Lenses.
Auto Homing
An automatic sequential video switcher which has manual switches or buttons, which allow a single CCTV camera to be displayed on screen without sequential switching.
Auto Iris Control
A lens which allows the Aperture to automatically open or close to maintain proper light levels on the faceplate of the camera pickup device.
Automatic Level Control (ALC)
Allows the auto-iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out detail in shadows.
Auto Light Range
The range of light, e.g., sunlight to moonlight, over which a TV camera is capable of automatically operating at specified output.
Auto White Balance
A feature on color cameras that constantly monitors the light and adjusts its color to maintain white areas.
Automatic Brightness Control
In display devices, the self-acting mechanism which controls brightness of the device as a function of ambient light.
Automatic Frequency
An arrangement whereby the frequency of an oscillator is automatically maintained within specified limits.
Automatic Gain Control
A process by which gain is automatically adjusted as a function of input or other specified parameter.
Automatic Iris Lens
A lens that automatically adjusts the amount of light reaching the imager.
Automatic Light Control
The process by which the illumination incident upon the face of a pickup device is automatically adjusted as a function of scene brightness.
Automatic Terminating (Auto-terminating)
Video signals are normally transmitted along co-axial cable, which require a terminating resistor at either end. If the signal is looped through a piece of equipment that has an input and an output, then it should be terminated if it is the final piece of equipment, but not terminated if it is in between other equipment. Some appliances have a manual switch for this setting, other equipment automatically detects if termination is required and applies the additional resistor as necessary.
AUX
Auxiliary
AVC (Advanced Video Coding)
Both the ITU and MPEG groups have agreed upon AVC as the current video compression standard. ITU calls it H.264, the MPEG group refers to it as MPEG-4, and the public calls it AVC.
AVI
Audio Video Interleave - An audio-video standard designed by Microsoft.
AWG
American Wire Gauge is the measurement of the metal part of the wire diameter. The AWG number is inversely related to size, meaning as the number gets larger the size gets smaller and visa-versa.
B
Back Porch
That portion of the composite picture signal which lies between the trailing edge of the horizontal sync pulse and the trailing edge of the corresponding blanking pulse.
Back Focus
A mechanical adjustment in a camera that moves the imaging device relative to the lens to compensate for different back focal lengths of lenses. This is important when a zoom lens is fitted.
Backlash
Backlash (measured in degrees) is when a camera’s Pan Tilt head cannot stop instantaneously, and is usually caused by excessive looseness in gears, pulleys, or other parts. Pre set PTZ surveillance cameras are rendered ineffectual by Backlash.
Back Light Compensation
is a feature of cameras that automatically adjusts the image to compensate for bright sunlight or bright lights, to give more detail on the darker areas of the image. For example to focus on the detail of a face of a person that has the sunlight shining from behind. BLC indicates the image sensor's ability to automatically adjust in conditions where lighting is from behind the camera to deliver the sharpest and highest quality video image possible.
Balanced Signal
A video signal is converted to a balanced signal to enable it to be transmitted along a twisted pair cable. Used in situations where the cabling distance is too great.
Balun
This stands for Balanced – Unbalanced. Physically, a Balun is a small transformer used to convert audio, video, or VGA signals from balanced to unbalanced, and vice versa. Its practical use is in creating required impedance adjustments for signal transmission between differing wiring systems (like UTP to coaxial cable).
Bandwidth
The number of cycles per second (Hertz) expressing the difference between the lower and upper limiting frequencies of a frequency band; also, the width of a band of frequencies.
Baseband
The frequency band occupied by the aggregate of the signals used to modulate a carrier before they combine with the carrier in the modulation process. In CCTV the majority of signals are in the baseband.
Bar Test Pattern
Special test pattern for adjusting color TV receivers or color encoders. The upper portion consists of vertical bars of saturated colors and white. The power horizontal bars have black and white areas and I and Q signals.
Battery
refers to a stored power device. For mobile and remote applications, one or more batteries can be used.
Battery Run Time
indicates the amount of time a piece of electronic equipment can realistically be powered using a particular battery pack. For instance, the CC-1HAD color board camera has a battery run time of about 24 hours when using eight fresh "AA" alkaline batteries in our BAT-1 or BAT-3 battery packs. More battery time could potentially be obtained with a higher capacity battery. It must also be noted that the more power consumption load on a battery or battery pack.
Baud
A unit of measurement that denotes the number of bits that can be transmitted per second. For example, if a modem is rated at 9600 baud it is capable of transmitting data at a rate of 9600 bits per second. The speed of which data is transmitted, i.e.; 1 baud = 1 Bit per second.
BER
Bit error rate. The ratio of received bits that are in error relative to the total number of bits received, used as a measure of noise induced distortion in a digital bit stream. BER is expressed as a power of 10. For example, a 1 bit error in 1 million bits is a BER of 10–6.
Betamax
Sony’s domestic video recording format, a competitor of VHS.
Bias
Current or voltage applied to a circuit to set a reference operating level for proper circuit performance, such as the high frequency bias current applied to an audio recording head to improve linear performance and reduce distortion.
Binary
A base 2 numbering system using the two digits 0 and 1 (as opposed to ten digits [0-9] in the decimal system). In computer systems, the binary digits are represented by two different voltages or currents, one corresponding to zero and another corresponding to one. All computer programs are executed in binary form.
Biometrics
Biometrics is the technology and science of authenticating individuals by measuring their physiological or behavioral features. In the field of security, they are technologies (‘readers’) used to analyze fingerprints, voice patterns, irises
or retinas, etc.
Bipolar
A signal containing both positive-going and negative-going amplitude. May also contain a zero amplitude state.
B-ISDN
Broadband Integrated Services Digital Network. An improved ISDN, composed of an intelligent combination of more ISDN channels into one that can transmit more data per second.
Bit
A binary digit, the smallest element of information in a binary system.
Bitmap (BMP)
A pixel-by-pixel description of an image. Each pixel is a separate element. Alsoa computer file format.
Bit rate - Bps = Bytes per second, bps = bits per second.
The digital equivalent of bandwidth, bit rate is measured in bits per second. It is used to express the rate at which the compressed bitstream is transmitted. The higher the bit rate, the more information that can be carried.
Blackburst (color-black)
A composite color video signal. The signal has composite sync, reference burst and a black video signal, which is usually at a level of 7.5 IRE (50 mV) above the blanking level.
BLC
Backlight Compensation - The ability of a camera to compensate in cases where a subject with a large amount of background light would otherwise be obscured by blooming or silhouetting.
Black Level
A part of the video signal, close to the sync level, but slightly above it (usually 20 mV - 50 mV) in order to be distinguished from the blanking level. It electronically represents the black part of an image, whereas the white part is equivalent to 0.7 V from the sync level. A measure of picture signal level, that matches to a specified maximum limit for black peaks.
Blanking level
The beginning of the video signal information in the signal’s waveform. It resides at a reference point taken as 0 V, which is 300 mV above the lowest part of the sync pulses. Also known as pedestal, the level of a video signal that separates the range that contains the picture information from the range that contains the synchronizing information.
Blooming
The defocusing of regions of a picture where brightness is excessive.
Black & White (monochrome) Camera
Cameras are available with either color or monochrome image sensors. Monochrome cameras are typically referred to as black and white because video image they produce is in shades of gray. Only black and white CCD cameras have the ability to utilize IR infrared lighting. Also, even without infrared lighting, a monochrome camera will generally perform better in low light conditions than will a color camera equipped with a comparable CCD imager, lens, and quality of manufacture. The black and white cameras deliver amazingly crisp video, and in fact much better than the human eye when only a tiny amount of light is available.
Blanking Period
The period of the composite video signal at black level (0.3V) and below when the retrace occurs.
Blooming
The defocusing of regions of the picture where the brightness is at an excessive level, due to enlargement of spot size and halation of the fluorescent screen of the cathode-ray picture tube. In a camera, sensor element saturation and excess which causes widening of the spatial representation of a spot light source.
BNC connector
These are a type of RF connectors that interconnect two coaxial cables or connect a cable with CCTV components. They’re used in Ethernet networks, video connections, network cards, and cable interconnections.
Bounce
Sudden variations in picture presentation (brightness, size, etc.,) independent of scene illumination.
B-picture
Bi-directionally predictive coded picture; an MPEG term for a picture that is coded using motion compensated prediction from a past and/or future reference picture.
bps (Bits Per Second)
This unit is used to measure the speed data is moved between sources. For example, a 56kbps modem can move 56,000 bits per second.
Braid
A group of textile or metallic filaments interwoven to form a tubular structure that may be applied over one or more wires or flattened to form a strap
Bridging
When a high impedance video line is paralleled to a video source, this is known as bridging.
Brightness
The attribute of visual perception in accordance with which an area appear to emit more of less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.)
Broadband
In television system use, a device having a band pass greater than the band of a single VHF television channel.
Bullet Camera
A type of camera with a bullet like shape. Can be used inside or out. Some come with infrared lighting.
Burned-In-Image
Also called burn. An image which persists in a fixed position in the output signal of a camera tube after the camera has been turned to a different scene or, on a monitor screen.
Bus Network
This is a network type where a transmission medium served as a bus between all attached terminals, and it’s the easiest and cheapest way to connect multiple clients. Computer motherboards and Ethernet networks both employ bus architecture.
Byte
A unit of eight bits is known as a Byte.
C
Cable equalization
The process of altering the frequency response of a video amplifier to compensate for high frequency losses in coaxial cable.
Cable tray
This tray is installed in many sites, and lays cables out lengthwise for economics and organization.
CAD
Computer Aided Design. This usually refers to a design of system that uses computer specialized software.
Cameo
A small part of a monitor’s viewing area (1/16th the screen area) is called a cameo. Multiplexers create multiple analog signals from security cameras and then combine them into multiple cameos on the screen, which enables simultaneous viewing of up to sixteen different camera pictures.
Camera format
Video camera's CCD chips format; 2/3", 1/3", 1/4", etc. Camera Sensor: Video image sensor. CCD or C-MOS chip.
C-/CS-Mount Lenses and Cameras
The security industry has agreed upon a standard size lens mounting thread and coupling diameter with C and CS mount lenses. Cameras built with this type of lens mount can easily be configured with any of a large variety of C and CS mount lenses available for CCTV. Although C and CS are not exactly the same size, most cameras designed for this type of lens can accept either configuration using a simple plastic adapter. These lenses are standardized and will always thread properly, but exchanging C and CS mount lenses does require back focusing. This process requires the user / installer to slowly find the exact right thread position of the lens to ensure a clear video image. An industry standard for lens mounting. C-Mount is 1-inch diameter with 32 threads per inch. A C-Mount lens needs a C-ring when it is mounted on a CS-Mount camera. The C mount lens has a flange back distance of 17.5mm. The CS mount lens has a flange back distance of 12.5mm. C mount lenses therefore have a longer focal distance. CS mount became widely used, because it its more practical for many of today's more compact cameras. Lenses are often supplied with a 5mm spacer ring (sometimes called a C ring) that allows a C mount lens to be used on a CS camera. Most modern cameras are CS.
Candela
A candela is a measurement of luminous intensity and is a replacement to the candle. A unit for measuring luminous intensity. One candela is approximately equal tothe amount of light energy generated by an ordinary candle. Since 1948 a more precise definitionof a candela has become: “the luminous intensity of a black body heated up to a temperature at which platinum converges from a liquid state to a solid.”
CAT5
Category 5 (cable) - type of cable most often used in networking applications.
CATV
Community antenna television.
C-band
A range of microwave frequencies, 3.7~4.2 GHz, commonly used for satellite communications
CCD
stands for charged coupled device. This is a solid-state semiconductor element which uses hundreds of thousands of tiny pixel elements to accept light and translate that information into a vivid, visible picture image. A CCD is one type of camera image sensor. CCDs produce MUCH higher tvres, lower light sensitivity, and better overall video quality than CMOS imagers (also commonly found in CCTV industry cameras). One of the two main types of image sensing device used in cameras. It operates by converting light energy into electrical charge.
CCD aperture
The proportion of the total area of a CCD chip that is photosensitive.
C Mount
A television camera lens mount of the 16 mm format, 1 inch in diameter with 32 threads per inch. C-Mount or Standard Body cameras are designed to accommodate custom lenses. The lenses can be removed and replaced. Standard Body Cameras are the basic model and offer the most diverse range of features.
CCTV
Common abbreviation for Closed-Circuit Television. stands for closed circuit television: a video system which will only be monitored in a closed environment (as opposed to public broadcast). The realm of video security and surveillance is also referred to as CCTV. CCTV Is a Television system that sends a signal to one or more monitors rather than broadcasting over a public network, hence closed-circuit. A standard CCTV system will normally include a CCTV camera (for capturing video), transmitters and receivers (to transfer the video from the source to where it is recorded), a recording system (for video playback), and a monitor (for video monitoring). CCTV systems are primarily used for security purposes inside and outside buildings. However, they can also be used for specialist applications such as mobile police use and interrogation.
CCIR
is the standard monochrome video format used in most of Europe, Israel, and some other places in the world. CCIR products are also generally referred to as PAL because all PAL products can also handle black and white CCIR video. Some camera models available on atss.in are also available in PAL / CCIR video format for foreign clients and special applications.
CCIR 601
An international standard (renamed ITU 601) for component digital television that was derived from the SMPTE RP1 25 and EBU 3246E standards. ITU 601 defines the sampling systems, matrix values and filter characteristics for Y, Cr, Cb and RGB component digital television.It establishes a 4:2:2 sampling scheme at 13.5 MHz for the luminance channel and 6.75MHz forthe chrominance channels with eight-bit digitizing for each channel. These sample frequencies were chosen because they work for both 525-line 60Hz and 625-line 50Hz component video systems. The term 4:2:2 refers to the ratio of the number of luminance channel samples to thenumber of chrominance channel samples; for every four luminance samples, the chrominance channels are each sampled twice. The Dl digital videotape format conforms to ITU 601.
CCIR 656
The international standard (renamed ITU 601) defining the electrical and mechanical interfaces for digital television equipment operating according to the ITU 601 standard. ITU 656 defines both the parallel and serial connector pinouts, as well as the blanking, sync and multiplexing schemes used in both parallel and serial interfaces.
CCTMA
Closed Circuit Television Manufacturers Association.
CCTV
Closed circuit television. Television system intended for only a limited number of viewers, as opposed to broadcast TV.
CCTV camera
A unit containing an imaging device that produces a video signal in the basic bandwidth
CCTV installation
A CCTV system, or an associated group of systems, together with all necessary hardware, auxiliary lighting, etc., located at the protected site.
CCTV system
An arrangement comprising of a camera and lens with all ancillary equipment required for the surveillance of a specific protected area.
CCVE
Stands for closed circuit video equipment. An alternative acronym for CCTV.
CD
Compact disc. A standard of media as proposed by Philips and Sony, where music and data are stored in digital format.
CD-ROM
Compact disk read only memory. The total capacity of a CD-ROM when storing data is 640 MB.
CDS
Correlated double sampling. A technique used in the design of some CCD cameras that reduces the video signal noise generated by the chip.
CFA
Color filter array. A set of optical pixel filters used in single-chip color CCD cameras to produce the color components of a video signal.
Charge-Coupled Device
CCD. For imaging devices, a self-scanning semiconductor array that utilizes MOS technology, surface storage, and information transfer by shift register techniques.
Chip
An integrated circuit in which all the components are micro-fabricated on a tiny piece of silicon or similar material.
Chroma
That quality of color which embraces both hue and saturation. White, black, and grays have no chroma.
Chroma Burst
A reference signal (4.43Mhz) included in the video signal after the horizontal synchronization line pulse.
Chroma Control
A control of color television receiver that regulates the saturation (vividness) of colors in a color picture.
Chroma crawl
An artifact of encoded video, also known as dot crawl or cross-luminance, Occurs in the video picture around the edges of highly saturated colors as a continuous series of crawling dots and is a result of color information being confused as luminance information by the decoder circuits.
Chroma Detector
Detects the absence of chrominance information in a color encoder input. The chroma detector automatically deletes the color burst from the color encoder output when the absence of chrominance is detected.
Chroma gain (chroma, color, saturation)
In video, the gain of an amplifier as it pertains to the intensity of colors in the active picture.
Chromatic Aberration
An optical defect of a lens which causes different colors or wave lengths of light to be focused at different distances from the lens. It is seen as color fringes or halos along edges and around every point in the image.
Chromaticity
The color quality of light which is defined by the wavelength (hue) and saturation. Chromaticity defines all the qualities of color except its brightness.
Chroma key (color key)
A video key effect in which one video signal is inserted in place of areas of a particular color in another video signal.
CIE - Commission Internationale de l’Eclairagé.
This is the International Committee for Light, established in 1965. It defines and recommends light units.
Chrominance
A color term defining the hue and saturation of a color. Does not refer to brightness.
Chrominance Signal
That portion of the NTSC color television signal which contains the color information.
Chrominance-to-luminance intermodulatlon (crosstalk, cross-modulation)
An undesirable change in luminance amplitude caused by superimposition of some chrominance information on the luminance signal. Appears in a TV picture as unwarranted brightness variations caused by changes in color saturation levels.
CIE - Commission Internationale de l’Eclairagé.
This is the International Committee for Light, established in 1965. It defines and recommends light units.
CIF (Common Intermediate Format)
The default frame resolution of 352x288 for DVR systems is known as the CIF.
Cladding
In Fibre Optics the outermost region of an optical cable, lees dense than the centre core, acts as an optical barrier to prevent transmitted light leaking away from the core.
Clamp
A device which functions during the horizontal blanking or synchronizing interval to fix the level of the picture signal at some predetermined reference level at the beginning of each scanning line.
Clamping
The process that established a fixed level for the picture level at the beginning of each scanning line.
Clipping
The shearing off of the peaks of a signal. For a picture signal. This effects the positive (white).
Clock
A name commonly used for any of the sources of timing signals used in synchronous data transmission.
CMOS
Complementary metal-oxide-semiconductor -A major class of integrated circuit technology used for a wide variety of analog circuits such as image sensors, data converters, and highly integrated transceivers for many types of communication.
C-mount
The first standard for CCTV lens screw mounting. It is defined with the thread of 1'' (2.54 mm) in diameter and 32 threads/inch, and the back flange-to-CCD distance of 17.526 mm (0.69''). The C-mount description applies to both lenses and cameras. C-mount lenses can be put on both, C-mount and CS-mount cameras, only in the latter case an adaptor is required.
CMYK
A color encoding system used by printers in which colors are expressed by the “subtractive primaries” (cyan, magenta and yellow) plus black (called K). The black layer is added to give increased contrast and range on printing presses.
Coaxial Cable
A particular type of cable capable of passing a wide range of frequencies with very low signal loss. Such a cable in its simplest form, consists of a hollow metallic shield with a single wire accurately placed along the center of the shield and isolated from the shield.
CODEC
CODEC means compressor/decompressor and is any technology used to compress and decompress data. It converts analogue input into digital, and then converts it back to analogue. CODECS can be either software applications or hardware components, or both. DVRs use CODECS to compress video streams from security cameras, and then store this compressed data on a hard disk.
Color bars
A pattern generated by a video test generator, consisting of eight equal width color bars. Colors are white (75%), black (7.5% setup level), 75% saturated pure colors red, green and blue, and 75% saturated hues of yellow, cyan and magenta (mixtures of two colors in 1:1 ratio without third color).
Color Burst
That portion of the composite color signal, comprising a few cycles of a sine wave of chrominance sub carrier frequency, which is used to establish a reference for demodulating the chrominance signal. Normally approximately 9 cycles of 3.579545 MHz.
Color Camera
Cameras are available with either color or monochrome image sensors. Color cameras produce video images bearing the entire visible spectrum of colors. And because color CCD cameras have come a long way in recent years, the colors of objects appear vivid, crisp, and distinguished on monitoring and playback of video. The color cameras deliver amazingly crisp video, and in many cases better than the human eye when only a small amount of light is available.
Color carrier
The sub-frequency in a color video signal (4.43 MHz for PAL) that is modulated with the color information. The color carrier frequency is chosen so its spectrum interleaves with the luminance spectrum with minimum interference.
Color difference signal
A video color signal created by subtracting luminance and/or color information from one of the primary color signals (red, green or blue). In the Betacam color difference format, for example, the luminance (Y) and color difference components (R–Y and B–Y) are derived as follows:
Y = 0.3 Red + 0.59 Green + 0.11 Blue
R–Y = 0.7 Red – 0.59 Green – 0.11 Blue
B–Y = 0.89 Blue – 0.59 Green – 0.3 Red
The G-V color difference signal is not created because it can be reconstructed from the other three signals. Other color difference conventions include SMPTE, EBU-N1 0 and MII. Color difference signals should not be referred to as component video signals. That term is reserved for the RGB color components. In informal usage, the term “component video” is often used to mean color difference signals.
Color Edging
Extraneous colors appearing at the edges of colored objects, and differing from the true colors in the object.
Color Encoder
A device which produces an NTSC color signal from separate R, G, and B video inputs.
Color field
In the NTSC system, the color sub-carrier is phase-locked to the line sync so that on each consecutive line, subcarrier phase is changed 180º with respect to the sync pulses. In the PAL system, color subcarrier phase moves 90º every frame. In NTSC this creates four different field types, while in PAL there are eight. In order to make clean edits, alignment of color field sequences from different sources is crucial.
Color frame
In color television, four (NTSC) or eight (PAL) properly sequenced color fields compose one color frame.
Color Fringing
Spurious colors introduced into the picture by the change in position of the televised object from field to field.
Color phase
The timing relationship in a video signal that is measured in degrees and keeps the hue of a color signal correct.
Color Purity
The degree to which a color is free of white or any other color. In reference to the operation of a tri-color picture tube it refers to the production of pure red, green or blue illumination of the phosphor dot face plate.
Color Saturation
The degree to which a color is free of white light.
Color subcarrler
The 3.58MHz signal that carries color information. This signal is superimposed on the luminance level. Amplitude of the color subcarrier represents saturation and phase angle represents hue.
Color Sync Signal
A signal used to establish and to maintain the same color relationships that are transmitted.
Color Transmission
The transmission of a signal which represents both the brightness values and the color values in a picture.
Comet Tails
A condition that appears on a VDU that is caused by near burn combined with image movement.
Color temperature
Indicates the hue of the color. It is derived from photography where the spectrum of colors is based upon a comparison of the hues produced when a black body (as in Physics) is heated from red through yellow to blue, which is the hottest. Color temperature measurements are expressed in Kelvin.
Comb filter
An electrical filter circuit that passes a series of frequencies and rejects the frequencies in between, producing a frequency response similar to the teeth of a
comb
Used on encoded video to select the chrominance signal and reject the luminance signal, thereby reducing cross-chrominance artifacts or conversely, to select the luminance signal and reject the chrominance signal, thereby reducing
Composite Sync
A signal containing line and field pulse, but has no video information.
Composite Video Signal
is the standard type of analog video signal utilized by most CCTV video cameras. This signal is plug and play compatible with most consumer television and VCR equipment. However, this type of video should not be confused with digital "component" inputs which may ALSO found on newer televisions and other home video equipment. A composite video signal has the correct phase rate, luminance, and chrominance information to be compatible with a particular video format such as NTSC, PAL, EIA, CCIR, etc. A full video signal that combines picture signal and synchronisation pulses. The combined picture signal, including vertical and horizontal blanking and synchronizing signals.
Compressed Picture
A compressed picture is a full size picture that has been reduced in size while still displaying all of the original screen information.
Compression
The reduction in gain at one level of a picture signal with respect to the gain at another level of the same signal. Compression is the act of taking an incoming signal or image, which can be analog or digital, and restructuring the data such that it takes fewer resources for storage and transmission.
Compression Method
refers to the computer software technique the codec in a DVR video recorder (or DVR card) uses to convert the video signal to digital information so it can be compressed and stored on digital media like a hard disk drive, DVD, or CD. Uncompressed video would require massive processing power and nearly unlimited storage capacity and is, therefore, completely out of the question in the real world. MPEG (M-JPEG) and Wavelet are the most common types of compressed digital video, but there are variants of these in addition to other proprietary formats. MPEG-1 and MPEG-2 typically offer the highest quality recording (DVDs use MPEG-2), but smaller file sizes can be obtained by using a lower tvres, more efficient compression method like Wavelet or MPEG-4. It should also be noted that the method of compression a video codec uses to compress and digitize video information may NOT always indicate the video file type / extension for playback. Instead, the final digital video format available from a DVR recorder on backup (via USB, CD or DVD burner, etc.) could be in AVI format or even a proprietary format despite MPEG compression
Concave
A concave optical lens has an inward curving surface, causing incoming light to diverge.
Concave lens
A lens that has negative focal length, i.e., the focus is virtual and it reduces the objects.
Conditional Refresh
A technique by some video transmission systems, once the first image has been constructed only part of the image that changes is subsequently transmitted, allowing high speed updates when little movement is seen, however the speed of image update decreases.
Conductor
Material with the ability to carry electric current. The term is also used for an electric wire.
Contrast
The range of light to dark values in a picture or the ratio between the maximum and minimum brightness values.
Contrast Control
is a feature of many video monitors. This allows the user to manually adjust the screen contrast for better picture visibility. Contrast Ratio is a monitor specification. This number indicates the dynamic range of brightness (difference between darkest and brightest) a monitor is capable of displaying.
Contrast Range
The ratio between the whitest and blackest portions of television image.
Convergence
The crossover of the three electron beams of a three-gun tri-color picture tube. This normally occurs at the plane of the aperture mask.
Convex
A convex lens curves outwards, and is sometimes known as converging. Light that passes through converges to a focal point.
Convex lens
A convex lens has a positive focal length, i.e., the focus is real. It is usually called magnifying glass, since it magnifies the objects.
Covert
A covert application refers to a situation where you don't want the person to know that they are being watched or recorded. Also known as 'hidden' cameras.
Crosstalk
An undesired signal from a different channel interfering with the desired signal.
Cross Talk
Electrical interference caused by electromagnetic or electrostatic coupling by nearby conductors or external sources. Interference between two or more signals in close proximity within a band pass.
CPU
Central processing unit. A common term used in computers.
CRT (Cathode Ray Tube)
The CRT is a tube found in most televisions, monitors, and video monitors. Once heated, it creates images by emitting a beam of electrons that hit a phosphor-coated surface. The glow of the surface is dependent on the beam’s intensity. Each CRT uses deflection circuitry to control the beam’s movement.
CRO
Cathode ray oscilloscope (see Oscilloscope).
Current Delivery
indicates the amount of electrical current (usually measured in milliamps, amps, or watts) available from some device which has output voltage (like an AC/DC power transformer or a battery pack). Current delivery describes the amount of "juice" a power supply or other product which outputs voltage can deliver to another product in need of electrical power.
Current Draw
indicates the amount of electrical current (measured typically in milliamps or amps) required to safely and effpixelsly power a device.
CS-mount
A new generation of lenses designed for 2/3 inch, 1/2 inch, and 1/3 inch cameras incorporating CS-mounts. The distance from the flange surface to the focal point is 12.5mm. CS-mount lenses cannot be used on c cameras with C mount configuration. These lenses are smaller and less expensive than the C-mount equivalents.
CS-to-C-mount adaptor
An adaptor used to convert a CS-mount camera to C-mount to accomodate a C-mount lens. It looks like a ring 5 mm thick, with a male thread on one side and a female on the other, with 1'' diameter and 32 threads/inch. It usually comes packaged with the newer type (CS-mount) of cameras.
CVBS
Composite video bar signal. In broadcast television this refers to the video signal, including the color information and syncs.
D
D1
D1 is a resolution of 720x486 (NTSC) or 720x576 (PAL), and was one of Sony’s first digitized videotape formats.
Dark Current
The thermally induced current that exist in a photo diode in the absence of incident optical power.
Dark noise
Noise caused by the random (quantum) nature of the dark current.
D/A (also DA)
Opposite to A/D, i.e., digital to analog conversion
DAT
Digital Audio Tape - a technology for sharing massive amounts of digital information in a small package. Used for archiving digital recorded images.
Data Protection
The correlation between the gathering and distribution of data, technology, the public expectation of privacy, and the legal issues involved."
Day / Night Camera
Not to be confused with Infrared Cameras, "Day/Night Cameras" are regular cameras with a highly sensitive CCD chip with the ability to capture quality imagery with very little light present.
dB (Decibel)
Basically, a measure of the power ratio of two signals. In system use, a measure of the voltage ratio of two signals,provided they are measured across a common impedance.
DBS - Direct broadcast satellite.
Broadcasting from a satellite directly to a consumer user, usually using a small aperture antenna.
DC (Direct Current)
DC differs from AC (alternating current) in that electricity always flows thorough it in the same direction. A pair of wires has one positive wire and one negative. Many security cameras are 12 Volt DC, although some can operate at different voltages.
DCT - Discrete cosine transform.
Mathematical algorithm used to generate frequency representations of a block of video pixels. The DCT is an invertible, discrete orthogonal transformation between time and frequency domain. It can be either forward discrete cosine transform (FDCT) or inverse discrete cosine transform (IDCT).
DD (Direct Drive)
This uses a gearless drive mechanism, making it less prone to mechanical failure. PTZ security cameras will often use them for pan, tilt, and zooming.
Decibel
(db) is a logarithmic scale. In the context of CCTV it refers to voltage or signal strength. A 6db increase is equivalent to doubling the signal strength.
Decoder
The circuitry in a color TV receiver which transforms the detected color signals into a form suitable to operate the color tube.
Decompression
Taking digitally compressed DVST information and restoring this to normal video images.
Default Gateway
In order to send data or video between networks, the IP Address of the Router is required. This address is known as the Default Gateway.
Definition
The fidelity of a television system to the original scene.
Degauss
To demagnetize
Delay line
An artificial or real transmission line or equivalent device designed to delay a wave or signal for a specific length of time.
Demodulator
A device that strips the video and audio signals from the carrier frequency.
De-multiplexing
This refers to the procedure of separating different channels of video, audio, or data that were multiplexed at the source.
Depth of Field
The in-focus range of a lens or optical system. It is measured from the distance behind an object to the distance in front of the object when the viewing lens shows the object to be in focus.
Depth of Focus
The range of sensor-to-lens distance for which the image formed by the lens is clearly focused.
DHCP (Dynamic Host Configuration Protocol)
A DHCP refers to the protocol used by a host computer to obtain an IP address so that it can communicate with other host computers. These addresses are usually dynamic, meaning they change periodically, so a connection cannot be obtained (or maintained) over the open Internet. Use of both static IP addresses and dynamic DNS helps establish a consistent connection.
Dielectric
An insulating (nonconductive) material.
Differential gain
A change in sub-carrier amplitude of a video signal caused by a change in luminance level of the signal. The resulting TV picture will show a change in color saturation caused by a simultaneous change in picture brightness.
Differential phase
A change in the sub-carrier phase of a video signal caused by a change in the luminance level of the signal. The hue of colors in a scene change with the brightness of the scene.
Digital disc recorder
A system that allows recording of video images on a digital disc.
Digital signal
An electronic signal where every different value from the real-life excitation (sound, light) has a different value of binary combinations (words) that represent the analog signal.
Digital
Two main methods exist for representing data in electronics, Analog and Digital. Digital information is communicated by designating a circuit on or off.
Digital Signal Processing
An algorithm within the camera that digitizes data (the image). Examples include automatic compensate for backlight interference, color balance variations and corrections related to aging of electrical components or lighting. Functions such as electronic pan and zoom, image annotation, compression of the video for network transmission, feature extraction and motion compensation can be easily and inexpensively added to the camera feature set.
Digital System
Digital CCTV security camera systems are only lately gaining popularity. Most security cameras are still analog, though DVRs are becoming the industry standard. There are some digital cameras available but they are extremely expensive. Most new systems installed today will include analog security cameras and a DVR. Any CCTV security camera system that includes a DVR is considered a Digital System.
Digital Versatile Disk (DVD)
Sometimes called digital video disk. This is an optical disk the same size as a CD, used for storing data of various formats. Including video, audio and computer data.
DIN
Deutsche Industrie-Normen. Germany’s standard.
Disk
A flat circular plate, coated with a magnetic material, on which data may be stored by selective magnetization of portions of the surface. May be a flexible, floppy disc or rigid hard disk. It could also be a plastic compact disc (CD) or digital video disc (DVD).
Distortion
Nonproportional representation of an original.
Direct Drive (DD)
Some auto iris lenses require a DC signal from the camera. These are known as direct drive lenses. Distortion The deviation of the received signal waveform from that of the original transmitted waveform.
Distribution Amplifier
A device that provides several isolated outputs from one looping or bridging input, and has a sufficiently high input impedance and input-to-output isolation to prevent loading of the input source.
Digital Video Recorder (DVR)
This device is capable of accepting one or more video (and sometimes audio) input signals for recording onto digital storage media. A DVR is basically a computer specifically designed to gather and compress video into a digital video format for storage on a hard disk drive or other form of digital media. DVRs are quickly replacing VCR video recorders for security and surveillance purposes without the need for changing tapes. Key differences between DVR and VCR recorders come to available features. Advanced DVRs are capable of accepting multiple video and / audio inputs without the need for bulky and expensive multiplexers or video quads. As well, most DVRs offer built-in motion detection recording (without costly and conspicuous PIR motion sensors), and many can be remotely viewed and played back over the internet. Some models may easily be backed up onto external media for long term archival. These backup methods may include CDs, DVDs, flash media cards, or via USB to a computer or other storage device. Eyespyvideo.com offers several DVR models, all selected for their superior reliability, ease of use, quality of manufacture and variety of useful features. This is a device that records video signal digitally. Normally this is on a large hard drive in the machine. For this reason it is sometimes known as a hard disk recorder (HDR). Digital Video Recorder records video pictures digitally.
DIP
Switches Dual Interface Poll switches usually allow you to change the configuration of a circuit board to suit your application.
DivX
DivXNetworks created DivX, a MPEG-4 digital video technology. Among its benefits is compression technology, which allows DivX equipped network cameras to store a month of video on a 20’gigabyte hard drive.
Directional Antenna
An antenna for wireless equipment which sends or receives a propugated radio signal on the same axis as the corresponding antenna on the other end (with line-of-sight visibility between the two whenever possible). While omni-directional antennas are great for short range broadcasts because of their versatility, high gain directional antennas are recommended for most long range wireless video applications.
Distribution Amplifier
A device that provides several isolated outputs from one looping or bridging input, and has a sufficiently high input burden and input-to-output isolation to prevent loading of the input source.
DMD
Digital micro-mirror device. A new video projection technology that uses chips with a large number of miniature mirrors, whose projection angle can be controlled with digital precision.
DNS
Dynamic Name Service is simply a database of IP addresses and Domain Names. This database is responsible for telling the internet how to route a request based only on a name and not an IP address.
Dome Camera
A type of camera with a dome-like shape. Most often used indoors. Some feature infrared lightning and some are designed to be tamper-proof, such as the Armor Dome Camera.
DOS
Disk operating system. A software package that makes a computer work with its hardware devices such as hard drive, floppy drive, screen, keyboard, etc.
Dot pitch
The distance in millimeters between individual dots on a monitor screen. The smaller the dot pitch the better, since it allows for more dots to be displayed and better resolution. The dot pitch defines the reaslution of a monitor. A high-resolution CCTV or computer monitor would have a dot pitch of less than 0.3 mm.
Drop-fram Time Code
SMPTE time code fo
Door Status Switch
A DSS is a switch used to monitor whether a door is in an opened or closed position.
Dropout
The loss of video signal from a magnetic tape playback head or worn or damaged tapes.
DSL (Digital Subscriber Line)
DSL is a digital telecommunications protocol that allows existing copper phone lines to be used for high-speed transfer of data between home and business end-users. xDSL refers to the various types of Digital Subscriber Lines which include: ADSL (Asymmetric DSL), SDSL (Single-line DSL), HDSL (High-data-rate DSL) and VDSL (Very-highdata-rate DSL). In theory, ADSL (the most common of these types), allows for download speeds of up to 9 Mbps and upload speeds of up to 640 Kbps. In reality, commercial performance is normally up to 1.544 Mbps download and 128 Kbps upload.
DSP (Digital Signal Processing)
These chips can compress video independent of the CPU, which avoids the need to draw processing power from the CPU, allowing it to focus on other applications and computing tasks.
DTMF (Dual Tone Multi-Frequency)
The scientific term for the Touch Tone signal used on telephones, it is the existing standard for the use of twisted wire pairs to send signals. Some PTZ cameras use DTMF signals in the transferring of telemetry information to the camera. This allows users to move the camera by dialing the number for that camera and then pressing buttons on their phone.
Dubbing
Transcribing from one recording medium to another.
Duplex
A duplex grants the ability to transfer data in and out of the recorder at the same time. In example, a full duplex DVR can continue capturing and recording images even while a different image is being displayed.
Duplex DVR
A duplex DVR is a DVR that can record and view/playback at the same time. Compare to a triplex DVR or a pentaplex DVR.
Digital Versatile Disk (DVD)
Sometimes called digital video disk. This is an optical disk the same size as a CD, used for storing data of various formats. Including video, audio and computer data. Direct
Drive (DD)
Some auto iris lenses require a DC signal from the camera. These are known as direct drive lenses.
DV-Mini - Mini digital video.
A new format for audio and video recording on small camcorders, adopted by the majority of camcorder manufacturers. Video and sound are recorded in a digital format on a small cassette (66×48×12 mm), superseding S-VHS and Hi 8 quality.
D-VHS
A new standard proposed by JVC for recording digital signals on a VHS video recorder.
DVR
Digital Video Recorder - A Digital Video Recorder, when applying to an CCTV security camera application, is a computer that coverts the incoming (analog) signal from cameras to digital, and compresses and stores the data. The DVR replaces the function of a multiplexer and a security VCR.
DVR Card
A DVR card is a device for installation in a home PC computer which converts that PC into a DVR digital video recorder by gathering video and compressing it into digital information onto a computer's hard disk drive. When all works well, this allows a home PC to record up to several surveillance cameras. However, due to reliability concerns and software glitches associated with Windows® as an operating system platform, using PCI cards to record video is not recommended. A home PC is designed to perform many operations at once, but relatively simple functions. Recording digital video requires enormous system resources like computer memory and processor attention. Complete DVR digital video recorders designed specifically to handle recorded video (and solely recorded video) offer the benefits of reliability, as well as simple setup and use, a computer card can never achieve.
DVST
Digital Video Storage & Transmission - name given to equipment that can compress pictures to a fraction of their former size for transmission over communication networks or for digital storage.
Dwell Time
The time a multiplexer or DVR stays on an individual camera before moving onto the next one in the sequence is known as dwell time.
Dynamic IP address
This is the rotation of IP addresses such that every time a user logs onto the Internet, their IP address changes. This is done for Internet security purposes, either by the user or by their ISP. This process can interfere with the use of networked devices such as Network IP Cameras because they normally require a static IP address to function properly.
Dynamic Range
The difference between the maximum acceptable signal level and the minimum acceptable signal level.
E
EBU
European Broadcasting Union.
EI (Electronic Iris)
Certain CCD security cameras utilize an electronic iris to electronically mimic a traditional auto iris. One drawback of an EI is that excessive light damages it over the long term.
EIA
is the standard monochrome video format used in North America, Japan, and some other places in the world. EIA products are also generally referred to as NTSC because nearly all NTSC products like televisions and VCRs can also handle black and white EIA video. Electronic Industries Association. American standard for B/W camera system.
Effpixels Pixels
concerns the operation of a camera's CCD image sensor. A CCD is comprised of hundreds of thousands of tiny pixel elements which translate light to a visible video image. But effpixels pixels must be distinguished from total pixels. Of the total number of pixels contained on a CCD image chip, some are not used for video imaging whatsoever. The number of effpixels pixels indicates exactly how many of the pixels are actively at work to deliver video. A higher number of effpixels pixels tends to indicate a higher tvres camera, though this number may not always describe actual video quality in the important categories of sharpness, color saturation and vividness, as well as low light performance.
Electronic Shuttering
This term applies to video cameras that compensate for moderate indoor changes in light without use of auto iris lenses.
ELC (Electronic Light Control)
Compensates for moderate light changes in indoor applications without the use of auto iris lenses. Select this mode when a fixed iris lens or manual iris lens is used.
Electronic Iris (EI)
is an electronic implementation of an auto iris. It uses electronics to simulate the effect of opening and closing the iris, by increasing or decreasing the effective shutter time of the camera.
E-mail notification
This is a feature of certain motion detecting Network IP Cameras. When activity is detected, they can email authorized users images or video.
Embedded operating system
Cameras with this can also operate as computers. With an OS like Linux installed, they can perform other tasks such as sending images to a web site via FTP, email notification, and being simultaneously accessible by multiple users.
EMI (Electro Magnetic Interference)
If improperly shielded, most electronic equipment causes EMI. The FCC sets the standards for electronic equipment shielding.
Encode
Seen in multiplexer terminology as the recording of images to tape.
Encoder
A device that superimposes electronic signal information on other electronic signals.
Enclosed Board Camera
(a.k.a. module camera) - This term refers to cameras with their electronic board circuitry enclosed or housed inside a protective metal or plastic casing. Enclosed board cameras are not as delicate as exposed board cameras (although all electronics should be handled carefully), but they are also slightly larger and heavier.
Encryption
The rearrangement of the bit stream of a previously digitally encoded signal in a systematic fashion to make the information unrecognizable until restored on receipt of the necessary authorization key. This technique is used for securing information transmitted over a communication channel with the intent of excluding all other than authorized receivers from interpreting the message. Can be used for voice, video and other communications signals.
ENG camera
Electronic News Gathering camera. Refers to CCD cameras in the broadcast industry.
EPROM
Erasable and programmable read only memory. An electronic chip used in many different security products that stores software instructions for performing various operations.
Equalizer
An electronic circuit that introduces compensation for frequency discriminative effects of elements within the television system, particularly long coaxial transmission systems.
Error Correction
Method employed by modems to ensure that data is transmitted and received error free.
Ethernet
Ethernet can send information either wirelessly (known as WiFi) or, more commonly, over wires. It runs at 10mbps, and all terminals connect to a single common bus (sometimes called a highway). It serves as the IEEE (Institute of Electrical and Electronics Engineers) 802.3 standard, which ensures that networks adhere to a particular set of technical standards. A new type, known as Fast Ethernet, or 100Base-T, runs at 100Mbps, and the newest type, Gigabit Ethernet, runs at 1gigabit per second.
Exposed Board Camera
This term refers to cameras with electronic board circuitry left exposed on the cameras without a housing or enclosure. These cameras are considered delicate and must be used and handled gently, but are great for some limited applications (like unmanned / radio-controlled vehicles, OEM applications, or body worn video use) because of their slim profile and low weight. In order to provide some degree of protection, all exposed board camera models found on this site come standard with 3M heat shrink coating. For a better protected miniature camera, please consider an enclosed board model.
Evidence Quality
Includes specifics such as DVR recordings set at a resolution rate so that faces, number plates etc. can be identified, and accurate time and date information displayed with each recording.
External Sync
The ability of electronic equipment (normally seen in cameras) to accept a synchronization signal from an external source and synchronize its self to it.
Extruded aluminum
This type of aluminum is used to construct housings for CCTV (closed circuit television) applications and provides the added benefits of increased strength, durability and resistance to harsher environmental conditions as compared to plastics.
F
Fast lens
Having a larger iris (and smaller F-stop), a fast lens gathers and transmits increased light to a surveillance camera.
FCC (Federal Communications Commission)
This United States commission regulates communications by setting rates, controlling broadcast licensing, and testing electronic equipment to RF (radio frequency) transmission and related standards.
FFT
Fast Fourier Transformation
Fence disturbance sensor
The perimeter fence around a site may have one of these installed around it for intrusion detection. These sensors can be interfaced with a CCTV switcher so that specific cameras are activated in an area where the disturbance is detected.
FI (Fixed Iris)
These widely used fixed focal length iris lenses are inexpensive and are found in smaller types of fixed CCTV security cameras, usually small case or dome cameras.
Fiber Optics
Also called optical fibers or optical fiber bundles. An assemblage of transparent glass fibers all bundled together parallel to one another. The length of each fiber is much greater than its diameter. This bundle of fibers has the ability to transmit a picture from one of its surfaces to the other around curves and into otherwise inaccessible places with an extremely low loss of definition and light, by a process of total reflection.
Field
One of the two equal but vertically separated parts into which a television frame is divided in an interlaced system of scanning. A period of 1/60 second separates each field start time.
Field of View
The maximum angle of view that can be seen through a lens or optical instrument. . A field of view calculator is used to determine the field of view with various distances and lens settings.
Firewall
A firewall is a software or hardware application installed on a home or office computer that is intended to prevent unauthorized users from accessing that computer. With hacking and network intrusions on the rise, they are becoming essential in protecting private information. Four popular types of firewall are packet filtering, application gateways, circuit-level gateways, and proxy servers. Although they can be difficult to configure correctly, they are a critical component to protect unauthorized access and hacking of IP based surveillance systems that are LAN based.
Fixed Lens
A fixed focus lens has one set focal length with a specific field of view which cannot be changed. Any camera without a varifocal or power zoom has a fixed focus lens. All cameras offered a Eyespyvideo.com with fixed lenses are focused to infinity. This means that although the user cannot manipulate the field of view, everything in the picture beyond a few inches will be clear and in focus. Objects simply get smaller as they move further away from the camera (unlike a camcorder which may be focused only on a small area with blurred vision of the video image in the foreground or background of that area).
Fixed focal length lens
A lens with a predetermined fixed focal length, a focusing control and a choice of iris functions.
Fiber
Optic Cable One of the video transmission ways, being used for a long distance transmission up to miles.
Film recorder
A device for converting digital data into film output. Continuous tone recorders produce color photographs as transparencies, prints or negatives..
Flange back
This refers to the distance from lens flange (the beginning of the lens mount) to the focal plane. The flange back measurement for C-mount lenses is 17.52mm, while CS-mount is 12.5mm.
Flash Memory
Or flash RAM (Random Access Memory). A type of constantly powered non-volatile memory that can be erased and reprogrammed in units of memory called blocks.
Flat Panel Antenna
An antenna for wireless with a flat antenna element contained inside a protective weatherproof housing. As a highly directional antenna, a flat panel is intended to send or receive a propugated radio signal on the same axis as the corresponding antenna on the other end (with line-of-sight visibility between the two whenever possible). While omni-directional antennas are great for short range broadcasts because of their versatility, high gain directional antennas are recommended for most long range wireless video applications.
Flicker
An annoying picture distortion, mainly related to vertical syncs and video fields display. Some flicker normally exists due to interlacing; more apparent in 50 Hz systems (PAL). Flicker shows also when static images are displayed on the screen such as computer generated text transferred to video. Poor digital image treatment, found in low-quality system converters (going from PAL to NTSC and vice versa), creates an annoying flicker on the screen. There are several electronic methods to minimize flicker.
FM
Frequency Modulation.
f-number
This is used to indicate image brightness as formed by the lens and controlled by the iris. The smaller the f-number, the brighter the image is.
Focal Length
Of a lens, the distance from the focal point to the principal point of the lens. Focal Length tells you the strength of the lens. The longer the Focal Length the narrower Angle of View, the shorter the Focal Length the wider the Angle of View. The distance between the centre of a lens, or its secondary principal point and the imaging sensor. Lower lengths give a greater field of view and less magnification. Longer lengths give a narrower field of view and greater magnification. The table below gives an approximate value for the angle of the field of view for lenses of various focal lengths. 30° is considered to be a normal view, telephoto (longer) lenses have lower angles. Most CCTV cameras have one of the 3 sizes of imaging devices listed below, 1/4", 1/3" or 1/2". As you can see, this makes a big impact when choosing lenses.
Focal Length
Imaging Device Size
1/4" 1/3" 1/2"
2.8 mm 64° 80° 97°
4.0 mm 45° 60° 74°
6.0 mm 30° 38° 57°
8.0 mm 23° 30° 40°
12.0 mm 15° 20° 30°
16.0 mm 11° 15° 22°
50.0 mm 4° 5° 7°
Focal Plane
A plane (through the focal point) at right angles to the principal point of the lens.
Focal Point
The point at which a lens or mirror will focus parallel incident radiation.
Focusing control
A means of adjusting the lens to allow objects at various distances from the camera to be sharply defined.
Foot-candela
An illumination light unit used mostly in American CCTV terminology. It equals ten times (more precisely, 9.29) of the illumination value in luxes.
Footlambert (FL)
A unit of luminance equal to 1/candela per square foot or to the uniform luminance at a perfectly diffusing surface emitting or reflecting light at the rate of one lumen per square foot. A lumen per square foot is a unit of incident light and a footlambert is a unit of emitted or reflected light. For a perfectly reflecting and perfectly diffusing surface, the number of lumens per square foot is equal to the number of footlamberts.
Fourier Transformation
Mathematical transformation of time domain functions into frequency domain.
FPS
Frames Per Second - in digital video applications, refers to the number of video images that can be captured, displayed, or recorded in a second. Also referred to as the 'frame rate' or 'refresh rate'.
FPS Display Rate
(a.k.a. screen refresh rate) indicates the number of frames per second a VCR or DVR recorder will display on a monitor for simultaneous viewing. Please DO NOT CONFUSE this specification with FPS Record / Playback Rate. The rate at which each camera is displayed is often NOT the same as the number of frames per second the recorder captures for playback. Many DVR sellers flash "real-time display rate" or "30 frames / sec. display rate" but do not in fact offer realtime playback of recorded video.
FPS Record Rate
describes exactly how many frames per second a video recorder can actually capture. Analog recorders like VCRs can easily record in realtime (30 frames / sec. for standard NTSC) or timelapse (fewer than 30 frames / sec. for NTSC). Many digital DVR recorders, however, cannot record actual realtime video. Many sellers try to mislead consumers by advertising FPS Display Rate instead of actual record rate. For most situations, recording rate is the spec to pay attention to. However, please note specifications for digital video equipment are not the only numbers to rely on. In fact, many DVR recorders outperform their specifications upon real world testing while other low quality units often record at a much slower rate than their specs claim.
Frame
The total area, occupied by the television picture, which is scanned while the picture signal is not blanked.
Frame Frequency
The number of times per second that the frame is scanned. The U.S. standard is 30 frames per second.
Frame store
An electronic method of capturing and storing a single frame of video. All slow scan transmitters include a frame store that holds the picture at the moment of alarm, while the control is being dialed up. When the link is confirmed, the picture is transmitted.
Frame switcher
Another name for a simple multiplexer, which can record multiple cameras on a single VCR (and play back any camera in full screen) but does not have a mosaic image display.
Frame synchronizer
A digital buffer that, by storage and comparison of sync information to a reference and timed release of video signals, can continuously adjust the signal for any timing errors.
Frame Transfer
A CCD imager where an entire matrix of pixels is read into storage before being output from the camera. Differs from Interline Transfer where lines of pixels are output
Frequency
is the number of competed cycles of an electronic signal that occur in a given length of time. Frequency is usually measured in cycles per second (Hertz, Hz). For most CCTV industry equipment, frequency is used to describe the RF radio frequency at which wireless equipment operates. Frequency can also be used to describe the cycles of electrical current for the signal system.
Frequency Interlace
The method by which color and black and white sideband signals are interwoven within the same channel bandwidth.
Frequency Response
The range of band of frequencies to which a unit of electronic equipment will offer essentially the same Characteristics
Frames per Second
(FPS) describes the number of full video frames displayed or recorded within one second. True real time video consists of 30 frames / sec. for NTSC format and 25 frames / sec. for PAL format. Be sure not to confuse frames per second with "fields per second" or "images per second". A complete frame of video is compiled of two separate images (or fields), so the number of fields in one second is always twice the number of frames per second..
Front Porch
The portion of a composite picture signal which lies between the leading edge of the horizontal blanking pulse and the leading edge of the corresponding sync pulse.
f/Stop
Also called F Number and F System. Refers to the speed or ability of a lens to pass light. It is calculated by dividing the focal length of the lens by its diameter.
FSK
Frequency Shifted Keying - a form signaling employed by coaxial born telemetry equipment.
FTP (File Transfer Protocol)
FTP is a client/server protocol used for the exchange of data between computers. Network cameras with an embedded operating system use FTP to send camera images to an authorized user’s computer or web site.
Full Picture Update
Used to describe video transmission products that send the total image on each update.
G
Gain
An increase in voltage or power, usually expressed in dB.
Gamma
A numerical value, or the degree of contrast in a television picture, which is the exponent of that power law which is used to approximate the curve of output magnitude versus input magnitude over the region of interest.
Gamma Correction
To provide for a linear transfer characteristic from input to output device.
Genlock
A device used to lock the frequency of an internal sync generator to an external source.
Ghost
A spurious image resulting from an echo. Also known as ghosting, this is when an image moved across a computer screen leaves a brief lingering shadow of itself where it had just been, creating a kind of smear or blur. Lower quality computer screens often leave ghosts. Technically, the secondary visual signal has been created and received either earlier or later than the primary signal itself.
GHZ
Gigahertz
GIGA
Order of magnitude 10-9
GIP
Granded Index File - a measurement shown in the form of a diagram which illustrates how the quality of glass in fibre optics, alters gradually from the densest at the core to the optically less dense cladding.
GLT
Ground Loop Transformer - an isolation transformer with no direct contact between input and output.
Gray Scale
Variations in value from white, through shades of gray, to black on a television screen. The gradations approximate the tonal values of the original image picked up by the TV camera.
Ground Loop
This type of picture interference is caused when the ends of a video cable have differing ground potential, causing an AC current. This is either a black shadow bar onscreen or a tearing in the top corner of the picture results. The use of ground loop insulators prevents this problem.
GUI (Graphical User Interface)
Pronounced ‘gooey’, this is the interface between the computer and the matrix switcher. Active areas of the computer screen are programmable, feature menus, icons, are clickable, and able to activate devices such as VCRs and matrix switchers. Essentially, the GUI makes the CCTV system easier to use.
H
HAD
Hole accumulated diode. A type of CCD sensor with a layer designed to accumulate holes (in the electronic sense), thus reducing noise level.
Hardware Compression
Video data compression taken place in specialized purpose built microchips.
Hardwired
Direct connection between one product and another, used for control equipment in simple systems.
HDD
Hard disk drive. A magnetic medium for storing digital information on most computers and electronic equipment that process digital data.
HDDTV
High definition digital television. The upcoming standard of broadcast television with extremely high resolution and aspect ratio of 16:9. It is an advancement from the analog high definition, already used experimentally in Japan and Europe. The picture resolution is nearly 2000×1000 pixels, and uses the MPEG-2 standard.
HDTV
High definition television. It usually refers to the analog version of the HDDTV. The SMPTE in the US and ETA in Japan have proposed a HDTV product standard: 1125 lines at 60 Hz field rate 2:1 interlace; 16:9 aspect ratio; 30 MHz RGB and luminance bandwidth
HDD Capacity indicates the amount of information which can be stored on hard disk drive. This figure is measured in bytes. 1 GB = 1016 MB = 1032256 KB = 1048772000 bytes. HDD Speed indicates the speed at which a hard disk drive is capable of encoding information. While many DVR sellers only use inexpensive, slow generic HDD drives (typically 5400 RPM with no buffer in place), DVR recorders are only equipped with 7200 RPM hard disk drives with 8 MB buffers from trusted brand names like Seagate, Western Digital, and Maxtor.
Headend
The electronic equipment located at the start of a cable television system, usually including antennas, earth stations, preamplifiers, frequency converters, demodulators, modulators and related equipment.
Helical scan
A method of recording video information on a tape, most commonly used in home and professional VCRs.
Hertz
A Hertz (Hz) is the unit used to measure frequency, with 1 Hz equal to 1 cycle per second.
Horizontal Drive (also Horizontal sync)
This signal is derived by dividing sub-carrier by 227.5 and then doing some pulse shaping. The signal is used by monitors and cameras to determine the start of each horizontal line.
Horizontal resolution
This measures the maximum amount of individual picture elements recognizable in a single scanning line.
Homing
a term used to describe a type of automatic sequential switcher, which will stop sequencing and remain on a single CCTV camera input displayed on the monitor when a switch or button is depressed. This switcher has only one monitor output.
Housing
Covering or container featured on some cameras designed to protect from it from the weather.
Herringbone
Patterning caused by driving a color-modulated composite video signal (PAL or NTSC) into a monochrome monitor.
Horizontal retrace
At the end of each horizontal line of video, a brief period when the scanning beam returns to the other side of the screen to start a new line.
Horizontal sync pulse
The synchronizing pulse at the end of each video line that determines the start of horizontal retrace.
Hertz
An unit that measures the number of certain oscillations per second. Housings, environmental. Usually refers to cameras’ and lenses containers and associated accessories, such as heaters, washers and wipers, to meet specific environmental conditions.
HS
Horizontal sync.
Hue (tint, phase, chroma phase)
One of the characteristics that distinguishes one color from another. Hue defines color on the basis of its position in the spectrum, i.e., whether red, blue, green or yellow, etc. Hue is one of the three characteristics of television color: see also Saturation and Luminance. In NTSC and PAL video signals, the hue information at any particular point in the
HTML (HyperText Markup Language)
HTML is the language used in the creation of WWW pages, with use of hyperlinks and markup for text formatting.
HTTP (HyperText Transfer Protocol)
This is the protocol utilized to transmit and request information from WWW servers to browsers, either online or over networks.
Hub
Networks rely on devices called hubs to connect multiple computers together into a LAN. Standard hubs share the bandwidth across all ports (so an eight port 100 Mps hub allocates this 100 Mps among the eight ports), while switching hubs are able to give each individual port a dedicated bandwidth amount (so these same eight ports could conceivably each receive a full 100 Mps of bandwidth on a switching hub).
Hue
Corresponds to colors such as red, blue, etcetera.
Hum
Electrical disturbance at the power supply frequency or harmonics thereof.
Hum bug
Another name for a ground loop corrector.
Hyper-HAD
An improved version of the CCD HAD technology, utilizing on-chip micro-lens technology to provide increased sensitivity without increasing the pixel size.
H.264
is a standard for video compression. It is also known as MPEG-4 Part 10, or AVC (for Advanced Video Coding). It was written by the ITU-T Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG) as the product of a partnership effort known as the Joint Video Team (JVT). The ITU-T H.264 standard and the ISO/IEC MPEG-4 Part 10 standard (formally, ISO/IEC 14496-10) are jointly maintained so that they have identical technical content.
H.264
The latest video compression standard, H.264, is expected to become the video standard of choice in the coming years. It has already been successfully introduced in electronic gadgets such as mobile phones and digital video players. For the video surveillance industry, H.264 offers new possibilities to reduce storage costs and to increase the overall efficiency. H.264 (sometimes referred to as MPEG-4 Part 10/AVC) is an open, licensed standard that supports the most efficient video compression techniques available today. Without compromising image quality, an H.264 encoder can reduce the size of a digital video file by more than 80% compared with the Motion JPEG format and as much as 50% more than with the traditional MPEG-4 Part 2 standard. It is the magnitude of these numbers that makes H.264 highly relevant for video surveillance applications. Bit rate comparison for a 115 seconds video stream, given the same level of image quality, among different video standards. The H.264 encoder was at least three times more efficient than an MPEG-4 encoder with no motion compensation and at least six times more efficient than Motion JPEG. Reduced storage and bandwidth costs One immediate benefit of the drastically reduced file sizes is the impact on storage and bandwidth requirements. For the same amount of video data, with the same image quality, a video surveillance system supporting H.264 compression will basically reduce the storage cost and bandwidth occupancy by at least 50% compared to when using conventional compression technologies. As the systems grow larger, and the requirements for high resolution images in combination with high frame rates increase, H.264 will be a key differentiator between various system solutions. Higher resolution and frame rate Depending on application needs, there are various ways to benefit from the impressive compression rate of H.264. Today, it is common to choose a limited frame rate or lower resolution in order to stay within the specified storage limitations of an application. This has a negative impact on the video images, which become either blurry or less detailed. Introducing video surveillance equipment that support H.264 compression in such an application will enable several combinations of increased frame rate and image resolution, thus providing higher image quality. Accelerating use of megapixel cameras H.264 is expected to accelerate the adoption of megapixel cameras within the surveillance industry. One of the current trade-offs of megapixel cameras is the large size of the recorded video data. As mentioned above, H.264 reduces the large file sizes without compromising image quality. It is likely that the highly efficient compression technology find the quickest traction in applications where there are demands for both high resolution and high frame rates, such as in the surveillance of airports, retail stores, banks and casinos. Looking ahead H.264 presents a huge step forward in video compression technology. With support from many industries and applications for consumer and professional needs – e.g. QuickTime, Flash, YouTube, iPod and Play- Station 3 – H.264 is expected to replace other compression standards and methods in use today. As the format becomes more broadly available in video surveillance equipment, system designers and integrators will need to make sure that the products and vendors they choose support this new open standard. Origin of H.264 H.264 is the result of a joint project between the International Telecommunications Union’s Video Coding Experts Group (VCEG) and the ISO/IEC Moving Picture Experts Group (MPEG). ISO stands for International Organization for Standardization and IEC is an organization that oversees electronic and electrical standards. H.264 is the name used by ITU-T, while ISO/IEC has named it MPEG-4 Part 10/AVC since it is presented as a new part in its MPEG-4 suite. Jointly defined by standardization organizations in the telecommunications and IT industries, H.264 is expected to be more widely adopted than previous standards.
I
IDE
Interface device electronics. Software and hardware communication standard for interconnecting peripheral devices to a computer.
I/O
Input/Output.
I/P
Input. A signal applied to a piece of electric apparatus or the terminals on the apparatus to which a signal or power is applied.
I2R
Formula for power in watts (W), where I is current in amperes (A), R is resistance in ohms (W).
IEC
International Electrotechnical Commission (also CEI).
IFrame
An IFrame is a complete image frame (known as an Intra Frame) in MPEG encoding that is coded without reference to other pictures. Compression is achieved by reducing spatial redundancy in the image, but not temporal redundancy.
Imaging device
A vacuum tube or solid state-device in which the vacuum tube light-sensitive face plate or solid-state light-sensitive array provides an electronic signal from which an image can be created.
Image Intensifier
A device coupled by fiber optics to a TV image pickup sensor to increase sensitivity. Can be single or multi stage.
Image Plane
The plane at right angles to the optical axis at the image point.
Image Sensor
indicates the type of semiconductor which handles video processing inside of a camera. Older CCTV cameras used tubes to process light information. CMOS and CCD image sensors are the most widely available for security cameras in today's market. CCD cameras provide by far the highest quality video of any type of image sensor.
Impedance (input or output)
The input or output characteristic of a system component that determines the type of transmission cable to be used. The cable used must have the same characteristic impedance as the component. Expressed in ohms. Videodistribution has standardized on 75-ohm coaxial and 124-ohm balanced cable.
Incident Light
The light that falls directly on an object.
Index of refraction
This ratio measures the angle of incidence to the angle of refraction of light, with a denser medium bending more light and having a higher index of refraction.
Infrared
Infrared radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means "below red", red being the color of visible light with the longest wavelength.
Infrared Camera
Infrared Security Cameras have special infrared lights installed around the outside of the camera lens. Through use of this special light the camera can capture a good picture even in total darkness.
Infrared detector
This is an alarm that uses infrared light to detect nearby movement.
Infrared illuminator
A light source working in the infrared frequency range is called an infrared illuminator.
Infrared radiation
Invisible to the human eye, this electromagnetic radiation has a wavelength of greater than 750 manometers.
IR Cutoff Filter
A filter inside the camera that moves behind the lens when it gets dark. A camera with an IR Cut Filter will produce very high quality images in low light conditions.
Injection molded plastic
Smoked or tinted plastic (but still translucent) is melted into a liquid from pellets and injected into a “dome-shaped” mold to construct security camera dome housings.
Input - Same as I/P.
Inserter
(also alphanumeric video generator) - A device for providing additional information, normally superimposed on the picture being displayed; this can range from one or two characters to full-screen alphanumeric text. Usually, such generators use the incoming video signal sync pulses as a reference point for the text insertion position, which means if the video signal is of poor quality, the text stability will also be of poor quality.
Insertion Loss
The signal strength loss when a piece of equipment is inserted into a line.
Interlacing
PAL video signals transmit odd and even lines alternately. This is a 2:1 interlace. The two sets of lines are combined to form each single frame.
Interference
Extraneous energy which tends to interfere with the reception of the desired signals.
Interleaving
Some alarms and security systems use the process of interleaving to add extra frames from alarmed cameras to a time multiplexed sequence while the alarm is activated. This prioritizes the view from alarmed cameras in the sequence of camera views.
Interline Transfer
A technology of CCD design, where rows of pixels are output from the camera. The sensor's active pixel area and storage register are both contained within the active image area. This differs from "frame transfer" cameras that move all active pixels to a storage register outside of the active area.
Interlacing
PAL video signals transmit odd and even lines alternately. This is a 2:1 interlace. The two sets of lines are combined to form each single frame.
Interlaced Scanning
A scanning process for reducing image flicker in which the distance from center to center of successively scanned lines is two or more times the nominal line width, and in which the adjacent lines belong to different fields.
Internal sync
The internal generation of sync pulses in a camera using a crystal controlled oscillator. This is needed on non-mains powered cameras.
INT
Internal sync mode that sets to internal 2:1 interlace.
Input Voltage
indicates the type of electrical current (AC or DC) and the voltage required to safely and effpixelsly power a device.
IP
Internet Protocol Address is a unique address given to certain computer or electronic devices. An IP address is necessary for devices to identify and communicate with each other. An IP address is required for positive unique identification of any device on a network or the internet.
IP address
This is a numeric address that is then translated into a domain name by the DNS (domain name server). When we type in a website’s name, the computer translates this into its IP address, which is a unique 32-bit number. The TCP/IP protocol then uses it for routing the data packets to their destinations. Each host has a unique IP address.
IP Camera (or Network Camera)
This signal from an IP camera is delivered over an IP network. The camera digitizes the images, compresses them, and then sends them over the network (if this sounds similar to a webcam, that’s because there is digital webcam technology contained within a network camera). But a typical IP network camera is much more advanced as compared to a consumer web camera which needs to be attached to a computer to operate. IP enabled security cameras usually offer a browser interface so that the user can operate and view the video remotely over the Internet. A DVR system is often comprised of an IP camera and a NVR.
IPCCTV
Internet Protocol Closed Circuit Television
IP Waterproof Rating (IP66 - IP68)
IP ratings are a BSi standard measurement for how waterproof something is. Many cameras or camera housings are designed for outdoor use, and therefore need to be waterproof to some degree. The details of the tests are defined in BS EN 60529 : 1992. The IP number has two digits, and optional letters after them.
IRE - Institute of Radio Engineers.
Units of measurement dividing the area from the bottom of sync to peak white level into 140 equal units. 140 IRE equals 1Vpp. The range of active video is 100 IRE.
IR light
Infrared light, invisible to the human eye. It usually refers to wavelengths longer than 700 nm. Monochrome (B/W) cameras have extremely high sensitivity in the infrared region of the light spectrum.
IR Infrared Wavelength
indicates the specific frequency of light (measured in nM - nanometers) an Infrared illuminator emits.
IR Illumination Range
indicates the effpixels range at which a monochrome CCD camera can utilize the Infrared light from an illuminator and create an image. Eyespyvideo.com offers several camera models with built-in Infrared illuminators capable of casting light more than 40 feet in front of the camera. 40+ feet is therefore the IR illumination range for those cameras. Just like visible lights, more intense Infrared lighting sources will provide a larger illumination area and range.
Iris
An adjustable aperture built into a camera lens to permit control of the amount of light passing through the lens.
ISDN (Integrated Services Digital Network)
ISDNs are digital telecommunications lines that transmit voice and digital network services. Many telephone companies provide them, due to their superior reliability and speed (up to 128K) over analog modems. The ISDN standard improves compatibility for the integrated digital transmission of voice, video, and data over normal copper telephone wires, which allows for better quality and speeds. There are two primary types of ISDN: BRI (Basic Rate Interface) and PRI (Primary Rate Interface). PRI is faster, with speeds on par with T-1 circuits.
Isolation Amplifier
An amplifier with input circuitry and output circuitry designed to eliminate the effects of changes made at either upon the other.
ISIT
Intensified Silicon Intensified Target - Usually used for extreme low light CCTV cameras or X-ray machines.
ISO
International Standards Organization
ITU (International Telecommunications Union)
Currently, 113 countries participate in the ITU, which is an agency of the United Nations. Existent since 1865, the ITU is responsible for developing international telecommunications for networked telecommunications. The ITU-R is a subchapter, and is responsible for managing radio frequency spectrum (including television and video) standards
J
Jitter
Small, rapid variations in a waveform due to mechanical disturbances or to changes in the characteristic of components. Supply voltages, imperfect synchronizing signals, circuits, etc.
Joystick
PTZ controllers utilize this stick as a control device for pan and tilt movement of a PTZ security camera’s pan and tilt head.
JPEG is a standard for coding/compression of still pictures. It is used in the CCTV systems to compress and store individual frames of video. JPEG was developed by the Joint Photographic Experts Group. This is short for Joint Photographic Experts Group international – a good and very popular standard for still images that is supported by many modern programs. With JPEG, decompression and viewing can be done from standard Web browsers. JPEG compression can be done at different user-defined compression levels, which determine how much an image is to be compressed. The compression level selected is directly related to the image quality requested. Besides the compression level, the image itself also has an impact on the resulting compression ratio. For example, a white wall may produce a relatively small image file (and a higher compression ratio), while the same compression level applied on a very complex and patterned scene will produce a larger file size, with a lower compression ratio.
JPEG2000 Another still image compression standard is JPEG2000, which was developed by the same group that also developed JPEG. Its main target is for use in medical applications and for still image photography. At low compression ratios, it performs similar to JPEG but at really high compression ratios it performs slightly better than JPEG. The downside is that support for JPEG2000 in Web browsers and image displaying and processing applications is still very limited.
K
kb/s
Kilobits per second. Thousand bits per second. Also written as kbps.
Kelvin
One of the basic physical units of measurement for temperature. The scale is the same as the Celsius, but the 0ºK starts from -273ºC. Also the unit of measurement of the temperature of light is expressed in Kelvins or K. In color recording, light temperature affects the color values of the lights and the scene that they illuminate.
K factor
A specification rating method that gives a higher factor to video disturbances that cause the most observable picture degradation.
kHz
Kilohertz. Thousand Hertz.
Kilobaud
A unit of measurement of data transmission speed equalling 1000 baud.
KiloByte
1024 bytes.
L
Lag
Image retention that occurs in a video image when rapid motion of the camera or viewed object leaves a trail.
Lambertian source or surface
A surface is called a Lambert radiator or reflector (depending whether the surface is a primary or a secondary source of light) if it is a perfectly diffusing surface.
LAN (Local Area Network)
A LAN is a high-speed network connecting computers that are nearby (probably in the same building), and offers differing connection protocol options.
Laser
A source of exceptionally pure light which can consist of a single wavelength concentrated into single beam, used to transmit IR lighting through fiber optic cable.
Latency
The speed of a network is dependent on both latency and bandwidth, with latency referring to the time needed for an IP packet to travel from source to destination. Wide bandwidth and low latency are preferable.
Leased Line
A telephone connection giving a permanent point to point link.
LED (Light Emitting Device)
Monochrome surveillance cameras use LEDs to provide infrared light. An LED creates an infrared light frequency when stimulated by an electric charge.
Lens
A transparent optical component consisting of one or more pieces of optical glass with surfaces so curved (usually Spherical), that they serve to converge or diverge the transmitted rays of an object, thus forming a real or virtual image of that object.
Lens Preset Positioning
Follower Pots are installed on lens that allows feedback to the controller information relevant to zoom and focus positioning allowing the controller to quickly adjust to a preselected scene and arrive in focus at the proper focal length automatically.
Lens Selection - Atss offers many lens choices, but they vary by camera. At the bottom of each camera's specifications, its optional lenses are listed. For lens exchangeable cameras, there are a wide variety of lenses to choose from. In order to take the confusion out of selecting a lens, please click here to view a lens chart for 1/3" CCD cameras. So long as the distance and video target area have been determined, this chart makes lens selection a breeze
Lens Speed
Refers to the ability of a lens to transmit light, represented as the ratio of the focal length to the diameter of the lens. A fast lens would be rated <f/1.4; a much slower lens might be designated as> f/8. The larger the f number, the slower the lens.
Level control
Level control is control of the main iris, and sets the auto-iris circuit to a specific video level of the user’s choice. The iris is therefore set to maintain this video level no matter what the light condition may be. A high level opens the iris; a low level closes it.
Light
Electromagnetic radiation detectable by the eye, ranging in wavelength from about 400 to 750 nm.
Light sensor
Often used to turn infrared illuminators on or off, this device is triggered when it detects a pre-set amount of light, and helps cope with low (or no) level light conditions.
Limit switch
A security camera’s pan and tilt head with one of these devices installed (either inside or outside it) is limited in the angles it can move.
Line Amplifier
An amplifier for audio or video signals that feeds a transmission line; also called program amplifier.
Line Fed Camera refers to the use of equipment that can provide power to the camera and take the video signal along the same cable. It normally involves placing an "encoder" unit at one end and a "decoder" unit at the other. These units effectively combine and then split the power from the video signal at either end of the cable run.
Line locked
The sync pulses of cameras are locked to the AC mains frequency.
Line powered
A camera in which the power is supplied along the same coaxial cable that carries the video signal.
Line-of-sight (a.k.a. LOS) Range refers to the ideal broadcast range of wireless audio/video link (transmitter and receiver) systems. Line-of-sight means the range when there is a visible pathway between the transmitter antenna and the receiver antenna. As well, the line-of-sight specification indicates performance under absolute best conditions. Please be aware that just like home cordless telephones, TV reception, and cellular phone reception, wireless audio/video equipment can often be less than perfect! All wireless products are subject to limitations and vulnerabilities due to many potential variables.
LL L
ine Lock mode LUX Lumens per Square Meter; unit of illumination amount
Linux
Linux is an open source UNIX implementation, and a popular alternative to the Windows operating system. It is often used in embedded operating systems found in advanced Network IP Cameras. Linux is freeware.
Loop frame store
The principle is that a series of video frames is compressed and stored in a continuous loop. This records a certain number of frames and then records over them again and again until an alarm signal is received. When this happens, it carries on recording for a dozen frames of so and then stops. This means that frames before and after the incident are recorded. This eliminates the boring searching through hours of video tape and concentrates on the period of activity.
Liquid Crystal Display (LCD)
This is a technology used for flat screen displays. Aside from being smaller and lighter, it also has the advantage of using less power than traditional cathode ray tube screens.
Lock Status Sensor (LSS)
Relay type to operate the LED wth an SPDT switch to indicate low voltage and tampering of the lock face locally or to a remote monitoring location.
Looping
refers to connecting an additional device in parallel with an existing video cable. For example, when driving a video recorder as well as a monitor from the same video signal, simply by T'ing off the cable.
Loop Through
Also called looping. The method of feeding a series of high impedance circuits (such as multiple monitor/displays in parallel) from a pulse or video source with a coax transmission line in such a manner that the line is bridged (with minimum length stubs) and that the last unit properly terminates the line in its characteristic impedance. This minimizes discontinuities or reflections on the transmission line.
Loss
A reduction in signal level or strength, usually expressed in dB. Power dissipation serving no useful purpose.
Loss Prevention
Best summarized as ‘not having anything stolen’, loss prevention is the practice of securing devices or information from theft or loss. Video surveillance is a common practice in preventing theft or other losses of property like vandalism.
Low-Frequency Distortion
Distortion effects which occur at low frequencies. In television, generally considered as any frequency below the 15.75-kHz line frequency.
Low Light
Refers to very dim lighting, even 'normal' darkness. Complete darkness is 0 lux. Infrared cameras work well in very low light conditions.
Lumen (LM)
The unit of luminous flux. It is equal to the flux through a unit solid angle (steradian) from a uniform point source of one candela or to the flux on a unit surface of which all points are at a unit distance from a uniform point source of one candela.
Lumen/FT2
A unit of incident light. It is the illumination on a surface one square foot in area on which a flux of one lumen is uniformly distributed, or the illumination at a surface all points of which are at a distance of one foot from a uniform source of one candela.
Luminance
Luminous intensity (photometric brightness) of any surface in a given direction per unit of projected area of the surface as viewed from that direction, measured in footlamberts (fl).
Luminance Signal
That portion of the NTSC color television signal which contains the luminance or brightness information.
LUT - Look-up table.
A cross-reference table in the computer memory that transforms raw information from the scanner or computer and corrects values to compensate for weakness in equipment or for differences in emulsion types.
Lux
International System (Sl) unit of illumination in which the meter is the unit of length. One lux equals one lumen per square meter. This is a measure of the amount of light striking a surface. i.e. the luminus flux density at a surface. One lux is one lumen per square metre. Cameras for use in good lighting conditions, or in daylight would normally be rated at 2 Lux or more. Cameras with a Lux rating of 0.2 Lux or less would be considered low-light cameras. It is not possible to get good colour definition in low light levels, so in general low light cameras are always monochrome. However, day/night cameras use electronics to switch from colour during the daytime, to monochrome during night or low light conditions. Many low light cameras are also infra-red sensitive, so that infra-red illumination can be used. Particularly useful in zero light conditions.
M
MAC
Multiplexed analog components. A system in which the components are time multiplexed into one channel using time domain techniques, i.e., the components are kept separate by being sent at different times through the same channel. There are many different MAC formats and standards
Manual iris lens:
A lens with a manual adjustment to set the iris opening (F-stop) to a given position. Generally used for relatively constant lighting applications.
Matrix
A logical network configured in a rectangular array of intersections of input/output channels
Matrix Switcher
A combination or array of electromechanical or electronic switches which route a number of signal sources to one or more designations.
MATV
Master antenna television.
Maximum Recording Time
indicates the longest continuous duration of time which could be recorded onto storage media using a VCR or DVR video recorder. Maximum recording time for ALL recorders will depend on the user setting for timelapse or realtime recording and the amount of storage media capacity. Maximum recording time for DVR recorders is also dependent on tvres settings as well as hard disk drive capacity. Maximum recording time for analog VCR recorders will depend on the size cassette tape, usually VHS, which is installed in the recorder.
MB - Megabyte.
Unit of measurement for computer memory consisting of approximately one million bytes. Actual value is 1,048,576 bytes. Kilobyte × Kilobyte = Megabyte.
MB/s
Megabytes per second. Million bytes per second or 8 million hits per second. Also written as MBps.
Mb/s
Megabits per second. Million bits per second. Also written as Mbps.
MCL
Maximum camera length.
Mechanical Focus
refers to the process of manually setting the focus on a lens
MFD
Mode Field Diameter - Term used in fiber optics.
MHZ
Megahertz
Micro Camera
Very small cameras designed to work in covert applications where you don't want people to know that the camera is there. Also called 'hidden cameras'
Microwave
One definition refers to the portion of the electromagnetic spectrum that ranges between 300 MHz and 3000 GHz. The other definition is when referring to the transmission media where microwave links are used. Frequencies in microwave transmission are usually between 1 GHz and 12 GHz.
Microwave Transmission
Method of sending video signals and/or data over free space, longer distances than IR transmission.
Micro Board Lenses
are standard lenses for many cameras. These types of lenses are visible (not easily hidden like a pinhole lens) and range in size from 14mm to 25mm in diameter. Because it is physically larger than a pinhole lens, a micro board lens is able to accept more available light to provide the lowest possible low light performance.
Milliamps
(mA) is a measure of electrical current power consumption. 1 amp (A) = 1000 milliamps (mA).
Milliwatts (mW) is a measure of RF radio frequency energy output. This term is most commonly applied to the RF output power of wireless A/V transmitters. For these types of devices, a higher number of milliwatts of output power indicates a more powerful (and usually further broadcasting) transmitter.
Mimic panel
This panel displays a site’s layout, including the location of surveillance cameras. When the panel is interfaced with a switcher, it can be used to switch any specific camera to the monitors.
Mini-DIN
Multi-wire cable with Mini-DIN connectors at both ends. Usually has 4 inner wires.
Minimum scene illumination
This information (found on a camera’s data sheet) displays the minimum light level the particular camera needs in order to provide an acceptable monitor picture.
JPEG (Motion JPEG)
Even though it’s not as efficient as MPEG-4, the MJPEG is still an effective way of creating video from the sequencing of JPEG images. The video from store security cameras often uses this method when being formatted.
MMS (Microsoft Media Services)
MMS is the first streaming protocol created for the Microsoft Windows Media Player.
MOD (Minimum Object Distance)
This refers to the closest an object can be to the vertex of the lens and still be in focus. The wider the lens angle, the smaller the MOD.
MODE
Path taken by light rays along fiber optic cable.
Modem
This popular term is made up of two words: modulate and demodulate. The function of a modem is to connect a device (usually computer) via a telephone line to another device with a modem.
Modulation
The process or results of the process, whereby some characteristic of one signal is varied in accordance with another signal. The modulated signal is called the carrier. The carrier may be modulated in three fundamental ways: by varying the amplitude, called amplitude modulation; by varying the frequency, called frequency modulation; by varying the phase, called phase modulation.
Moiré pattern
An unwanted effect that appears in the video picture when a high-frequency pattern is looked at with a CCD camera that has a pixel pattern close (but lower) to the object pattern.
Monitor
A unit of equipment that displays on the face of a picture tube the images detected and transmitted by a television camera.
Monitor Screen Size
indicates the actual physical size of a monitor's viewing screen. However, this measurement is often different than the actual part of the monitor which produces a picture. The monitor viewing size spec describes the size of the picture on a monitor.
Monitor Viewing Size
indicates the size of a monitor's actual visible picture
Monochrome
Black and white with all shades of gray.
Monochrome Signal
In monochrome television, a signal wave for controlling the brightness values in the picture. In color television, that part of the signal wave which has major control of the brightness values of the picture, whether displayed in color or in monochrome.
Monochrome Transmission
The transmission of a signal wave which represents the brightness values in the picture, but not the color (chrominance) values.
MOS
Metal Oxide Semiconductor - A form of CCD imager used in CCD cameras.
Motion Detection
A feature in some VCRs and DVRs to only begin recording video if something in the image moves or changes. Good for monitoring an area that is not heavily trafficked, and saves a lot of hard drive space.
Motorised Lens
A camera lens equipped with small electric motor that enables focusing lens, opening or closing the iris diaphragm, or changing the focal length.
Mounting Bracket
Various different kinds of mounting brackets are used to install cameras to the wall or ceiling.
MPEG (or MPG)
Pronounced "em-peg" and stands for "Motion Picture Experts Group" who designed the standard. This is a standard way of compressing audio and video files. (It's also the technology behind the now world-famous MP3 music files.)
MPEG-1
Standard for compressing progressive scanned images with audio. Bit rate is from 1.5 Mbps up to 3.5 Mbps.
MPEG-2
The standard for compression of progressive scanned and interlaced video signals with high quality audio over a large range of compression rates with a range of bit rates from 1.5 to 100 Mbps. Accepted as a HDTV and DVD standard of video/audio encoding.
MPEG-4
MPEG4 has a newer codec and supports 3D content, low bit rate encoding, and support for Digital Rights Management, which controls the use of copyrighted digital work. MPEG4 is used for web streaming media, broadcast television, videophones, and CD distribution. MPEG-4 is widely used in video surveillance, and has recently been improved to the AVC standard.
MTBF (Mean Time Between Failures)
MTBF measures the average time that a device works properly without failure; unfortunately, it’s usually measured in hours. An hour measurement does not translate well to the average consumer looking for life expectancy in years.
MTTR
Mean Time To Repair - The average time it takes to fully repair a piece of equipment.
Multicast (or Multicasting)
This term refers to the Internet protocol that allows a single IP address (the host) to send a packet to multiple destinations at once with a single, local transmit operation. It also is used in video streaming to enable the broadcasting of video to multiple recipients at once.
Multimode
An optical fiber that supports more than one propagation mode.
Multiplexer
A device that can accept a number of camera inputs and almost simultaneously display them on a single monitor and/or record them. Multiplexers can also be used to transmit multiple cameras over the same transmission medium.
MUX
Multiplexer unit.
N
ND
Filter a filter that attenuates light evenly over the visible light spectrum. It reduces the light entering a lens, thus forcing the iris to open to its maximum.
Network Camera
Also known as a Network IP Camera, this is a stand-alone camera that uses a standard web-browser to view live, full motion video from a computer network, including over the Internet. They often feature an embedded OS (operating system) and features like: FTP of images, web server capability, and built-in motion detection.
Network Operation i
s a feature of many DVR digital video recorders. This allows the user to connect the DVR system to another computer or computer network for dynamic recording control and playback on other computers. Network operation is also interconnected with remote viewing capability for record and playback features over the internet. However, most network operation features are complex and not intended for most novice users. Connecting a DVR recorder to a PC network may require additional hardware such as a WAN or LAN router in addition to some prior networking knowledge and experience.
Noise
The word "noise" originated in audio practice and refers to random spurts of electrical energy or interference. In some cases, it will produce a "salt-and-pepper" pattern over the televised picture. Heavy noise is sometimes referred to as "snow".
Non-Composite Video
A video signal containing all information except sync.
Non-drop frame time code
SMPTE time code format that continuously counts a full 30 frames per second. Because NTSC video does not operate at exactly 30 frames per second, non-dropframe time code will count 108 more frames in one hour than actually occur in the NTSC video in one hour. The result is incorrect synchronization of time code with clock time. Drop-frame time code solves this problem by skipping or dropping 2 frame numbers per minute, except at the tens of the minute count.
Noninterlaced
The process of scanning whereby every line in the picture is scanned during the vertical sweep.
NTSC
Abbreviation for National Television Systems Committee. A committee that worked with the FCC in formulating standards for the present day United States color television system.
NVR (Network Video Recorder)
Functionally similar to a DVR, a NVR also accepts IP camera inputs. NVRs can be software based, making themsuitable only for accepting IP camera streams over the Internet.
Numerical aperture
A number that defines the light gathering ability of a specific fiber. The numerical aperture is equal to the sine of the maximum acceptance angle.
O
O/P
Output.
Objective
The very first optical element at the front of a lens. Ocular. The very last optical element at the back of a lens (the one closer to the CCD chip).
Ohms
These are units that measure the impedance or resistance of an electrical device.
Omni-Directional Antenna
An antenna for wireless equipment which sends or receives a propugated radio signal in all directions simultaneously. This differs greatly from a directional antenna which is only capable of sending or receiving information on the same axis as the corresponding antenna on the other end. Omni-directional antennas are great for short range broadcasts because of their versatility. However, high gain directional antennas are recommended for most long range wireless video applications.
Operating System (or OS)
indicates the basic computer platform a DVR video recorder operates with. Because of their stability and reliability,ALL feature embedded operating systems like Linux. DVRs with these operating systems are considered much more stable and reliable for obtaining important video evidence than competing Windows®-based DVR systems.
Operating Temperature
indicates the temperature at which a device can safely and effpixelsly work.
Optical Filters
These filters selectively allow for different frequency light to pass through.
Oscilloscope
This troubleshooting device translates electrical signals into voltage versus time based waveforms that are displayed onscreen, allowing visual feedback when adjusting CCTV components.
Overscan
A video monitor condition in which the raster extends slightly beyond the physical edges of the CRT screen, cutting off the outer edges of the picture.
Outdoor Camera
Outdoor cameras come in special weatherproof housings that allow them to stand up well in tough weather and temperature conditions.
Outdoor Camera Housing
A protective shell for security cameras to be placed in outdoor environmental conditions, these housings typically include cooling fans for summer use and heaters for winter use. The heaters also eliminate fogging of the glass anytime this occurs.
Outdoor Dome Housing
This housing is dome shaped for insertion of dome security cameras, is very tamper resistant, and allows for PTZ.
Output
The signal level at the output of an amplifier or other device.
Output impedance
The impedance a device presents to its load. The impedance measured at the output terminals of a transducer with the load disconnected and all impressed driving forcestaken as zero.
Output Voltage
indicates the type of electrical current (AC or DC) and the voltage a device will emit to safely and effpixelsly power another device
P
PAL (Phase Alternating Line) /CCIR
The video standards used throughout Europe. CCIR is the monochrome standard. PAL is the color standard which adds on top of the CCIR. The USA similar standards are NTSC and EIA. The European and American standards do not work together.
Pan
refers to horizontal (side to side) dynamic motion of a camera. Any equipment capable of panning can rotate back and forth along a horizontal axis. Some equipment, indicated as "PTZ," has the ability to pan as well as tilt and zoom.
Pan and Tilt
A device upon which a camera can be mounted that allows movement in both the azimuth (pan) and in the vertical plane (tilt).
Pan/Tilt Preset Positioning
Follower pots are installed on pan/tilt unit to allow feedback to the controller and provides information relevant to horizontal and vertical positioning, allowing the controller to quickly adjust to a pre-selected scene automatically.
Pan-Tilt-Zoom (PTZ) Cameras
PTZ cameras allow you to adjust the position ('pan' is side-to-side, 'tilt' is up-and-down) and focus ('zoom') of the camera using a remote controller. Due to this added functionality, these cameras tend to cost much more than non- PTZ cameras
Pan unit.
A motorized unit permitting horizontal positioning of a camera.
Passive
If a system component is non-powered, it is considered passive.
Patch Panel
A panel where circuits are terminated and facilities provided for interconnecting between circuits by means of jacks and plugs.
Parabolic Dish Antenna
An antenna for wireless equipment in the shape of a round concave dish or grid panel (similar to a home satellite dish). As highly directional antennas, parabolic dishes send or receive a propugated radio signal on the same axis as the corresponding antenna on the other end (with line-of-sight visibility between the two whenever possible). While omni-directional antennas are great for short range broadcasts because of their versatility, high gain directional antennas are recommended for most long range wireless video applications.
PCM
Pulse Coded Modulation
PCMCIA Card (Personal Computer Memory Card International Association)
These storage devices resemble a credit card and are typically used to expand the hardware functionality of portable devices such as laptops. In video surveillance application, PCMCIA cards can be used with portable PCs to add realtime full motion video capture of live security video. When used with digital cameras, they provide portable storage and a method for saving and transferring photos between digital cameras and PCs.
Peak Pulse Amplitude
The maximum absolute peak value of a pulse, excluding those portions considered to be unwanted, such as spikes.
Peak-to-Peak
The amplitude (voltage) difference between the most positive and the most negative excursions (peaks) of anelectrical signal. A full video signal measures one volt peak to peak.
Peak White Inverter
Circuitry that will convert white highlights over a pre-set threshold to black, useful for car registration recognition with headlights.
Pedestal.
In the video waveform, the signal level corresponding to black. Also called setup.
Pelco-D
This Pelco created protocol is used to control PTZ security camera movement.
Pentaplex or Pentaplex DVR
A pentaplex DVR is a DVR that can perform all the DVR functions at the same time: record, view/playback, network (view remotely), administrate and backup. For example, a machine that is not pentaplex would stop recording while the administration functions were being performed. Compare to a duplex DVR or a triplex DVR.
Phot.
A photometric light unit for very strong illumination levels. One phot is equal to 10,000 luxes
Photo Detector
A device fitted to fiber optic link to convert light into electrical signals.
Photocell
A device used to detect changes in light level to provide automatic operation of lights etc.
Photon
A photon is the basic unit of light.
Photo-effect.
Also known as photoelectric-effect. This refers to a phenomenon of ejection of electrons from a metal whose surface is exposed to light.
Photopic vision.
The range of light intensities, from 105 lux down to nearly 10–2 lux, detectable by the human eye
Photo multiplier.
A highly light-sensitive device. Advantages are its fast response, good signalto-noise ratio and wide dynamic range. Disadvantages are fragility (vacuum tube), high voltage and sensitivity to interferenc.
Picture Element
See Pixel
Pigtail
Short length of fiber optic cable attached to another component such as a source or coupler.
Pin-Hole Camera
Pin-hole cameras have a very small lens that can see through a small hole. These types of cameras are used in covert applications. A disadvantage of pin-hole cameras is that they require more lighting than normal cameras to capture a good clear picture
Pinhole lens. - A fixed focal length lens, for viewing through a very small aperture, used in discrete surveillance situations. The lens normally has no focusing control but offers a choice of iris functions. Phase locked loop (PLL). A circuit containing an oscillator whose output phase or frequency locks onto and tracks the phase or frequency of a reference input signal. To produce the locked condition, the circuit detects any phase difference between the two signals and generates a correction voltage that is applied to the oscillator to adjust its phase or frequency.
PIP
Picture In Picture - device used to superimpose one video image over another.
PIR
Passive Infrared. A motion detector that senses body heat to detect motion.
Pixel
Short for Picture Element. A pixel is the smallest area of a television picture capable of being delineated by an electrical signal passed through the system of part thereof. The number of picture elements (pixels) in a complete picture, and their geometric characteristics of vertical height and horzontal width, provide information on the total amount of detail which the raster can display and on the sharpness of the detail, respectively.
Plug and Play Cable
A cable that makes wiring cameras easy. Each camera needs to have a power wire and video wire (and sometimes an audio wire too), plus the connectors at the end of the wire to plug it in. The plug and play cables have all three wires built into one cable with the connectors already attached. The only disadvantage of plug and play cable is that the signal tends to degrade if run distances. For DVRs - plug and play cables can be run reliably up to 100 ft. For analog systems - plug and play cable can be run up to 400 ft. If you need to run longer distances then you need to use the RG59 or RG6 Siamese cable.
Plumbicon.
Thermionic vacuum tube developed by Philips, using a lead oxide photoconductive layer. It represented the ultimate imaging device until the introduction of CCD chips. Polarizing filter. An optical filter that transmits light in only one direction (perpendicular to the light path), out of 360° possible. The effect is such that it can eliminate some unwanted bright areas or reflections, such as when looking through a glass window. In photography, polarizing filters are used very often to darken a blue sky.
PoE
Power Over Ethernet - an adaptor that allows you to transmit power to a security camera through CAT5 (aka Ethernet) cable.
Post-record
This is a DVR's ability to record after a motion detection event has occurred. It records for a specified amount of time after the event has been triggered, even though the motion may have ceased.
POTS.
Plain old telephone service. The telephone service in common use throughout the world today. Also known as PSTN.
P-picture.
Prediction-coded picture. An MPEG term to describe a picture that is coded using motion-compensated prediction from the past reference picture.
Potentiometer
This device measures voltage or a potential voltage difference by comparing it with a standard voltage. It can also change resistance by moving the contact point, and is used to record pre-set positions in both zoom lenses and pan tilt heads.
Power Supply
See: AC Adaptor - All CCTV devices require power of some sort. Electricity in the United States comes in one form, 110 to 120 AC. The AC adaptor converts the AC power to DC power and will adjust it to a specified amperage. Power supplies should come included with each item.
Power Input
Plug indicates the proper size and proper polarity configuration for a device's input voltage.
Power Output
Plug indicates the proper size and proper polarity configuration for a device's output voltage.
Power Zoom
indicates the ability to adjust a camera's field of view by remote control. Power zoom may also be described as remote zoom.
PPP (Point-to-Point Protocol)
Point-to-point Protocol is the primary method used in establishing a direct connection between two devices on a network (usually a computer and the Internet). It is a communication protocol between computers using one of several methods: usually TCP/IP, telephone lines, or ISDN.
PPPoE
Point-to-Point Protocol over Ethernet. Presets The pre-positioning of pan, tilt and zoom cameras by the use of potentiometers in the moving parts of the camera head. These allow the control equipment to store and move to a set reference point when the controller dictates or when an alarm exists.
Pre-record
Pre-record is a setting on DVR systems that applies to motion recording. Normally, when a DVR is set to record motion, it takes a second to begin recording once the motion has been triggered. With pre-record selected, a buffer of the previous 140 frames before motion was triggered is recorded to the drive, allowing the security camera to capture one or two seconds prior.
Pre-set controller
A function contained within a telemetry system that, on receipt of a signal, causes a particular camera to pan, tilt, and zoom to a predetermined field of view. Most systems can accommodate up to sixteen preset positions for each camera. This is an especially useful feature on larger systems with alarmed areas.
Preset positioning.
A function of a pan and tilt unit, including the zoom lens, where a number of certain viewing positions can be stored in the system’s memory (usually this is in the PTZ site driver) and recalled when required, either upon an alarm trigger, programmed or manual recall.
Principal point.
One of the two points that each lens has along the optical axis. The principal point closer to the imaging device (CCD chip in our case) is used as a reference point when measuring the focal length of a lens.
Pressure mat
Placed before doorways, gates, and other entrances, this device responds to pressure (usually being walked or stood upon) to either open doors or activate the surveillance camera trained on that area.
Primary Colors
Three colors wherein no mixture of any two can produce the third. In color television these are the additive primary colors red, blue and green.
Progressive Scan
The progressive scan format outputs data from the camera (the signal) in sequential order as it is scanned. The scan format produces a full frame of video in a continuous stream, rather than half the image per output sequence in traditional RS-170 CCD cameras. Standard RS-170 video is interlaced and output in two separate fields, generating essentially half the image at a time. With Cohu's new 6600 Series Progressive Scan Camera, a new, full image is output from the camera every 1/60th second, making it ideal for machines to more quickly process and display information, or act according to programmed instructions.
Protocol
Protocols are standard procedures used for regulating data transmission between computers. Protocols exist to minimize errors during the exchange of data.
PROM.
Programmable read only memory. A ROM that can be programmed by the equipment manufacturer (rather than the PROM manufacturer).
PSTN
Public Switched Telephone Network - analogue communications network used for day to day telephone and data transmission.
PTZ
Pan-Tilt-Zoom - PTZ cameras allow you to adjust the position ('pan' is side-to-side, 'tilt' is up-and-down) and focus ('zoom') of the camera using a remote controller. Due to this added functionality, these cameras tend to cost much more than non-PTZ cameras
PTZ camera.
Pan, tilt and zoom camera
PTZ controller
The controller used to control PTZ camera movement, usually software or a joystick.
Pulse.
A current or voltage that changes abruptly from one value to another and back to the original value in a finite length of time. Used to describe one particular variation in a series of wave motions.
Q
QAM. - Quadrature amplitude modulation.
Method for modulating two carriers. The carriers can be analog or digital.
QCIF
This resolution is one quarter of CIF, with 144 lines and 176 pixels per line.
Quad
An analog device used to display 4 cameras simultaneously on a single monitor.
Quad compressor (also split screen unit).
Equipment that simultaneously displays parts or more than one image on a single monitor. It usually refers to four quadrants display.
Quad Processor
is a video switching device that accepts video input from four cameras and converts them to all display on one monitor and / or video recorder. When using multiple cameras, quads and multiplexers help to cut down on the amount of additional equipment needed for a dedicated surveillance system. However, DVR digital video recorders with multiple video inputs are quickly replacing quads and multiplexers. DVRs are now capable of doing what required a processor and VCR in the past (plus a whole lot more).
Quality Differences there are literally hundreds of different cameras available in the CCTV industry which on the outside appear very similar or identical to those offered at Eyespyvideo.com. However, inside these cameras (the crucial part) are so many different image sensors, each with different levels of performance, that it becomes quite confusing to even the experienced camera shopper. Beyond inspecting technical specifications and even the advertised CCD manufacturer, it is also important to test for actual real world performance. We thoroughly examine each part we stock (as well as many others which do not make the cut) to ensure their high tvres and performance under a variety of conditions. Eyespyvideo.com is proud to carry only the finest quality CCTV surveillance equipment available on the market today.
R
Radio frequency (RF).
A term used to describe incoming radio signals to a receiver or outgoing signals from a radio transmitter (above 150 Hz). Even though they are not properly radio signals, TV signals are included in this category.
Rack Mount
Piece of equipment that can be housed into a rack enclosure, industry standard is 19inches with the height measured in ‘U’ - 1U = 1.75
RAM.
Random access memory. Electronic chips, usually known as memory, holding digital information while there is power applied to it. Its capacity is measured in kilobytes. This is the computer’s work area.
RAID.
Redundant arrays of independent disks. This a technology of connecting a number of hard drives into one mass storage device, which can be used, among other things, for digital recording of video images
Random interlace.
In a camera that has a free-running horizontal sync as opposed to a 2:1 interlace type that has the sync locked and therefore has both fields in a frame interlocked together accurately
Range finder
This is a device that determines the required focal length and the resulting monitor image. While looking through it, the user can adjust the range finder to get the optimal image, with numbers on the range finder displaying the needed focal length.
Raster
A raster is a rectangular scan pattern of lines that the picture is created upon. It also refers to an active TV monitor that has no video information displayed.
RCA
An electrical connector invented by Radio Corporation of America, from which its name is derived. Consists of 3 wires - red, yellow, and white, these are commonly used on a wide assortment of products in the audio/video market.
Real Media
Real Networks developed an early multimedia protocol for video and audio (often streaming) called Real Media.
Realtime (or real time) refers to video recorded at the same speed as action occurs (so it may be played back at the speed of real time without drag). Realtime video is phased at 30 frames per second (60 fields per second) for NTSC video and 25 frames per second (50 fields per second) for PAL format equipment. Basically all VCR recorders record realtime video, but MOST digital DVR recorders do not. DVR systems capable of both displaying AND recording realtime video for seamless recording of important action.
Real-Time Recording
In digital video applications, 30 frames per second per camera (see above) looks just like real-time. There is no hesitation or jerkiness in the video.
Receiver
can refer to two different devices for CCTV. Wired receivers are used to demodulate video for extended video runs of more than one hundred and fifty feet. These receivers convert a video signal (and potentially a power and / or audio signal) from an RF radio frequency signal into composite video for TV display and recording. A transmitter at the opposite end of the wiring first modulates that signal into the RF frequency before sending it to the receiver for decryption. Wireless receivers similarly demodulate video (and sometimes audio) from an RF radio frequency, but this signal is "beamed" from a transmitter through the air without wires. A wireless transmitter sends it video images back to this wireless receiver. 900 MHz, 2.4 GHz, and 5.8 GHz wireless transmitters broadcast to matching paired receivers tuned to the same frequencies. 434 MHz transmitters are made to broadcast to any "cable ready" television or home VCR on channel 59 of the CATV band (i.e. a standard television or VCR with built-in tuner serves as the wireless receiver). Because wireless equipment can be quirky (just like cell phone or TV reception), high quality and professional wireless receivers are recommended. The wireless receivers all use FM modulation (more consistent and reliable than AM) and high gain standard antennas to help ensure fewer breakups in crucial video than substandard wireless link systems.
Receiver Sensitivity
indicates the sensitivity of a wireless receiver in picking up a good reliable signal from the matching wireless transmitter using the stock antenna. Sensitivity measurements of -75 dB and lower indicate very high gain potential for a wireless receiver.
Recording Media
refers to the magnetic storage device used to store recorded video. For many analog recorders this is a tape cassette, but DVR recorders use HDD hard disk drives. CDs and DVDs can also be types of media used to record digital video.
Recording tvres
refers to the maximum number of horizontal lines of tvres a VCR or DVR video recorder is capable of recording. Most consumer recorders do not detect nearly the number of lines of horizontal TV tvres high quality CCD cameras produce. However, using a high quality, high tvres video recorder can yield brilliantly sharp images on playback. VCR and DVR video recorders have been selected for the highest tvres recording available for CCTV equipment.
Reed switch
This type of alarm activating device becomes active when contact is either opened or closed, as in a door or window being opened or closed. They are also capable of switcher activation to activate the relevant security camera.
Reflectance
Ratio to which is reflected of a given surface, normally shown as a percentage.
Reflected Light
Scene illumination multiplied by reflectance, this is the light level available for the camera and determines picture quality.
Regenerators
Units placed at regular intervals along a transmission system to detect weak signals and regenerate them.
Registration.
An adjustment associated with color sets and projection TV’s to ensure that the electron beams of the three primary colors of the phosphor screen are hitting the proper color dots/stripes.
Regulated power supply
A DC power supply with a minimal ripple factor is considered to be regulated.
Relay
An electrically controlled device that opens and closes electrical contacts to effect the operation of other devices in the same or another electrical circuit.
Remote Control
is a device used to control the features of a piece of equipment without physically adjusting anything on the equipment. Some products feature a wired remote control. This allows a user to control many functions remotely, but this controller must be plugged directly into the device. Other products can be used with a wireless remote control. These types of controllers allow the user to adjust functions remotely. The information is "beamed" wirelessly to the device using an IR infrared signal from the controller.
Remote Playback
is a feature of many DVR video recorders. This allows users to play back recorded video over the internet from virtually any computer in the world.
Remote head surveillance camera
For surveillance situations where space is limited, this type of camera separates the CCD chip from the camera body by cable, considerably shrinking the overall camera size.
Remote monitoring
This allows an off site user to monitor surveillance camera feeds, so a user can survey a site regardless of their location from it. The transfer of data from camera to user can be either over the Internet or the Ethernet, with IP cameras being suited to the task.
Remote switcher
A video switcher which is connected to the camera cables and which contains the switching electronics. This unit may be remotely located and connected to a desktop controller by a single cable for each monitor.
Remote Surveillance
The ability to view your cameras from a remote location. Information is transmitted via phone line or internet.
Remote Viewing
is a feature of many DVR video recorders. This allows users to monitor CCTV cameras over the internet from virtually any computer in the world.
Remote Zoom
indicates the ability to adjust a camera's field of view by remote control. Remote zoom may also be described as powered zoom.
Repeater
A device that amplifies and then re-transmits a signal.
Resolution
Refers to how much detail can be captured on a camera or displayed on a monitor. Cameras typically capture about 380 horizontal lines of resolution. High resolution cameras may capture 450 lines of resolution or more. The higher the resolution, the more detail that can be captured in a picture. The monitors and recording devices can generally handle at least as much resolution as the cameras can capture.
Resolution (horizontal)
The amount of resolvable detail in the horizontal direction in a picture. It is usually expressed as the number of distinct vertical lines, alternately black and white, which can be seen in a distance equal to picture height.
Resolution, Limiting
The details that can be distinguished on the television screen. Vertical resolution refers to the number of horizontal black and white lines that can be resolved in the picture height. Horizontal resolution refers to the black and white lines resolved in a dimension equal to the vertical height and may be limited by the video amplifier bandwidth.
Resolution (vertical)
The amount of resolvable detail in the vertical direction in a picture. It is usually expressed as the number of distinct horizontal lines, alternately black and white, which can theoretically be seen in a picture.
Retained Image
Also called image burn. A change produced in or on the target which remains for a large number of frames after the removal of a previously stationary light image and which yields a spurious electrical signal corresponding to that light image.
Retrace.
The return of the electron beam in a CRT to the starting point after scanning. During retrace, the beam is typically turned off. All of the sync information is placed in this invisible portion of the video signal. May refer to retrace after each horizontal line or after each vertical scan (field).
Remote control.
A transmitting and receiving of signals for controlling remote devices such as pan and tilt units, lens functions, wash and wipe control and similar.
RETMA.
Former name of the EIA association. Some older video test charts carry the name RETMA Chart.
RF (Radio Frequency)
A frequency at which coherent electromagnetic radiation of energy is useful for communication purposes. Also, the entire range of such frequencies.
RF Input Plug
indicates the connection interface between pieces of wireless equipment. In most cases, the RF input plug refers to the appropriate plug type for connecting an antenna to a wireless transmitter or receiver.
RF Output Plug
indicates the connection interface between pieces of wireless equipment. In most cases, the RF output plug refers to the type of plug coming from a wireless antenna for connecting into the RF antenna input plug on a wireless transmitter or receiver.
RF Output Power
indicates the effpixels "strength" of a wireless transmitter's audio / video signal. Generally speaking, RF output power (in combination with RF frequency) has a huge effect on the range one can expect from a wireless transmitter. Transmitters with higher output power (operating on the same frequency) will in most cases deliver a longer distance wireless broadcast range. All wireless link transmitters have been selected to feature high RF output power for consistent long-range wireless performance. RF output power is typically measured in milliwatts (mW) or watts (W).
RF signal.
Radio frequency signal that belongs to the region up to 300 GHz.
RG-11
Having a thick center core, this type of coaxial cable is used to transmit video signals of up to 550m.
RG-59
More commonly used than RG-11 for CCTV, this coaxial cable transmits video signals of up to 230m.
RGB (Red Green Blue)
These are the three primary colors of light. All other colors are derived from their mixture.
RG59 Siamese Cable
This type of cable combines the power wire with the video wire. You have to add your own connectors to each end of the cable. Use this type of cable when you need to run distances longer than 100 ft with a digital system, or more than 400 ft. with an analog system.
Ripple
Amplitude variations in the output voltage of a power supply caused by insufficient filtering.
Rise Time
The time required for the leading edge of a pulse to rise from 10% to 90% of its total amplitude.
RMS.
Root Mean Square. A measure of effective (as opposed to peak) voltage of an AC waveform. For a sine wave it is 0.707 times the peak voltage. For any periodic waveform, it is the square root of the average of the squares of the values through one cycle.
ROI (Region of Interest)
Applied to the field of video surveillance, ROI stands for Region of Interest, meaning an area of the frame where motion is detected, in turn activating the surveillance camera.
Roll
A loss of vertical synchronization which causes the picture to move up or down on a receiver or monitor.
ROM.
Read only memory. An electronic chip, containing digital information that does not disappear when power is turned off.
Routing Switcher.
An electronic device that routes a user-supplied signal (audio, video, etc.) from any input to any user-selected output. This is a broadcast term for matrix switchers, as we know them in CCTV.
Router
A router is a piece of equipment facilitating the exchange of packets throughout LAN or WAN networks. It moves packets across a predetermined path to their destination by storing and forwarding the packets, and then determining their optimal path along the network. A router is hardware based, but can also include software.
RS-125.
A SMPTE parallel component digital video standard. practices for NTSC color television signals in the United States.
RS170
Video Sync Pattern for the United States - 525 lines @ 60Hz.
RS232 (or RS-232)
This is the communication standard that applies to PC serial communications. RS232 is commonly used as the mechanism for sending instructions that control PTZ security camera movement.
RS422
Communications network
RS485
Communications network
RTP (Real-time Transport Protocol)
The Internet Engineering Task Force (IETF) developed RTPs to specify audio and video signal management. It standardizes the packet formatting for both for easy synchronization and Internet delivery. Streaming media systems and video conferencing systems use RTP, while DVR systems rely on this protocol in the implementation of the remote view feature. Since it doesn’t specify how video surveillance playback is implemented, the data from different RTP based surveillance systems usually cannot interoperate.
RTSP (Real Time Streaming Protocol)
This open standard for Internet streaming of audio and video is popular among DVR makers for remote viewing of live or stored security camera video over the Internet. RTSP controls the transmission of the data stream much the way a television remote controls the television. Like RTP, interoperability problems exist between different DVR systems.
S
SAD (Sum of Absolute Difference)
This acronym refers to a mathematical technique used in motion detection.
Saturation
In color, the degree to which a color is diluted with white light or is pure. The vividness of a color, described by such terms as bright, deep, pastel, pale, etc. Saturation is directly related to the amplitude of the chrominance signal.
Scanning
The process of moving the electron beam of a pickup tube or a picture tube across the target or screen area of a tube.
Scanning System refers to the method in which video information is processed for display on a monitor is an interlaced system in which each frame of video is scanned in two fields on a horizontal line. This type of system is called 2:1 interlace video.
Scanner.
- When referring to a CCTV device it is the pan only head.
- When referring to an imaging device it is the device with CCD chip that scans documents and images
Scene illumination
The density of light in LUX falling on the area to be viewed. For best results, the ratio of the lightest to the darkest areas should not be more than a factor of two.
Scotopic vision.
Illumination levels below 10–2 lux, thus invisible to the human eye.
SCSI. -
Small computer systems interface. A computer standard that defines the software and hardware methods of connecting more external devices to a computer bus.
Sensitivity
In television, a factor expressing the incident illumination upon a specified scene required to produce a specified picture signal at the output terminals of a television camera.
SECAM.
Sequential Couleur Avec Memoire, sequential color with memory. A color television system with 625 lines per frame (used to be 819) and 50 fields per second developed by France and the former U.S.S.R. Color difference information is transmitted sequentially on alternate lines as an FM signal.
Sensitivity
in television, a factor expressing the incident illumination upon a specified scene required to produce a specified picture signal at the output terminals of a television camera.
Serial data.
Time-sequential transmission of data along a single wire. In CCTV, the most common method of communicating between keyboards and the matrix switcher and also controlling PTZ cameras.
Serial interface.
A digital communications interface in which data are transmitted and received sequentially along a single wire or pair of wires. Common serial interface standards are RS-232 and RS-422.
Serial port.
A computer I/O (input/output) port through which the computer communicates with the external world. The standard serial port is RS-232 based and allows bidirectional communication on a relatively simple wire connection as data flow serially. Sidebands. The frequency bands on both sides of a carrier within which the energy produced by the process of modulation is carried.
Server
A computer program that provides services to other computer programs in the same or other computers. Or, the computer that a server program runs
Sequential Switcher
Video Switcher. A device that allows the video signals from multiple cameras to be displayed on a monitor, or recorded on a VCR one at a time in sequence.
Shield
A covering put between cables to prevent interference caused by signal leakage.
Shutter
Ability to control the integration (of light) time to the sensor to less than 1/60 second; e.g: stop motion of moving traffic.
Shutter speed
This is the speed which the CCD chip can read out the charge. Using either dipswitches or a surveillance camera’s menu (if one has been built in), the default setting of 1/50 sec (PAL) or 1/60 sec (NTSC) can be increased up to 1/100,000.
Simplex, Duplex, and Triplex
concern the operation of video recorders and multiple camera video processors like quads and multiplexers. Simplex, duplex, or triplex capability reveals the number of device capacities which can be used simultaneously. For instance, a simplex device is only capable of performing one type of task at a time, whether that be recording or playback. A duplex device can perform two simultaneous functions like record and configure the monitor display for a certain close-up view. Triplex devices are capable of three tasks at the same time (usually record, playback, and zoom or other display functions).
Signal-to-Noise Ratio
The ratio between useful television signal and disturbing noise or snow. This number represents how much signal noise the camera can tolerate and still provide a good picture. The higher the number the better.
Signal System
refers to the basic electrical system frequency a video image is phased on. In the United States and many other places across the world, 60 Hz is the standard for most all types of AC and DC electrical devices (including video cameras and monitors). For this reason, standard NTSC video is phased at a frequency of 60 Hz. PAL format video, on the other hand, has a signal phased at a rate of 50 Hz
Silicon.
The material of which modern semiconductor devices are made.
Simplex
A type of multiplexer that allows you to simultaneously record images to tape and display the live, full screen image of any individual security camera (compare this to the duplex type which can also display multiple-picture screen images while recording). A simplex multiplexer can display multiple-picture screen images, but it cannot record at the same time. Also unlike a duplex multiplexer, it is unable to record and playback recorded tapes simultaneously.
SIT
Silicon Intensified Target - a CCD camera used in very low light conditions.
Single-mode fiber.
An optical glass fiber that consists of a core of very small diameter. A typical single-mode fiber used in CCTV has a 9 mm core and a 125 mm outer diameter. Single-mode fiber has less attenuation and therefore transmits signals at longer distances (up to 70 km). Such fibers are normally used only with laser sources because of their very small acceptance cone.
Skin effect.
The tendency of alternating current to travel only on the surface of a conductor as its frequency increases.
Slow scan.
The transmission of a series of frozen images by means of analog or digital signals over limited bandwidth media, usually telephone.
Smear.
An unwanted side effect of vertical charge transfer in a CCD chip. It shows vertical bright stripes in places of the image where there are very bright areas. In better cameras smear is minimized to almost undetectable levels.
SMPTE.
Society of Motion Picture and Television Engineers.
SMPTE time code.
In video editing, time code that conforms to SMPTE standards. It consists of an 8-digit number specifying hours: minutes: seconds: frames. Each number identifies one frame on a videotape. SMPTE time code may be of either the drop-frame or non-drop-frame type.
SMS (Short Message Service)
Some of the more advanced Network cameras feature software that sends notifications via the Cellular network to authorized users after programmed events. Griffid is one example of SMS being implemented in network surveillance software.
SMTP (Simple Mail Transfer Protocol)
This is the standard server-to-server protocol for the delivery of electronic mail, either via Internet or on other TCP/IP networks.
Smart Search
This is a feature of our digital video recorders that allows you to search for changes in a particular area of an image over time. For example, if a wallet was stolen off of a table, you could go to a point on the video where the wallet is there, draw a virtual box around that area, then search the video recording for changes to that particular area. This would allow you to locate the exact point on the video where the wallet was removed.
Snow
Heavy random noise.
Spectral Response
Sensitivity of an image device to different frequencies of light, visible light is 300 to 730nm IR (infra-red) is 715 - 850nm.
Spectrum.
In electromagnetics, spectrum refers to the description of a signal’s amplitude versus its frequency components. In optics, spectrum refers to the light frequencies composing the white light which can be seen as rainbow colors.
Spectrum analyzer.
An electronic device that can show the spectrum of an electric signal.
SPG.
Sync pulse generator. A source of synchronization pulses.
Split-screen unit (quad compressor).
Equipment that simultaneously displays parts or more than one image on a single monitor. It usually refers to four quadrants’ display.
Spot Filter
a small filter placed in the center of one of the elements of a lens to increase the ability of a camera to pass light. These filters are "neutral density" type which do not affect the colour rendition of the lens.
Staircase (in television).
Same as color bars. A pattern generated by the TV generator, consisting of equal width luminance steps of 0, +20, +40, +60, +80, and +100 IRE units and a constant amplitude chroma signal at color burst phase. Chroma amplitude is selectable at 20 IRE units (low stairs) or 40 IRE units (high stairs). The staircase pattern is useful for checking linearity of luminance and chroma gain, differential gain and differential phase.
Speed Of Update
The time taken to refresh a single picture.
Spike
A transient of short duration, comprising part of a pulse, during which the amplitude considerably exceeds the average amplitude of the pulse.
Spot Cam
Spot Cams are effective security cameras, useful for general surveillance needs. They are intended to be operable out of the box (mounting bracket often not included), and most have their own integrated varifocal lens. Be certain to choose a Spot Cam with its own auto iris feature and day/night capability.
Spot filter
A supplement to the iris which allows very sensitive cameras to view bright scenes easily. The iris of a lens without a spot filter would not be able to close down enough in bright light without creating image degradation.
Standard Minimum Signal
1000 microvolts at 75 ohms (0dB mV) in RF systems; 0.7-VPP non-composite, 1-VPP composite in video systems.
Start bit.
A bit preceding the group of bits representing a character used to signal the arrival of the character in asynchronous transmission.
Static IP address
This is an IP address that doesn’t change. Any computer can connect to it, thereby making video surveillance systems with static IP addresses remotely accessible from any location on the Internet.
Strike
A plate mortised into or mounted on the door jamb to accept and restrain bolt when the door is closed. In some metal installations of deadlock, the strike may simply be an opening into the jamb. (Synonym: keeper)
Storage Temperature
indicates the highest and lowest possible temperature at which a device can safely and effpixelsly be stored or shipped.
S-Video
Representing an improvement in quality over composite video, S-Video separates chrominance and luminance onto two different signal wires, resulting in better picture quality.
SVHS
(Super Video Home System): Super VHS; a higher quality extension of the VHS home videotape format. Switcher Sequential Switcher or Video Switcher A device that allows the video signals from multiple cameras to be displayed on a monitor, or recorded on a VCR one at a time in sequence.
S/N (Signal-to-Noise)
Ratio indicates the ratio of noise to actual total signal (in a video or audio signal generally speaking). The S/N number measures how much higher the signal level is to the level of background electronic noise, so a higher number means a clearer and crisper picture. Signal-to-noise ratio is expressed in decibels (dB).
Square Board Camera
A square board design refers to a camera with a square shape using a board-style video imaging chip (rather than an inline bullet design). These cameras are usually called "board cameras," though they may have either an exposed board or an enclosed board.
Sub-carrier (SC).
Also known as SC: 3.58 MHz for NTSC, 4.43 MHz for PAL. These are the basic signals in all NTSC and PAL sync signals. It is a continuous sine wave, usually generated and distributed at 2V in amplitude, and having a frequency of 3.579545 MHz (NTSC) and 4.43361875 MHz (PAL). Sub-carrier is usually divided down from a primary crystal running at 14.318180 MHz, for example, in NTSC, and that divided by 4 is 3.579545. Similar with PAL. All other synchronizing signals are directly divided down from sub-carrier.
S-VHS.
Super VHS format in video recording. A newer standard proposed by JVC, preserving the downwards compatibility with the VHS format. It offers much better horizontal resolution up to 400 TV lines. This is mainly due to the color separation techniques, high-quality video heads and better tapes. S-VHS is usually associated with Y/C separated signals.
Switch
A switch will take multiple camera inputs and will show them on the monitor one at a time. Unlike a quad it will not display them all at once, instead it sequences through them showing one camera at a time. It will also allow you to select a particular camera to view.
Switcher
A device that routes video and or audio signals to different sources.
Sync
A contraction of "synchronous" or "synchronize".
Sync Generator
A device for generating a synchronizing signal.
Sync Level
The level of the peaks of the synchronizing signal.
Sync Signal
The signal employed for the synchronizing of scanning.
Synchronizing
Maintaining two or more scanning processes in phase.
T
T1
A digital transmission link with a capacity of 1.544 Mbps. T1 uses two pairs of normal twisted wires. T1 lines are used for connecting networks across remote distances. Bridges and routers are used to connect LANs overT1 networks.
T1 channels.
In North America, a digital transmission channel carrying data at a rate of 1.544 million bits per second. In Europe, a digital transmission channel carrying data at a rate of 2.048 million bits per second. AT&T term for a digital carrier facility used to transmit a DS-1 formatted digital signal at 1.544 Mbps.
T3 channels.
In North America, a digital channel that communicates at 45.304 Mbps commonly referred to by its service designation of DS-3.
TA
Terminal Adaptor - used to connect video transmission products to an ISDN digital telephone line.
TBC (Time Base Corrector)
Multiplexers and quad splitters rely on a TBC circuit to align unsynchronized video signal before the signal processing begins.
TCP/IP (Transmission Control Protocol/Internet Protocol)
These protocols enable communication between differing computer and computer networks. The IP is a connectionless protocol that provides the packet routing, while the TCP is connection based to provide reliability in communication and multiplexing.
TDG
Time & Date Generator - device used to superimpose the time and date onto a video image.
Tearing
A term used to describe a picture condition in which groups of horizontal lines are displaced in an irregular manner.
Teleconferencing.
Electronically linked meeting conducted among groups in separate geographic locations.
Telemetry
The system by which a signal is transmitted to a remote location in order to control CCTV equipment, eg. to control pan, tilt, and zoom functions, switch on lights, move to preset positions, etc. The controller at the operating position is the transmitter and there is a receiver at the remote location. The signal can be transmitted along a simple twisted pair cable, or along the same coaxial cable that carries the video signal.
Telephoto lens
In order to make distant objects appear larger, cameras require a telephoto lens.
Television Lines (TVL)
This is a measure of the resolution of a video device. Higher number is higher resolution. 380 TVL is considered medium resolution. 480 TVL or greater is considered high resolution.
Termination
This refers to a 75 Ohm terminator that is used to terminate each end of a video line.
Test Pattern
A chart especially prepared for checking overall performance of a television system. It contains various combinations of lines and geometric shapes. The camera is focused on the chart, and the pattern is viewed at the monitor for fidelity.
TFT.
Thin-film-transistor. - This technology is used mainly for manufacturing flat computer and video screens that are superior to the classic LCD screens. Color quality, fast response time and resolution are excellent for video.
Tilt
refers to vertical motion of a camera. Any equipment capable of tilting can move up and down along a vertical axis. Some equipment, indicated as "PTZ," has the ability to tilt as well as pan and zoom.
Time / Date Generator
Installed between a CCTV camera and a monitor, it generates the information of Date, Time and camera ID.
Time Base Correction
Method used to align unsynchronized camera signals, widely used by multiplexers and quad splitters.
Time lapse VCR (TL VCR)
A video recorder, most often in VHS format, that can prolong the video recording on a single tape up to 960 hours (this refers to a 180 min tape). This type of VCR is often used in CCTV systems. The principle of operation is very simple – instead of having the video tape travel at a constant speed of 2.275 cm/s (which is the case with the domestic models of VHS VCRs), it moves with discrete steps that can be controlled. Time Lapse VCRs have a number of other special functions very useful in CCTV, such as external alarm trigger, time and date superimposed on the video signal, alarm search and so on.
Time lapse video recording.
The intermittent recording of video signals at intervals to extend the recording time of the recording medium. It is usually measured in reference to a 3-hr (180-min) tape.
Time multiplexing.
The technique of recording several cameras onto one time lapse VCR by sequentially sending camera pictures with a timed interval delay to match the time lapse mode selected on the recorder
Total Pixels
concerns the operation of a camera's CCD image sensor. This number measures the complete count of pixel elements on a camera's CCD image sensor. This number should not be confused with effpixels pixels, which can provide a more telling description of a camera's tvres.
Touch Screen Control
A system by which all the camera controls are displayed on the screen of a special monitor. To control any function simply requires the screen to be touched at the appropriate symbol which can select a camera or pan, tilt, and zoom. The system is computer driven and can include maps, diagrams, etc. that are automatically displayed according to the alarm received.
TP
Twisted Pair - an electrical conductor that consists of two insulated conductors twisted around each other.
T-pulse to bar.
A term relating to frequency response of video equipment. A video signal containing equal amplitude T-pulse and bar portions is passed through the equipment and the relative amplitudes of the T-pulse and bar are measured at the output. A loss of response is indicated when one portion of the signal is lower in amplitude than the other.
Tracking
A zoom lens that can stay in focus while zooming from wide angle to telephoto position is said to be tracking.
Transcoder.
A device that converts one form of encoded video to another, e.g., to convert NTSC video to PAL. Sometimes mistakenly used to mean translator.
Transducer
Device used to convert energy into an electrical signal.
Transformer
A device used to transfer electric energy from one circuit to another, especially a pair of multiply wound, inductively coupled wire coils that affect such a transfer with a change in voltage, current, phase, or other electric characteristic.
Transients
Signals which exist for a brief period of time prior to the attainment of a steady-state condition. These may include overshoots, damped sinusoidal waves, etc.
Translator.
A device used to convert one component set to another, e.g., to convert Y, R-Y, B-y signals to RGB signals.
Transmitter
can refer to two different devices for CCTV. Wired transmitters (sometimes called modulators) are used to modulate video for extended video runs of more than one hundred and fifty feet. These transmitters convert a video signal (and potentially a power and / or audio signal) into an RF radio frequency signal. A receiver at the opposite end of the wiring demodulates that signal back into traditional composite video for compatibility with standard equipment. Wireless transmitters similarly modulate video (and sometimes audio) into an RF radio frequency, but this signal is "beamed" through the air without wires. A wireless transmitter sends it video images back to a wireless receiver. Eyespyvideo.com 900 MHz, 2.4 GHz, and 5.8 GHz wireless transmitters broadcast to matching paired receivers tuned to the same frequencies. 434 MHz transmitters are made to broadcast to any "cable ready" television or home VCR on channel 59 of the CATV band. Because wireless equipment can be quirky (just like cell phone or TV reception), high quality and professional wireless transmitters are recommended. The wireless transmitters ALL use FM modulation (more consistent and reliable than AM), high gain standard antennas, and very high RF output power to help ensure fewer breakups in crucial video than substandard wireless link systems.
Transponder. -
the electronics of a satellite that receives an uplinked signal from the earth, amplifies it, converts it to a different frequency and returns it to the earth.
Triplex or Triplex DVR
A triplex DVR is a DVR that can record, view/playback, and network (view remotely) at the same time. Keep in mind that manufacturers may use this term differently so check for details on the product. Compare to a duplex DVR or a pentaplex DVR.
TTL. 1. Transistor-transistor logic.
A term used in digital electronics mainly to describe the ability of a device or circuit to be connected directly to the input or output of digital equipment. Such compatibility eliminates the need for interfacing circuitry. TTL signals are usually limited to two states, low and high, and are thus much more limited than analog signals. 2. Thru-the-lens viewing or color measuring.
TVL
Television Lines - used to describe the resolution of a camera or monitor (460TVL).
Tvres
(Scanning lines) refers to something quite a bit different than what is generally considered to be tvres. Video display on a monitor requires the image to be constantly shifting (scanning) in order to display in real time. For instance, NTSC format video is based on a 525 scanning lines operating at a frequency of 60 Hz (PAL format is 625 lines, 50 Hz) for transmission and display of video images. This is an interlaced system in which each frame is scanned in two fields of 262 lines, which is then combined to display a complete frame of video with 525 scan lines. Scan lines (also referred to as "vertical tvres") of video are equivalent for each different video format, but every device must comply with these standards. Horizontal tvres, on the other hand, indicates the number of pixel elements contained placed horizontally across these scanning lines. Horizontal tvres varies based on the abilities of each different camera and each different monitor.
Twisted Pair
A cable composed of two small, insulated conductors twisted together. Since both wires have nearly equal exposure to any interference, unwanted noise is substantially reduced.
TX
Transmitting equipment
U
UDP (User Datagram Protocol)
UDP is a communications protocol that makes possible the sending of datagram messages from one computer to an application in another computer. It’s connectionless and suffers from unreliability, since it is unable to check for any errors in delivery. UDP is often a protocol used in video streaming because it ignores lost data and continues the live feed of information (this being preferable to the interruption of real-time data while attempting to retransmit lost data).
UHF signal.
Ultra high frequency signal. In television it is defined to belong in the radio spectrum between 470 MHz and 850 MHz.
Unbalanced Signal
Term used for coaxial cable transmission. In CCTV, this refers to a type of video signal transmission through a coaxial cable. It is called unbalanced because the signal travels through the center core only, while the cable shield is used for equating the two voltage potentials between the coaxial cable ends
Underscan.
Decreases raster size H and V so that all four edges of the picture are visible on the monitor.
UPS (Uninterruptible Power Supply)
Justifiably popular with many electronics users, a UPS stores electricity in a battery and supplies power to a system (allowing a user to shut down w/out losing data or continue for a specific time period) during a power failure.
Unterminated
Input of a piece of CCTV system that requires to lopped to another piece of equipment for 75ohm termination.
URL (Uniform Resource Locator)
The URL is the Internet address that a software browser requires in order to find that Internet resource.
UTP (Unshielded Twisted Pair)
This type of cable is used to transmit video signals across distances greater than a coaxial cable can handle. The RG59 standard of UTP cable is roughly 600 ft. In conjunction with video baluns, they can stretch over 1200 ft. for full color video. UDP is cost effective too, mainly due to lower costs than coaxial cable, being easily terminated, and being capable to carrying data, video, and audio signals across the same cable with little interference
V
Variable bit rate.
Operation where the bit rate varies with time during the decoding of a compressed bit stream.
Varifocal Lens
A camera lens in which the focus is not fixed, it can be manually or automatically adjusted.
VDA.
See video distribution amplifier.
Vectorscope
An instrument similar to an oscilloscope, that is used to check and/or align amplitude and phase of the three color signals (RGB).
Velocity of propagation.
Speed of signal transmission. In free space, electromagnetic waves travel at the speed of light. In coaxial cables, this speed is reduced by the dielectric material. Commonly expressed as percentage of the speed in free space.
Vertical interval
The portion of the video signal that occurs between the end of one field and the beginning of the next. During this time, the electron beams in the monitors are turned off (invisible) so that they can return from the bottom of the screen to the top to begin another scan.
Vertical interval switcher
A sequential or matrix switcher that switches from one camera to another exactly in the vertical interval, thus producing roll-free switching. This is possible only if the various camera sources are synchronized.
Vertical Resolution
The number of horizontal lines that can be seen in the reproduced image of a television pattern
Vertical retrace.
The return of the electron beam to the top of a television picture tube screen or a camera pickup device target at the completion of the field scan.
Vertical shift register.
The mechanism in CCD technology whereby charge is read out from the photosensors of an interline transfer or frame interline transfer sensor.
Vertical sync pulse
A portion of the vertical blanking interval which is made up of blanking level. Synchronizes vertical scan of television receiver to composite video signal. Starts each frame at same vertical position.
Vestigial sideband transmission
A system of transmission wherein the sideband on one side of the carrier is transmitted only in part.
VGA.
Video graphics array
Vibration sensor
A device that activates when it detects vibrations in its detection zone, and then activates a specific surveillance camera is known as a vibration sensor.
VHF
Very high frequency. A signal encompassing frequencies between 30 and 300 MHz. In television, VHF band I uses frequencies between 45 MHz and 67 MHz, and between 180 MHz and 215 MHz for Band III. Band II is reserved for FM radio from 88 MHz to 108 MHz.
VHS.
Video home system. As proposed by JVC, a video recording format used most often in homes but also in CCTV. Its limitations include the speed of recording, the magnetic tapes used and the color separation technique. Most of the CCTV equipment today supersedes VHS resolution.
Video Amplifier
A wideband amplifier used for passing picture signals.
Video Band
The frequency band width utilized to transmit a composite video signal.
Video bandwidth.
The highest signal frequency that a specific video signal can reach. The higher the video bandwidth, the better the quality of the picture. A video recorder that can produce a very broad video bandwidth generates a very detailed, high quality picture on the screen. Video bandwidths used in studio work vary between 3 and 12 MHz.
Video Capture Card - DVR card
Computer cards that you can install on the motherboard of a computer to create your own video recording computer .
Video compression
This technique (often a MPEG format) compresses video into lower bit rates for easier Internet transmission, often along narrower bandwidths. Video or audio is compressed to shrink file size, ensuring acceptable transfer speed. Compressed video can sometimes be of a noticeably lower quality, but still clear enough to be useful. AVC is the successor to MPEG as the new video compression standard.
Video Gain
An increase in video signal power by an amplifier, expressed as the ratio of output to input. Also called amplification.
Video equalization corrector (video equalizer)
A device that corrects for unequal frequency losses and/or phase errors in the transmission of a video signal.
Video framestore.
A device that enables digital storage of one or more images for steady display on a video monitor.
Video in-line amplifier
A device providing amplification of a video signal.
Video Input
A connection in a video controller or recording device that you can plug a camera into. The more video inputs (also called camera inputs) available on a device the more cameras you can connect to it.
Video Input Type
refers to the type of video a device will accept for display, recording, etc. Our equipment (just like the majority of consumer video equipment most clients have at home) is made for compatibility with composite video. For use with S-Video, RGB component video, VGA, or other specialized / digital video formats, an adapter or converter may be required.
Video Input Plug
indicates the plug size and configuration used for a device's video input. The most common types of plugs for composite video are BNC, RCA, and 1/8" mini.
Video intercom
Used at door entryways, this system utilizes audio and video for communication or movement control of people.
Video Launch Amplifier
An amplifier placed between the video source and the transmission cable, used where the signal needs to be processed before being launched over coaxial or twisted pair cables.
Video matrix switcher (VMS)
A device for switching more than one camera, VCR, video printer and similar to more than one monitor, VCR, video printer and similar. Much more complex and more powerful than video switchers.
Video monitor
A device for converting a video signal into an image.
Video Motion Detection
A system that detects motion in the video signal and generates a corresponding alarm. This can be accomplished by some cameras, multiplexers and digital recorders. This feature maximizes recording space by only recording while motion is detected.
Video Output Type
refers to the type of video a camera or other device will output for display, recording, etc. on another device. Our equipment (just like the majority of consumer video equipment most clients have at home) is made for compatibility with composite video. For use with S-Video, RGB component video, VGA, or other specialized / digital video formats, an adapter or converter may be required.
Video Output Plug
indicates the plug size and configuration used for a device's video output. The most common types of plugs for composite video are BNC, RCA, and 1/8" mini.
Video printer.
A device for converting a video signal to a hard copy printout. It could be a monochrome (B/W) or color. They come in different format sizes. Special paper is needed.
Video Quality
is of course always subjective. However, when most users describe high quality video they are referring to a sharp and clear video image without distortion. Because of the high quality components and superior manufacturing of products found on Atss, these video devices feature amazing video quality. Consumers need to be aware that there are many quality differences available in the CCTV video surveillance industry.
Video server
This enables an analog camera to be converted into an IP camera, able to stream digital video over an office network, phone, or ISDN connection. Therefore, an analog based surveillance system can be upgraded and networked to function as an IP surveillance system.
Video Signal (Non-Composite)
The picture signal. A signal containing visual information and horizontal and vertical blanking (see also Composite Video Signal) but not sync.
Video streaming
Streaming video delivers compressed multimedia content over the Internet in a stream of packets. Viewers view the file as it downloads, instead of downloading the entire file first. Streaming video first initializes the transfer, and then buffers it. Bandwidth determines both picture quality and whether or not the viewed video catches up with the downloading content, which causes the video to stop. RealPlayer is one of the most popular free streaming video players available. Video streaming is commonly used for viewing live feeds from security cameras, with RTSP/RTP being the main streaming technology currently in use.
Video surveillance
This term refers to the use of CCTV and DVR to monitor secure sites, or portions thereof. Video Surveillance systems can start with a few as one camera. For systems using more than 16 cameras, enterprise video surveillance systems are preferable. The many terms defined in this glossary give an idea of the many options available for different security needs and situations. In today’s professional world, Video Surveillance (often referred to as CCTV) is the most cost effective way to achieve loss prevention.
Video switcher.
device for switching more than one camera to one or more monitors manually, automatically or upon receipt of an alarm condition.
VITS
Video insertion test signals. Specially shaped electronic signals inserted in the invisible lines (in the case of PAL, lines 17, 18, 330 and 331) that determine the quality of reception.
Video wall
A video wall is a large screen made up of several monitors placed close to one another, so when viewed from a distance, they form a large video screen or wall.
VLF.
Very low frequency. Refers to the frequencies in the band between 10 and 30 kHz.
VMD
Video motion detector. A detection device generating an alarm condition in response to a change in the video signal, usually motion, but it can also be change in light. Very practical in CCTV as the VMD analyzes exactly what the camera sees, i.e., there are no blind spots.
VOD.
Video on Demand. A service that allows users to view whatever program they want whenever they want it with VCR-like control capability such as pause, fast forward and rewind.
Voltage Drop
Voltage loss experienced by electric circuits due to two principal factors: (1) wire size and (2) length of wire runs.
Volt/Amp (VA) Rating
The product of rated input voltage multiplied by the rated current. This establishes the "apparent energy" available to accomplish work.
- - Virtual Reality. Computer-generated images and audio that are experienced through hightech display and sensor systems and whose imagery is under the control of a viewer.
- VS. - Vertical sync.
W
WAN (Wide Area Network)
A WAN is a communications network serving a geographically large area using satellite communications or telephone lines. The Internet is a WAN. Network IP Cameras are capable of utilizing WAN systems.
Watch Dog Timer Circuit Protection
If problems are detected in the DVR computer the system will automatically reboot to correct the problem.
Waterproof
A device that can be immersed in water and still function properly.
Watt
A common unit of electrical power. A watt is dissipated by a resistance of one ohm through which one ampere flows.
Watch-dog timer
The automatic reboot of a DVR system whenever a problem is detected.
Wavelength
Wavelength is how far an electro magnetic wave travels during one cycle. When discussing DVR, the term refers to the color of light, which every color having a different wavelength.
Wavelet
This type of image compression is mainly used for single images and not video streams. Because it’s superior to JPEG compression, it is however used in some video surveillance codecs, though there isn’t a universally adopted standard for usage of this codec.
Waveform monitor
Oscilloscope used to display the video waveform.
WAN
Wide Area Network.
WDM (Wavelength Division Multiplexing)
This economical procedure enables data from different sources to be simultaneously transmitted over the same fiber optic link. It achieves this by assigning a unique wavelength to each data channel, resulting in many possible wavelengths traveling across one link, which allows one fiber link to do the same work as two or more.
Weatherproof
A device that is weatherproof can be installed outside and stand up to harsh weather conditions and temperatures. However, it does not mean that it is waterproof.
Webcam
Webcams are cameras that connect to the Internet, either via PC or directly, and that allow remote user access. An IP camera is a popular webcam for video surveillance that does not need a PC connection.
White balance
CCD security cameras feature this adjustment to compensate for ambient light color. Since there’s a color difference between standard light bulb light and sunlight, white balance adjusts to ensure a more realistic picture. This feature may be set by manual adjustment, or it may have preset settings for the most common situations.
Wide angle lens
This lens enables a wide view of the scene, with a magnification ratio less than 1.
Wireless
The wireless transmission of video signals can be carried out over both short and long ranges, with 2.4 to 5 GHz devices for short distances and high-power line dedicated site solutions for several miles or more.
Wireless Operation refers
to "beaming" a video and / or audio signal through the air without wires from a transmitter element to a receiver element. However, wireless equipment DOES still have some wires. All electronic devices need a connection to a power source (input voltage) to function. At the same time, plugs and wires are also necessary to attach a wireless transmitter to a camera or microphone. There will also be wires required to plug the wireless receiver into a monitor or recording device.
Wireless Camera
Wireless cameras allow the transmission of video and audio data to be transmitted to the receiver without having to run wires (using radio waves).
White Balance
A process used in video cameras to retain true colors.
White level
The brightest part of a video signal corresponding to approximately 1.0 volt.
Wow and flutter
Wow refers to low frequency variations in pitch while flutter refers to highfrequency variations in pitch caused by variations in the tape-to-head speed of a tape machine.
W-VHS
A new wide-VHS standard proposed by JVC, featuring a high resolution format and an aspect ratio of 16:9.
X
No entries for this letter
Y
Yagi Antenna
An antenna for wireless with a series of antenna elements placed along a metal rod. As a highly directional antenna, yagi antennas are intended to send or receive a propugated radio signal on the same axis as the corresponding antenna on the other end (with line-of-sight visibility between the two whenever possible). While omni-directional antennas are great for short range broadcasts because of their versatility, high gain directional antennas are recommended for most long range wireless video applications
Y/C
A video format found in Super-VHS video recorders. Luminance is marked with Y and is produced separate to the C, which stands for chrominance. Thus, an S-VHS output Y/C requires two coaxial cables for a perfect output.
Y, R-Y, B-Y.
The general set of component video signals used in the PAL system as well as for some encoder and most decoder applications in NTSC systems; Y is the luminance signal, R-Y is the first color difference signal and B-Y is the second color difference signal.
Y, U, V.
Luminance and color difference components for PAL systems; Y, B-Y, R-Y with new names; the derivation from RGB is identical.
Z
Z
In electronics and television this is usually a code for impedance.
Zoom
refers to an adjustable field of view. Cameras may have manual zoom with a Varifocal lens or remote zoom with a powered zoom lens. Some DVR video recorders also have the ability to change the monitoring field of view and zoom in or out on selected areas of a recorded video image.
Zoom ratio
A mathematical expression of the two extremes of focal length available on a particular zoom lens.
Zoom Lens
An optical system of continuously variable focal length, the focal plane remaining in a fixed position.
Zero
Lux Operation refers to video imaging in pitch black (0.0 lux) lighting conditions. Monochrome CCD cameras can use IR Infrared lighting to yield crisp and distinguishable video images when absolutely no visible light is available.
#
20 mA Current Loop:
A data communications format that can be used for long distance network communications over dedicated “hard copper” telephone lines. Logic states are represented by current flow and the absence of current flow.
25 VRMS Audio:
Audio distribution that uses a constant 25 VRMS signal and a multi-tap transformer at each speaker to adjust individual speaker volume.
70 VRMS Audio:
Audio distribution that uses a constant 70 VRMS signal and a multi-tap transformer at each speaker to adjust individual speaker volume.
A
A-Weighted
A method of measuring sound loudness as perceived by the human ear.
ACAM
Access Control and Alarm Monitoring.
Access
A means to enter an area or obtain certain information.
Access Code
A combination of numbers and/or letters that identifies an individual to a system, for the purpose of authorizing entry or use by the individual.
Access Level
The privileges assigned to an individual specifying the levels of fire alarm control panel access.
Account
A subscription to a Central Monitoring Station’s services.
Acknowledgement
(1) Confirmation that a message has been received. (2) In telecommunications, a control signal that completes the handshaking sequence.
Activate
To turn on an output or function.
Active Sensor
A sensor that Is in the “on” state.
Activity Report
A record of events maintained by a central monitoring station of signals received from a protected premise.
Address
A number that provides a unique identifier for a specific device, module, or power supply. Address numbers may be in binary, hexadecimal, or decimal format
Addressable Device
A system component that is uniquely identifiable by the system.
Addressable Loop
An alarm system circuit that supports addressable alarm, supervisory, monitor, output, or relay devices.
Addressable System
A system that can individually identify a specific initiating and output devices.
Addressable Zone Module
An addressable device that acts as a transponder for one or more conventional alarm devices. Activation of any conventional device connected to the zone module results in the addressable device’s address being reported.
Agency Listings and Approvals
Standards to which the system equipment and operation conforms, as set by the applicable standards/approvals agency.
AHU
An Air Handling Unit.
Air Sampling-type Detector
A smoke detector that uses a suction fan and tubing to sample remote areas for products of combustion.
Alarm
The state of a system that generates a visible or audible warning signal when abnormal conditions exist in a machine, system, or environment. See Alarm Condition and Alarm Signal.
Alarm Circuit
An electrical path that produces or transmits alarm information.
Alarm Condition
(1) A threatening condition sensed by a detector. (2) The state of an alarm control indicator that has been activated.
Alarm Discrimination
The ability of an alarm system to distinguish between its normal surrounding environment and the stimuli of an actual alarm condition.
Alarm Dispatch
A notification sent to police, fire, or medical personnel, indicating an unauthorized intrusion or other emergency. Initiated by a person or alarm system in response to a stimulus.
Alarm Signal
An indication of an off-normal condition requiring immediate attention, e.g. a notification of fire.
Alarm Signal Cutoff
See Automatic Signal Silence Timer
Alarm Silence/Reset Inhibit
A control panel feature that automatically disables the system silence and reset functions for a predetermined period of time.
Alarm Threshold
The temperature, obscuration level, etc. above which an alarm is initiated by a particular sensor.
Alarm Verification
Technique used to reduce unwanted alarms in automatic fire detection and alarm systems. To be accepted as a valid alarm initiation signal, smoke detectors must report alarm conditions for a minimum time period or confirm alarm conditions within a given time after being reset. Also called Verified Alarm.
Alert Signal
Notification that advises occupants of a possible fire condition, but not requiring immediate evacuation.
All Call
Selection of all paging zones for the purpose of making a facility-wide page or notification.
All Clear
An audible signal used to communicate a “safe to return” condition to people already evacuated from a building.
Alphanumeric
Text consisting of both letters and numbers.
Alphanumeric Keypad
An operator interface component for entering text and numeric information into a system to control system functions, e.g. programming, shunting or arming/disarming the system.
Alternate Prealarm
The ability of an intelligent addressable device to change prealarm threshold levels. Typically used to automatically change detector sensitivity levels for day and night operation.
Alternate Sensitivity
The ability of an intelligent addressable device to change alarm threshold levels. Typically used to automatically change detector sensitivity levels for day and night operation.
American Wire Gauge (AWG)
The standard American designation of wire sizes. Wire size is an inverse relation to gauge numbers that range from 0000 to 40 AWG. Also called Brown and Sharpe or B&S gauge.
Americans with Disabilities Act (ADA)
A US Federal act to ensure that individuals with handicaps will be reasonably accommodated. Relevant sections of this Act detail the requirements for audible and visual notification appliances and mounting heights for manual pull stations.
Amplifier
An electronic component that increases signal level. Typically used to take increase signals from microphones and pre-recorded message units for reproduction by audio speakers.
Analog Initiating Device (Sensor)
An initiating device (sensor) that transmits continuous level of the value being sensed to a control panel. The control panel makes the alarm decision when the value reaches the minimum alarm level.
Analog Smoke Sensor
See Smoke Sensor (Analog)
Ancillary Device
A device connected to a fire alarm system not required by the fire alarm standard but may be required by other standards, e.g. door holders, smoke control fans, remote LED indicators, remote alarm, or trouble units.
Annunciator
A visual and/or audible system component that indicates an alarm or other condition. Annunciators are typically located at building entrances or at emergency control locations. May consist of LEDs, and/or LCDs and may take the form of a graphic representation of the building. Annunciators may also incorporate features such as system common controls.
ASCII
American Standard Code for Information Interchange. A standardized alphanumeric character computer code.
Audible
Able to be detected by the human ear.
Audible Notification Appliance
An indicating device that alerts an individual via the sense of hearing.
Audible Signal Circuit
See Notification Appliance Circuit
Audio System
A fire alarm system that uses voice or electronic tone transmissions to notify occupants of alarm events.
Audio System (Dual Channel)
An audio system capable of simultaneous signaling and paging.
Audio System (Single Channel)
An audio system capable of either signaling or paging, but not both at the same time.
Authority Having Jurisdiction
The government body, organization, office, or individual having the power to enforce and/or interpret laws, codes, and rules. Also responsible for approving equipment, installations or procedures (e.g.: Fire Marshall, building inspector).
Automatic Alarm
An alarm input activated by a device such as a smoke detector, heat detector, flame detector, or water-flow switch, without any manual operation.
Automatic Evacuation Timer
A control panel feature that enables evacuation signals after a preset time period if no action has been taken to inhibit the signals. The timer period of this feature may be individually set according to local jurisdiction, or disabled, as applicable.
Automatic Evacuation Timer Cancel
A control panel feature that cancels the automatic evacuation timer after being manually activated by the panel operator. Depending on jurisdiction, the automatic evacuation timer may restart should a new alarm occur after automatic evacuation has been canceled.
Automatic Fire Alarm system
A fire warning system that reacts to environmental changes (heat and smoke, etc.) without the need for human intervention.
Automatic Signal Silence Timer
A control panel feature that automatically turns off the notification appliances after a predetermined time period.
Auxiliary Fire Alarm System
A protected premise alarm system that transmits signals via the municipal fire alarm system to the public service answering point using the same equipment and in the same manner as alarms transmitted manually from street-side municipal fire alarm box.
Auxiliary Relay
An electrically operated switch contact that is activated by control panel programming to perform functions such as shutting down fans, controlling dampers, closing doors, recalling elevators, etc.
Average Ambient Sound Level
A weighted sound pressure level measured over a 24-hour period.
AWG
See American Wire Gauge
B
Back box
See Wallbox
Battery
A chemical-based secondary electrical source for the alarm system to ensure operability in the event of an AC power failure.
Battery Charger
An integral power supply element that maintains the backup batteries at a constant charge level when the system is powered by primary AC power.
Battery Time
The period of time that system batteries must fully power the system. Equals the specified supervisory time followed by the specified alarm time
Battery Time (Alarm)
The period of time that the batteries must power the system while it is in an alarm state in the event of a primary AC power failure.
Battery Time (Supervisory)
The period of time that the batteries must power the system while it is in the normal (supervisory) state in the event of a primary AC power failure.
Baud Rate
The measure of the speed of transmission of a digital signal.
Beam Detector
See Smoke Detector, Projected Beam.
Bell
An electro-mechanical resonant audible notification appliance.
Block Diagram
A drawing showing the major components of a system, their relative locations, and the relationship between components.
Bonding
The permanent joining of all non-current-carrying metal parts to assure electrical continuity with the capacity to safely conduct any likely current.
Bonding Conductor
A conductor connecting the non-current-carrying parts of the equipment or enclosures to the service equipment or system-grounding conductor.
Break
(1) To open an electrical circuit. (2) To destroy the integrity of an object.
Break-glass Station
A manual alarm pull station with a visible glass rod that is broken when the station is operated. The rod is designed to serve as a psychological barrier against false alarms.
Building Management System (BMS)
An integrated computer system for monitoring and controlling various aspects of a building’s operation such as heating, lighting, air conditioning, alarm systems, physical security, etc. Also called a Building Automation System (BAS).
Bus
A wire channel or path for transferring data and electrical signals, e.g. data bus, audio signal bus, signal bus.
C
CA31A or CA38A Jack
Canadian terminology. A modular connector used to connect telephone line devices (DACTs) to the telephone line. Known as RJ-31X in the U.S.
Cabinet
See Wallbox
Candela
The SI (metric) unit of measure for the luminous intensity of a light or strobe.
Central Alarm Control Facility (CACF)
The main command and control center for fire alarm and other monitoring functions (e.g. security, air handling), or the room from which an emergency situation is managed.
Central Monitoring Station (CMS)
A location that maintains a vigilant watch over a number of remote systems and takes appropriate action in response to system activity.
Change of State
The transformation of an input zone or device from the restored condition to active condition or from the active condition back to the restored condition.
Channel
A data or communications path.
Chime
A mechanical or electronic signaling device that produces a sound similar to a set of attuned bells.
City Tie Module (CTM)
A system component that provides a connection to either the local fire department or a central monitoring station. Also known as Fire Department Relay (FDR).
Class A
A wiring classification of circuits capable of transmitting an alarm signal during a single open or non-simultaneous ground fault on a conductor.
Class B
A wiring classification of circuits NOT capable of transmitting an alarm signal beyond a single open or during a short between conductors.
Coded
An audible or visible notification appliance that conveys discrete information. Coded notification information takes the form of the number of pulses of an audible appliance or number of flashes of a visible appliance.
Coded Signals
An alarm signaling method in which affected areas and types of alarms are identified by using different signaling sequences.
Coder
A system component that pulses coded signals in the prescribed code or sequence.
Combination Detector
A device that (1) employs more than one operating principle to sense a fire phenomenon (smoke, heat, flame, etc.) (2) responds to more than one indication of an intrusion attempt (glass breakage, vibration, or motion).
Command Port
A supervised network communications port that can receive and transmit network instructions to and from interactive subsystems, e.g.: color graphics or third party gateway computers.
Common Alarm
A control panel operating sequence where any active alarm input will cause all output circuits to activate.
Common Controls
The control panel feature switches and indicators that operate on a global or system wide basis, e.g.: signal silence, reset, acknowledge.
Common Relays
An electrically operated switch that operates whenever any one of a number of pre-defined events occurs, e.g. trouble relays, alarm relays.
Compatibility
The suitability of one device or system to be used in conjunction with another device or system.
Contact
(1) The mechanical parts of a switch/relay that make or break the electrical path. (2) A switch type sensor.
Contact Device
A sensor or component that opens/closes a switch or relay as its system interface.
Control Panel
The central unit of an alarm system which monitors the detection and input devices; then responds by activating signaling and other control devices in a prescribed manor.
Control Unit
A system component that provides the operational relationship between system inputs and system outputs and acts as the interface between the system and operator
Correlation
The relationship between input functions (alarm, supervisory, monitor, etc.) and output functions (signals, relays, etc.).
Correlation Group
A collection of input AND output devices. When any input in the correlation group activates, all output devices in the correlation group activate.
Customer Connect
Terminal strip to which external field wiring is connected.
D
Damper Control
The process of opening and/or closing heating and ventilating hardware (dampers), to isolate and exhaust smoke and to pressurize areas surrounding a fire.
Data Gathering Panel (DGP)
An addressable system interface that converts input signals to the format required by the addressable system and can convert commands from the addressable system controller into output contacts and signals.
Day/Night Switch
A device for toggling system status between daytime and nighttime modes.
DC-Blocking Capacitor
An electronic component wired in series with a device that allows the passage of an AC signal while blocking the DC supervisory current.
Deadfront
Panel construction that makes all live electrical parts inaccessible to unauthorized persons.
Detector
A system initiating device containing a sensor that responds to external stimulus such as heat, smoke, movement, vibration, etc.
Detector Coverage
(1) The recommended maximum distance between adjacent detectors. (2) The area, range & pattern that a detector is designated to protect.
Diagnosis
The identification and isolation of an equipment or system malfunction or failure.
Dialer
This system component that sends system status information over the public switched (dial-up) telephone network to a compatible receiver. See Digital Alarm Communicator Transmitter.
Digital Alarm Communicator Receiver (DACR)
A system component that accepts and displays signals from digital alarm communicator transmitters (DACTs) sent over the public switched telephone network.
Digital Alarm Communicator System (DACS)
A system that transmits signals from a digital alarm communicator transmitter (DACT) located on protected premises through the public switched telephone network to a digital alarm communicator receiver (DACR) at a monitoring location.
Digital Alarm Communicator Transmitter (DACT)
A system component at the protected premise that transmits system information to a DACR via the public switched telephone network.
Digital Alarm Radio Receiver (DARR)
A system component that receives and decodes radio signals, then displays the data.
Digital Alarm Radio System (DARS)
System components that transmit and receive system signals via a radio channel.
Digital Alarm Radio Transmitter (DART)
A DACT that provides an alternate radio transmission channel in addition to the public switched telephone network.
Digital Communicator
See Digital Alarm Communicator Transmitter, Digital Alarm Communicator Receiver, Digital Alarm Communicator System.
Digitized Message
A pre-recorded system audio message that is stored in computer memory chips.
DIP Switch
A group of two-position electrical contacts mounted in a Dual Inline Package (DIP), typically used to set address or function information.
Disable
A system command that intentionally places a device or system out of service, typically for maintenance.
Display
A system component that visually presents system information to the user.
Distributed Intelligence
The decentralization of system processing power and information between multiple locations/devices instead of concentrating power/information at a single location.
Door Holder
An electromagnetic device that retains a fire door in the open position and releases the door when directed by the fire alarm panel to control the spread of smoke.
Dual Tone Multi-Frequency (DTMF)
A method of representing numeric characters and symbols using two simultaneous voice-band tones. Also called Touch-Tone(R) dialing.
Duct Smoke Detector
A device that senses the visible and/or invisible products of combustion in an HVAC system.
E
EEPROM (E2PROM)
Electrically Erasable Programmable Read Only Memory. A non-volatile, reprogrammable memory chip.
Egress
Exit. See NFPA 101, chapter 5.
EIA (Electrical Industry of America) Rack Mounting
A standardized measurement unit system for mounting equipment in a cabinet in which 1 EIA Space = 1.75 inches. The standard rack mounting width is 19 inches.
Electrical Supervision
Monitoring the integrity of a circuit or device to detect a fault condition that would prevent normal operation.
Elevator Homing Alternate Floor
The floor to which an elevator will automatically be directed in the event of smoke detected in the elevator lobby of the primary elevator homing floor.
Elevator Homing Floor
The floor to which an elevator will automatically be directed in the event of smoke detected in an elevator lobby.
Emergency Lighting
An automatic illumination system that is activated whenever AC power fails in a building.
Emergency Power Supply
A secondary source of electrical power independent of the primary power supply, used to power critical systems in the event of an AC power failure.
Emergency Telephone System
A dedicated two-way voice communications network consisting of a master control panel and strategically located emergency telephone stations and/or phone jacks.
Emergency Voice Alarm Communications System
A dedicated one-way emergency audio communications system for originating and distributing voice instructions and signals to building occupants; may be manual, automatic, or both.
Enable
A command that allows an input device/circuit/zone to report its change of state or an output device/circuit/ zone to change state.
End-Of Line Device (EOL)
An electronic component physically installed as the furthest device from the control panel; whose presence on the circuit is used to monitor the integrity of the circuit.
End-of-Line Resistor
A resistive electrical component installed at the physical end of a device wiring loop to establish a supervision path to the control unit.
Environmental Compensation
The process used by a smoke detector to adjust its sensitivity baseline for the effects of as dirt, humidity, etc. that can generate false alarms.
Ethernet
Computer based networking technology used for local area networks (LANs).
Evacuation
The exiting of occupants from a building.
Evacuation Signal
Notification to occupants to leave the facility.
Event Log
A record of system operation and events with time, date, and other pertinent information.
Exhaust Fan
A component of an air handling or smoke control system that removes air from the area being serviced.
Expandability
The ability of a system or control panel to accommodate additional devices or remote panels.
Explosion proof
The ability of a device to contain an explosion within the device so as not to cause a vapor ignition or explosion in the atmosphere surrounding the device
F
FACP
Fire Alarm Control Panel
Fail Safe
A mode of operation that leaves a device in a harmless state in the event of a failure.
False Alarm
An unwarranted system event, typically caused by mischief, man-made disturbances, environmental conditions, equipment malfunction or unknown stimulus. Also called a nuisance alarm.
FCC (Fire Command Center)
A centralized operator control unit for displaying, monitoring, and controlling fire emergency situations with appropriate switches, indicators, common controls, graphic annunciators, and fan and damper controls.
FDR (Fire Department Relay)
See City Tie Module.
Fiber Optics
A thin glass thread that is used to achieve secure, noise-immune, wide band communications while providing immunity to cross-talk, lightning and power surges; and is suitable for use in explosive environments.
Field Panel
See Transponder
Field Programmable
The ability to customize control panel operation at the installation site.
Fire Alarm Control Panel (FACP)
An electronic unit that monitors fire detection devices and activates appropriate alarm notification appliances and other auxiliary appliances according to programmed instructions.
Fire Alarm Signal
An event initiated by a manual fire alarm box, automatic fire detector, water-flow switch or other device that indicates the presence of a fire or fire products.
Fire Alarm System
A specialized control system that monitors initiation devices that detect smoke and fire and provides appropriate notification, control, and system supervision functions.
Fire Command Center
A centralized operator control unit for displaying, monitoring, and controlling fire emergency situations with appropriate switches, indicators, common controls, graphic annunciators, and fan and damper controls.
Fire Detector
A device that detects a fire signature and automatically initiates an electrical signal to actuate an alert or alarm signal.
Fire Drill
The manual activation of fire alarm notification appliances in order to test evacuation procedures. The fire drill feature typically does not operate any programmed auxiliary functions or the central station connection.
Fire Fighters Elevator
A specially designated elevator, installed in its own separate shaft, suitable for use during a fire emergency.
Fire Fighters’ Telephone
A dedicated two-way emergency communications system provided as part of the fire alarm control system to facilitate communications between the fire command center and strategic outlying areas of the facility.
Fire Pump
A dedicated pump that provides additional water pressure for fire extinguishing systems (standpipe, sprinkler, hose lines).
Flame Detector
A device that senses the infrared, ultraviolet, and/or visible radiation produced by a fire to actuate an alarm signal.
Flow Switch
See Water-flow Alarm
Flush Mounting
Mounting equipment such that it has a minimum protrusion from the wall.
Form A Contact
A Normally Closed (N.C.) relay configuration
Form B Contact
A Normally Open (N.O.) relay configuration.
Form C Contact
A Single Pole Double Throw (SPDT) normally open/normally closed relay configuration.
Four-Wire Smoke Detector
A fire detection device that initiates an alarm (short) on one pair of wires and receives power over a second pair of wires.
Full Duplex
A communications path that allows simultaneous transmission of data in two directions
G
General Alarm (GA)
A facility-wide evacuation signal.
Giant Voice
A high power Mass Notification system typically installed as a wide-area solution to provide siren signal, pre-recorded, and live voice messages.
Graphic Annunciator
An system annunciator that features a scaled drawing of the facility and incorporating LEDs and switches for point annunciation and control of system features.
Ground Fault
An unwanted circuit path to earth ground.
Guard’s Tour Supervision
Monitoring of the sequence and timing of patrol stations activated by a guard on his rounds. Delayed activation or activation out of sequence initiates a supervisory alarm
H
Half Duplex
A communications path that allows transmission of data in two directions, but in only one direction at a time.
Hardwired System
A non-addressable alarm system that utilizes contact devices and circuit continuity to initiate an alarm condition and direct wired DC circuits to operate notification appliances. Also called a conventional system.
Harmonized Cordage
The European standard governing the construction, identification, and use of wire sizes and stranding.
Heat Detector, R-O-R Fixed Temperature
A heat sensitive switch that activates when the temperature of its operating element reaches a predetermined level or the rate of temperate rise (ROR) exceeds a preset limit.
Heat Detector, Fixed Temperature
A heat sensitive switch that activates when the temperature of its operating element reaches a predetermined level.
Heat Detector, Line
A linear heat activated switch that is sensitive along its path (as opposed to a spot detector), and activates when the temperature along its operating element reaches a predetermined level.
Heat Detector, Non-restorable
A heat sensitive switch with a sensing element that is destroyed in the process of detecting a fire.
Heat Detector, Rate Compensation
A fast acting fixed temperature sensor exhibiting low thermal lag.
Heat Detector, Rate-of-Rise
A heat sensitive switch that activates when the rate of temperate rise (ROR) exceeds a preset limit.
Heat Detector, Restorable
A heat sensitive switch with a sensing element that is not destroyed in the process of detecting a fire. Restoration may be automatic or require replacement of sensing elements.
Heat Detector, Self-Restoring
A heat sensitive switch with a sensing element that automatically returns to the non-alarm condition when its temperature is below the alarm threshold.
Heat Detector, Spot
A thermal detection device whose element senses temperature at a single point as opposed to along a path.
HVAC
Heating, Ventilating, and Air Conditioning. HVAC systems are governed under the provisions of NFPA 90A.
Hydraulic Motor Gong
A water-operated sprinkler bell that activates whenever water is flowing in the fire sprinkler system to alert passers-by to call the fire department.
I
Indicating Appliance Circuit (IAC)
See Notification Appliance Circuit (NAC)
Initiating Device
A manual device or automatic sensor that starts the processing of an event by a control system, i.e. manual fire alarm station or smoke detector.
Initiating Device Circuit (IDC)
A supervised input circuit that connects detectors, manual stations, etc. to the control panel.
Installation Drawing
A graphic representation of a system that details the methods, parts, locations, and other information for the proper installation, wiring, and testing of the system.
Integrated System
A combination of fire, security, access control, and CCTV functions in a seamless system that uses common hardware and facilitates interaction between these functional elements.
Intelligent Addressable Device
A individually identifiable input or output device incorporating a microprocessor and logic that is capable of making alarm/output decisions independent of a centralized host processor. Intelligent Addressable devices are occasionally polled by the control panel to verify communications and device status.
Interactive Device
An operator interface that delivers information to the operator and/or receives information from the operator, e.g. keypad, graphic annunciator, color graphics computer.
Interface
Hardware and/or software required to convert communications protocols between different equipment or systems
Interfaced System
A system consisting of two or more functional sub-systems that interact using hardware and/or software to convert communications protocols between the two sub-systems.
Intrinsically Safe
A category of devices that will not generate a spark or thermal effect during normal or fault condition that is capable of causing ignition of a specified gas, vapor, or dust.
IO
Input/Output
Ionization Smoke Detection
A sensing method using radioactive material to ionize the air between two electrodes; a sufficient number of smoke particles entering the ionized air space reduces ion mobility, and is processed as a smoke conditions.
IR
Infrared
K
Key Station
A key-operated initiating device used in institutions to prevent false fire alarms. Also used as a guard patrol station.
Keypad
A control unit interface used to input alphanumeric information.
L
Lamp Test
A control panel switch/feature that turns on all panel indicators to verify their operation.
Latching
An operating mode where a device’s state follows the state if the initiating stimulus.
LCD
Liquid Crystal Display
LED
Light Emitting Diode
Lexan®
A clear tough plastic material commonly used in alarm equipment doors/enclosures. Manufactured by GE Plastics.
Light Scattering
The process of using reflection and/or refraction of light off particles of combustion in a photoelectric smoke detector.
Line Seizure
The process used by a dialer (DACT) to gain and maintain access to a dial-up telephone line from other devices on the same phone circuit.
Line Supervision
The process of monitoring circuit security by sending a known signal over the circuit and measuring the signal/circuit for any change in characteristics that indicate tampering.
Listed
An indication that the equipment, material, or service meets the identified standards or has been tested and found suitable for the specified purpose and is included in a publication of a standards organization.
Local Alarm
An alarm system that limits notification to the protected premise only.
Log
A permanent record or history of system operation, listing each event, time of occurrence, etc.
Logic Functions
Boolean operators such as AND, OR, NOT, etc. that are used when programming control panels to achieve desired operation sequences.
M
Maintenance Alert
A system indication that an analog sensor has reached a level of contamination from dirt, etc. that requires routine maintenance.
Manual Fire Alarm Box
An occupant operated device used to initiate a fire alarm signal.
Manual Pull Station
An occupant operated device used to initiate a fire alarm signal.
March Time
An audible notification appliance rate equivalent to 90/120 strokes per minute to promote a fast walking cadence.
Mass Notification
The capability to provide real-time information and instructions to people, in a building, area, site, or installation using intelligible voice communications including visible signals, text, and graphics, and possibly including other tactile or other communication methods.
I/O (Input/Output) Matrix
A spreadsheet used to indicate the relationship of system inputs to outputs.
Modem
Abbreviation for MODulator-DEModulator. A communications device that converts data to audio tones in order to transmit/receive data via telephone lines.
Module
A functional system element packaged so that it can easily be added or removed from a system.
Monitoring
The process of maintaining a vigilant watch over a system or point and taking appropriate action in response to system activity.
Motherboard
The main circuit board into which daughter cards or modules are connected.
Multi-criteria Detection
An alarm initiating device that uses two or more sensing technologies to generate an alarm condition.
Multiplex
To interleave or simultaneously transmit two or more signals from remote devices over a single communications channel.
Multiplexing
A communications technique that can simultaneously process multiple signals over a single channel.
Multisensor Detection
See multi-criteria detection.
Multitasking
The ability of a computer to run two or more programs simultaneously. Example: Printing a report while simultaneously monitoring an alarm system.
Municipal Tie Module
See City Tie Module
N
National Fire Protection Association (NFPA)
An organization that is internationally recognized as a definitive authority on fire protection. The NFPA publishes and administers the development of codes, standards, and other materials concerning all aspects of fire safety for the United States.
Network
A group of interconnected functional elements that work together to create an overall functional group.
Node
The basic functional element of a network.
Non-Coded Signal
A constant output from a notification appliance.
Non-latching
An operating mode where a device’s state follows the state of the the initiating stimulus.
Non-restorable Initiating Device
A detection device with a sensing element that is not capable of re-use after sensing an alarm.
Normal Standby Condition
The quiescent state of a panel - not indicating any alarm, trouble, supervisory or off-normal status conditions.
Notification Appliance
A fire alarm system output device such as a horn, bell, strobe, speaker, or text display designed to gain the attention of occupants and signal appropriate action.
Notification Appliance Circuit
A supervised output circuit that connects horns, bells, strobe, speaker, etc. to the control panel.
Nuisance Alarm
See False Alarm.
O
Obscuration
The reduction in the atmospheric transparency caused by smoke or dust, expressed as a percentage.
On-Auto-Off Switch
A 3-position control panel switch used to set the manual (on or off) or automatic operation of a motor, fan, or other appliance.
Open Fault
An abnormal high circuit series resistance increase resulting in a trouble condition at the control panel.
Operating Mode, Private
Selected notification of only individuals directly involved with carrying out emergency procedures in an area protected by the fire alarm system.
Operating Mode, Public
Notification of occupants in an area protected by a fire alarm system, by audible or visible means.
Operating System Software
The fundamental system software that operates a microprocessor based system; sometimes referred to as “firmware’ or the “executive program.” Site-specific software is used by the operating system to customize system operation.
Optical Fiber
A thin glass thread that is used to achieve secure, noise-immune, wide band communications while providing immunity to cross-talk, lightning and power surges; and is suitable for use in explosive environments.
OS&Y Valve
Outside Screw and Yoke Valve typically used as a sprinkler shut-off valve. A tamper switch is used to indicate when the valve is closed.
Output
A signal generated to control external devices such as signals, relays, LEDs, control modules, etc.
P
Paging System
A non-supervised public address system for distributing voice messages to building occupants.
Paper Trail
Written documentation, including dates and times, etc. that verifies performance or completed work, tasks, tests, maintenance, etc. See Audit trail, Log.
Password
A sequence of alphanumeric characters associated with an individual to identify the person to a system.
Password Controlled System Access
A confidential system that permits operators and/or service personnel to operate various levels of protected features of a system. Used to prohibit unauthorized system operation or changes to the operation of the system.
Pattern
The shape of the coverage area/volume of a detection device.
Photoelectric Light Obscuration Smoke Detection
A sensing method that utilizes a light source that transmits its output directly to a light sensitive receiver. When smoke particles enter the light path, some of the light is scattered or absorbed, reducing the light at the receiver and processed as an alarm condition.
Photoelectric Smoke Detector
A sensing method that uses visible and/or infrared light to sense the presence of smoke particles. When smoke particles enter a light trap, light is reflected or refracted to a light sensitive component, which is processed as an alarm condition.
Plenum Area
A building compartment or chamber that forms part of the environmental air distribution system. Examples include the space above a suspended ceiling or under raised floors that carry environmentally conditioned air.
Plenum Cable
Specially insulated cable designed to limit fire and smoke spread for use in spaces that are also used to carry environmentally conditioned air.
Plenum Rated
Product construction that complies with code requirements for use spaces that are also used to carry environmentally conditioned air.
Point Contact Transmitter
A system transponder that is connected to a conventional contact device and capable of individually reporting the device’s status to the system.
Polarized Notification Device
A signaling appliance that incorporates a series diode such that the device operates only when the correct electrical polarity is provided. The series diode permits monitoring the integrity of the circuit Notification Appliance Circuit (on which the device is installed) using a small current of the “wrong” polarity through an end of line resistor.
Polling
The process of sequentially interrogating addressable devices to determine the device’s status.
Positive Alarm Sequence
Fire alarm operation that permits a short delay for investigation before generating an alarm signal.
Power Supply
The source of a system’s electrical operating power; usually a primary supply (AC mains) backed up by a secondary (DC Battery) supply.
Pre-Amp, Audio
Electronic circuitry that conditions and increases low level audio signals, to line level signals for distribution and use by audio distribution amplifiers.
Pre-Announce Tone
A signal or sound that precedes a voice message from a one-way emergency audio communications system, alerting occupants to pay attention to the message that follows.
Presignal System
A fire alarm that sends the first notification to a constantly attended location (maintenance/security office, switchboard, etc.) of an alarm event. A full alarm may be manually initiated, or is automatically initiated within 1 minute after the prealarm.
Pressure Alarm System
An alarm system that monitors an enclosed volume by increasing the air pressure in the protected volume, then monitoring the pressure differential between the protected volume and the environment outside the protected volume. Equalization of pressure due to compromising the structure will initiate an alarm signal.
Pressure Switch
As part of a dry sprinkler system, the pressure switch would cause water to charge the sprinkler piping if it detected a sudden drop in air pressure in the system caused by the opening of a closed sprinkler head.
Pressurization Fan
The component of a smoke control system that blows air into a smoke zone, thus increasing air pressue to minimize the entry of smoke into the zone.
Prioritized Reporting
A system function that sequences event annunciation such that life safety events (fire) are processed before lower priority events, i.e. security, trouble, etc.
Priority
The relative importance of system events.
Private Branch Exchange (PBX)
A private telephone switchboard.
Products of Combustion
The products that result from a fire such as heat, gases, and particles.
Projected Beam Smoke Detector
See Smoke Detector, Projected Beam
Proprietary Alarm System
An alarm system that serves one or more facilities under common ownership and is continuously monitored by trained personnel.
Protected premises
The facilities protected by an alarm system.
PSNI
Positive, Successive, Non-Interfering. A process used to sequentially output multiple event codes while preventing signals from clashing with each other.
Pull Station
See Manual Pull Station
Q
Quick Arm
A feature supported by some control panels which, if enabled, provides “short-cut” key presses for arming.
Quick Exit
A feature supported by some control panels which, if enabled, provides means for a single, short (several minutes) exit/reentry through a Delay Zone without requiring disarming an armed system.
R
Radio Frequency (RF)
Electromagnetic radiation, generally above 20 kHz.
RAM
Random Access Memory
Receiver
(1) Any device equipped for detecting electronically transmitted signals. (2) A device which monitors and displays signals from alarm systems.
Redundancy
(1) The availability of duplicate functional system elements such that should one element fail, the duplicate is available as to replace the failed element. (2) The availability of more than one method for performing a function. (3) The availability of multiple copies of data or equipment in the event of failure or damage.
Redundant Wiring Circuit (or Alternate Path Circuit)
A communications path having two or more independent routes between the same end points such that the failure of failure of one route switches the data to an alternate route, maintaining continuity of communications between the end points.
Releasing Device Service
The control of building safety systems by the fire alarm system. Examples of controlled systems include elevators; smoke control and venting systems, fire doors, and extinguishing systems.
Remote Alarm
Alarm signal that is sent to a remote monitoring station. May also activate a local alarm.
Remote Annunciator
See Annunciator
Remote LED Indicator
A device status indicator LED mounted separately from a device to indicate the device’s status. Typical applications are for smoke detectors located above false ceilings or below raised floors Remote Protective Signaling System: A fire alarm system that transmits alarm conditions to a remote manned location where appropriate action is taken.
Remote Receiving Equipment
Control panel and accessories for receipt of signals from fire alarm control panels located in distant buildings.
Remote Trouble Unit (RTU)
A panel fault annunciator that is located separately from the control panel.
Reset
A manually initiated alarm system function that returns the system and attached devices/systems back to normal operating condition.Response Time: The delay between the activation of an initiating device and the operation of an output device or function.
Restorable Initiating Device
A detection device with a sensing element that is operational after being reset.
Restore
Returning a device’s state back to normal.
Reverse Polarity
The process of providing normal/alarm indications on a DC circuit by swapping the (+) and (-) terminals. On some systems, trouble is indicated by an absence of any voltage.
Riser
An electrical path used to distribute power or signals.
Riser Diagram
A cross-section drawing that shows building levels, relative equipment locations and interconnecting system wiring.
RJ-31X Jack
A modular connector used to connect telephone line devices (DACTs) to the telephone line. Also known as CA31A or CA38A in Canada.
ROM
Read Only Memory
RS-232
A serial data communications format used for computer peripheral devices such as printers, modems, etc.
RS-485
A differential communications format used for networks and interconnecting control panels.
S
Satellite Station
An unattended location housing local receiving equipment. Signals are then sent from the satellite station to the remote receiving equipment station via high speed a communications channel.
Self-Diagnostics
The ability of a system to isolate and identify system faults.
Semi-Flush Mounting
Equipment installation where the equipment is partly recessed into a wall and partly protruding out from the wall.
Sensitivity
The alarm threshold of a sensing device.
Sensitivity Report
A list of sensors, current sensitivity values and in some reports, alarm threshold.
Sequence of Operation
A description of the series of events that will take place in response to the activation of a system input device.
Sequential Display
A visual output device that provides information on multiple events, one event at a time.
Short-circuit Fault
A low resistance between two conductors resulting from an abnormal condition.
Signal Circuit
See Notification Appliance Circuit
Signal Rate
The repetitive frequency/pattern at which a notification appliance operates.
Single Channel
A one-way emergency communication system capable of sounding one audio signal (live page, alarm message, alert message, etc.) at a time in response to an alarm condition.
Siren
An audible notification appliance characterized by a cyclical rising and falling output frequency.
Smoke Control System
A coordinated arrangement of supply, exhaust, and pressurization fans, dampers and monitoring devices, etc. configured to contain and/or evacuate smoke within a facility during a fire condition.
Smoke Detector
A device that senses the visible and/or invisible products of combustion.
Smoke Detector, Combination
A detector that employs more than one smoke detecting principle in one unit with each principle contributing in the response either entirely or partially.
Smoke Detector, Intelligent Addressable
An individually identifiable smoke detector that independantly makes the alarm decision; no communication with the control panel is required until after an alarm has been identified. Intelligent Addressable devices are occasionally polled by the control panel to verify communications and device status.
Smoke Detector, Ionization
A detector containing a small amount of radioactive material which ionizes the air in the sensing chamber, thus rendering it conductive and permitting a current flow between two charged electrodes in the sensing chamber. When products of combustion enter the chamber they decrease the conductance of the air by attaching themselves to the ions. When the conductance is less than the preset level, the detector activates.
Smoke Detector, Photoelectric
A detector containing a light source and a photosensitive sensor that are arranged so that the rays of the light source do not normally fall on the sensor. When smoke particles enter the light path, some of the light is scattered by reflection and refraction onto the sensor causing the detector to activate.
Smoke Detector, Projected Beam
A detector where light is transmitted and monitored between a source and a photosensitive receiver. When smoke particles are introduced in the light path, some of the light is scattered and some absorbed, thereby reducing the intensity of the light reaching the receiver causing the detector to activate.
Smoke Detector, Sampling
A detector that draws air samples through piping or tubing into the detector’s sampling ports. At the detector, the air sample is analyzed for products of combustion by ionization or photoelectric methods.
Smoke Detector (Analog)
A smoke sensitive sensor that continuously transmits (when polled) smoke obscuration values to the control panel. The panel evaluates the obscuration data against various alarm thresholds contained in its memory and responds accordingly.
Smoke Exhaust Fan
The component of a smoke control system that sucks air from a smoke zone in order to remove smoke and gases from the zone being protected.
Speaker Tap
A speaker output wattage adjustment on constant voltage (25 or 70 V) speakers having an integral transformer.
Spot Detector
An initiating device with a sensing element that is concentrated in a specific location.
Standby Amplifier
A backup audio amplifier installed to replace a faulty amplifier in order to maintain the operation of an audio emergency communication system.
Status
The state of a system or device. Examples; alarm, disabled, active, or off-normal.
Strobe Light
A visual notification appliance that produces a bright flashing high-intensity light using a Xenon flash tube.
Style
A classification system used to identify the performance of fire alarm Initiating Device Circuits (IDC), Notification Appliance Circuits (NAC), and Signal Line Circuits (SLC) in response to various fault conditions.
Subscriber
A monitoring station customer.
Subscriber Account Code
A unique number assigned by a monitoring station that uniquely identifies the customer and the protected premise.
Supervised Auxiliary Relay
An electrically operated switch contact whose wiring and operation is monitored by the control panel.
Supervising Station
A facility that receives signals and is maintained at all times to respond to these signals.
Supervision
Monitoring of a device or circuit for proper operation and the annunciation of off-normal conditions that prevent normal operation.
Supervisory Device
Equipment used to signal a condition that could prevent proper operation of guard tour, fire suppression system or related fire protection equipment.
Supervisory Signal
An indication that a device monitoring guard tour, fire suppression or related fire protection equipment has activated.
Supervisory Signal-initiating Device
Sensors used to detect condition that could prevent proper operation of guard tour, fire suppression system or related fire protection equipment. Examples include valve supervisory switches, water level indicators, and low-air pressure switches.
Supply Fan
A blower in a heating, ventilating, and air conditioning (HVAC) system that provides air to a building.
Suppression System
Equipment designed to extinguish a fire.
Surge Suppressor
An electrical circuit protective device that reduces the effect of a high voltage transients, such as a lightning spike.
Survivability
The ability of a system to be able to withstand wiring, communications, and internal faults while maintaining maximum functionality. Class A wiring, redundant equipment, peer-to-peer networking, and degraded mode operation all contribute to system survivability.
Swinger
The repetitive opening/closing of a detection circuit or device for no apparent reason.
Synchronized Notification Appliances
Visible signaling devices that flash simultaneously (within 0.01 second) at a one to two Hertz flash rate.
T
Tamper Proof
Resistant to unauthorized opening or access.
Telephone Call-In
A control panel indicator that alerts the operator of an incoming call on the two-way emergency communications system.
Temperature, Ambient
The air temperature under normally expected conditions.
Temporal Pattern
The universal evacuation signal consisting of a three-pulse pattern sent over the notification appliances to advise occupants to evacuate the building.
Thermal Detector
See Heat Detector
Thermal Lag
The delay a heat-detecting element experiences in reaching its operating temperature.
Threshold
See Alarm Threshold
Time Control
A programmed system event that is activated by the time of day, day of the week.
Toggle
The alternating ON/OFF action of a switch or operation.
Tone Generator
The electronic circuitry that creates audio alarm and alert signals that are distributed by the one-way emergency communication system.
Traditional System
A non-addressable alarm system that utilizes contact devices and circuit continuity to initiate an alarm condition and direct wired DC circuits to operate notification appliances. Also called a hardwired or conventional system.
Transponder
An addressable system interface that converts input signals to the format required by the addressable system and can convert commands from the addressable system controller into output contacts and signals.
Trouble Signal
A system indication of a fault, such as circuit break or battery failure, occurring in the devices, wiring, or associated system component.
T-tap
Branch wiring conductors. T-tapped or branch wiring should be avoided in all fire alarm installations utilizing end-of-line devices. Addressable systems typically permit T-taps unless wired for Class A operation..
Two-Wire Smoke Detector
A smoke detector that initiates an alarm condition on the same two wires that supply power to the detector. Two-wire smoke detectors must be compatibility listed with the control panel.
U
Uninterruptible Power Supply (UPS)
A battery powered device that provides standby AC power to its load in the event of a failure of the AC power mains.
V
Valve, Deluge
An electrically actuated valve used to release water into an open (deluge system) or closed (pre-action) pipe sprinkler system.
Valve, Gate
Shut-off valves used in dry pipe, air, and water piping equipment.
Verified Alarm
A system feature used to validate an alarm input by sensing an alarm condition for a minimum specified period of time, or reconfirming the alarm after the device has been reset.
Visible Notification Appliance
A signaling device such as a strobe, beacon, or flashing light that stimulates the sense of sight to indicate an alarm condition
Voice/Alarm Communication System
A one-way emergency audio signaling system that uses electronic tones, live and recorded messages to notify occupants of an emergency condition.
W
Walk Test
A one-person test mode that facilitates testing of initiating devices and circuits, as well as notification appliances and circuits. Walk tests can be either silent or audible.
Wallbox
The cabinet in which control panel equipment or devices are installed. Wallboxes may be surface, semi-flush, or flush mounted.
Warble
An electronic tone characterized by a high frequency, fast repetitive signal.
Warden Station
A permanently installed firefighters’ telephone enclosure with handset.
Watchdog
A hardware circuit that monitors the integrity of microprocessor-based electronics/software and generates a trouble condition in the event of a failure.
Water-flow Alarm
A sensor that initiates an alarm condition whenever water movement is detected in sprinkler system piping.
Weatherproof
Resistant to the effects of rain, cold, moisture, or heat. For cold climate regions, equipment may be installed with an automatic thermostat/heater unit included.
Whoop
An electronic tone characterized by a repetitive signal starting at a low frequency, then rising steadily in frequency, and then terminating.
Y
Yeow
An electronic tone characterized by a repetitive signal starting at a high frequency, then falling steadily, then ending.
Z
Zone
A defined area within a facility in which related functional elements work together. Zoned items can include alarm annunciation, security partitions, occupant notification, smoke control, ventilation, compartmentation.
Zone Disconnect
A control panel feature that disables the devices that make up a zone such that activation of any device that is part of the zone is ignored and programmed zone instructions are not executed. Primarily used for system maintenance
