Glossary of Terms

CCTV Glossary of Terms

Analogue:In reference to CCTV, this refers to systems and components that use the standard NTSC/PAL composite video formats. Digital refers to devices that use pixel formats. The definitions become blurred when you consider that DVRs convert the analogue signal into digital form to process the images internally, they convert back to analogue to output to other devices. Details aside, many people refer to analogue as old technology and digital as the new technology.
Biometrics:In CCTV biometrics refers to the hardware/software used to recognise body parts as a method of individual identification. Biometric readers can scan and identify fingerprints, Iris and Retinas. Facial recognition is another biometric recognition that comes under the category of video analytics.
CCTV:An acronym for Closed Circuit Television. Originally this was described as a system with cables directly from cameras to viewing devices with no outside world connections. The Internet has changed all that. Now you can access any DVR with browser software through the Internet.
Central Station Monitoring:Monitoring a large number of remote DVRs from a central location using remote software.
Client-Server Network:This is a network where a server (an unattended PC) stores information and shares it with the clients (the attended workstations). The clients depend on the servers for normal operation. The workstations do not necessarily talk to each other.
Client:In CCTV DVR context the Client is the PC running the remote software that accesses the DVR or other device. The device originating the video is the Server.
Covert Camera:A covert camera is not visible to the operator of the system. It is intentionally obscured from view and often used for surveillance of employees. An authorized operator with the proper password privileges can view the camera and recorded information.
Digital:In CCTV, digital refers to devices that operate in pixel formats. Analog video devices use traditional NTSC and PAL formats. The lines of difference are blurred when you consider the analogue signal is converted to digital and back again (often several times) within a traditional CCTV system. Pure end-to-end digital video is achieved using IP cameras through a network to NVRs and LCD monitors.
Dual Stream:This term is typically used to indicate a device capable of providing two different video compression methods. An example is a DVR that shows live video in M-JPEG and transmits to the remote software using MPEG-4. IP cameras often have selectable (dual-stream) transmit capability. This may sometimes refer to two streams of the same compression method with different parameter settings.
DVR:An acronym for Digital Video Recorder. All recording is on a computer hard drive and can be networked
Frame: One complete TV picture.
Lux: Unit of measurement of the intensity of light. 10 lux = 1 FC.
Matrix Switcher:

Normally used in larger camera systems, this switcher allows any of the system’s cameras to be routed to any of the systems monitors.

PTZ Pan-Tilt-Zoom:System for changing the position of a camera horizontally and vertically and of changing the field of view of the lens in order to observe a different scene. Requires special equipment at the camera and a method of controlling from the viewing area.
Resolution:The measure of the ability of a CCTV system, or one of its components, to produce detail. Medium Resolution is the description usually applied to cameras with 380 lines, mono or colour. High Resolution describes cameras with 560 lines mono or 460 lines colour.
RollResult of the loss of vertical sync, which causes the picture on a monitor to move up or down.
Saturation (colour)The vividness of a colour, which is directly related to the amplitude of the chrominance signal.
ScanningHorizontal (panning) camera motion.
Sensitivity (pickup device)The amount of light needed for the pickup device to operate.
Signal to Noise Ratio:The ratio between a useful signal and unwanted noise.
Spot Filter:A small device is used to increase the f-stop range of a lens.
Vari-focal Lens:A lens with an adjustable focal length, such as 3.5-8mm, 2.6-6mm, and 4.5-10mm.
Vertical Interval:The time of the vertical retrace.
Vertical Retrace:Return of the electron beam to the top of a TV picture tube or a camera pickup device target at the completion of the field scan.
Zoom Lens:A lens that is used as a wide-angle, standard, or telephoto lens by varying the lens focal length.

Access Control Glossary of Terms


A means of preventing the sharing of an access control credential. Anti-passback can be based upon disabling a credential for a period of time after it is used, or by remembering the credential holder’s in/out status.


The measurement of a physical trait that is unique, such as a fingerprint, hand geometry or iris pattern. In access control, this is used to identify authorized users and to grant or deny access.

CAT 5:A very common cable type that consists of several twisted pairs in an overall protective jacket. Used for network cabling and many access control data functions.
Circuit closed:

(1) An electrical circuit in which current normally flows until interrupted by the opening of a switch-type electronic component. (2) A circuit or switch in which the contacts are open during normal operations.

Circuit, open:(1) An electrical circuit in which current does not flow until permitted by the opening of a switch or a switch-type electronic component. (2) A circuit or switch in which the contacts are closed during normal operations.
Contacts:Electrically conductive points, or sell points, are used to make or break an electrical circuit mechanically.
Controller, Control Panel:A circuit board or group of circuit boards that contain programming for the operation of access control or another system.
Electric Strike:A door unlocking device that is installed in the door jamb and that works in conjunction with a mechanical lock or latch mechanism.
Electrified Lock:A mechanical locking device that has been modified to allow an electric circuit to lock or unlock it.
Electromagnetic Lock:(Magnetic Lock, Mag Lock)A device that locks/unlocks an opening without moving parts, using pure electromagnetic attraction
Fail-safe:An electric lock that automatically unlocks with any power interruptions.
Fail-secure:An electric lock that requires power to unlock. (Most fail secure devices are always unlocked for egress, however.)
Proximity:A common access card technology, proximity uses radio frequency to communicate between a card or tag and a reader without physical contact.
Reader:A device that obtains data from an access credential (card, tag, etc.) and send the data to a controller for an access decision. (Some units combine reader and controller in one device.)

Intruder Alarm Glossary of Terms

 Alarm Receiving Centre (ARC):A secure monitoring station receives and acts on alarm signals sent from the remotely monitored alarms. Signals are monitored 24hours a day and on receipt of alarms, the ARC will call police, keyholders and system installers to attend.
Bell Box:A self-contained high output two-tone sounder incorporating a strobe light for visual indication. All electronic components are contained within a secure fully tamper-proof enclosure.
Control Panel:The central part of the system, which controls the system and activates alarms.
Detector:A device is used to signal to the control panel if there is any movement in its range. Most detectors are now Dual Technology, combining Passive Infra-Red with Microwave or Ultrasound, providing greater stability and as a result fewer false alarms.
Dual-Tech:Where a single device operates on two different types of technology, eg. where a PIR and a Microwave detector is combined into one movement detector.
Duress Code:A number is chosen by the user that, if used to unset the alarm will act as normal but will also send a personal attack (code 2) signal to the ARC.
Keyfob:The wireless device that can arm and disarm the alarm system, also with a panic button for emergency alarm
Keypad:An input device that allows the user to set, unset and perform additional functions on the system.
Motion Detectors:The devices that detect the movement, there are three major motion detectors: Active Infrared Detector (AIR), Passive Infrared Detector (PIR), Microwave Motion Detector
Non-Volatile Memory (NVM):This is a memory chip in the Control Panel which remembers the programmed alarm settings when all power is removed. The NVM can usually be reset to Factory Default settings.
Passive infrared movement detectors:Intelligent devices that provide very stable detection, recognising the difference, for example, between humans and rodents. Electronic chips process the information even further to filter out false alarms.
Personal Attack Alarm:A method of manually activating the alarm by a person witnessing a crime or in danger. This alarm activation is treated by police as the highest priority, providing a rapid response.
Redcare:Redcare is a widely-deployed standard used in the UK to allow alarm systems to be continuously monitored from an ARC.
Remote keypad:A keypad located remotely from the control panel is used to set/unset/programme the alarm.
Security Grades:A system under which alarm components are graded (1 to 4) according to the level of protection they afford.
Silent Alarm:A triggered alarm that is mute without audible sounds, the alarm system still transmits the alarm signal to Central Monitoring Station.
Silent Part Set:This feature is available on most control panels. If the engineer has programmed this, when someone part-sets the panel, it will not emit any entry/exit tones. This is particularly useful if there are children in bed and there is a risk that setting the alarm system will wake them up.
Vibration Detectors:Normally fitted to door or window frames and designed to detect high and low-frequency vibration within a range. They can be adjusted to suit local conditions.
Wireless:A connection between alarm devices that does not use wires. Most wireless connections between system devices use RF wireless signals while wireless connections between security systems and central monitoring stations use cellular signals.
Zones:An alarm system with many input devices is often separated into a number of zones. Each zone has an indicator light on the keypad which presents the status of the zone. When all zones are secured alarm system is ready to be armed. In case of alarm, the control panel reports to the monitoring station condition of each zone tripped.
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