Glossary for video surveillance system and alarm system

This is a great sources that works as a dictionary provides the basic terms information that usually used in video surveillance system and burglar alarm system, this glossary for video surveillance system and alarm system that can helps a lot of people on understanding much more on these equipment. Below we provided information only for reference purpose, the information are collected from Internet, may not accurate.




A.L.C. (Automatic Level Control):

On AI lenses, also known as the peak/average control. Adjusting this control 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 darker areas.

Acoustic echo cancellation:

A method for removing acoustic feedback between a loudspeaker and a microphone in loud-speaking audio system.


A Microsoft open technology for Windows-based applications. ActiveX controls can be downloaded as part of a Web document to add functionality to the ActiveX- enabled browser, e.g. Internet Explorer.

Activity Detection

A feature of the Generation 3 video multiplexer range that uses video motion detection techniques to improve the camera update times. It also gives a relay closure.

AC Voltage

A voltage that is constantly chaning in both amplitude and polarity. AC voltage are widely used in most of our home appliance. Typically, there are two different AC voltage around the world; 110V (60Hz) and 220V (50Hz)

Acoustic Sensor

A device that is designed to detect and respond to sound.


Automatic Electronic Shutter, the sensor will automatically adjust the sensitivity according to the changes in illumination of detected area.

AF (Auto Focus)

An ability by which the camera lens automatically adjusts its focus on the captured subject.


Automatic Gain Control, an electronic circuit which amplifies the video signal when the signal strength falls below a given value due to the lack the light on the image device.

Alarm System

A System that consist of "Input Devices" (magnetic contact switch, Motion Detectors , IR Beam Detectors , Glass Break Detectors , Smoke Detectors, Vibration Detector etc..) , "Processing Unit" (Control Panel or alarm host) and "Output Devices" (sirens , strobe siren, Phone Interface , Smoke Generator , etc..)


A signal in which any level is represented by a directly proportional voltage; not digital.


To activate the alarm system into an Arm mode.


A special type of iris, is used to adjust the amount of enter light, electrically controlled by the camera.There are two main types of AutoIRIS - Video and DC IRIS. See also Video IRIS and DC IRIS.


Automatic White Balance, is used in digital camera to automatically compensate the type of light (daylight, fluorescent, incandescent, etc.,) or lighting conditions in the scene.To make it normal for the human eye.

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A backup power supply that can be rechargeable to provide power in case of AC failure.


The science of identifying an individual based on physiological or behavioral inputs.

Bit rate:

A unit of speed, defines the number of bits/ time unit, usually expressed in Kbit/s or Mbit/s.

Bells/Sirens (interior and external):

Visual and audible bells alert your family and neighbors of an alarm situation in your home.

BNC (Bayonet Nut Connector)

Video connector, the most commonly used in CCTV.

Burglar Alarm System:

The system that combines detector and processing unit that detect the intrusions, fire alarm, panic...etc.

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CCD (Charged Coupled Device)

Charged Coupled Device, an electronic detector made of silicon that converts light energy into electronic signals. It is used in many digital cameras for image detection.


Closed Circuit Television: A video surveillance system (closed circuit television) that allows you to observe high risk areas and/or sensitive transactions.

C Mount / CS Mount

The two industry standards for mounting a lens on a camera. The C-Mount lens has a 17.5mm flange back distance. The CS-Mount lens has a 12.5mm flange back distance.

Central Monitoring Station

The station that provides the link between alarm system and authorities department for providing 24hours monitoring service.

CMOS (Complementary Metal-Oxide Semiconductor)

Complementary Metal-Oxide Semiconductor, one type of image sensor in digital cameras.CMOS chips are easier and cheaper to make than CCDs but don't match the picture quality generally.

Coaxial cable

It is used to transmitting analog video in a CCTV system. It is an electrical cable that consists two conductors, separated by an insulating layer.

Contact ID

It's fast DTMF communication format, also called ADEMCO Contact ID. It is developed by ADEMCO used for alarm transmission from alarm system to Central Monitoring Station.

Control Panel

The processing unit (brain) for alarm system that receive information from all detectors, then process the information and trigger the alarm.

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Day and Night IR LENS

The camera with this feature will automatically detects available light and instantly adjust the brightness and gain under low light condition by switching to Infra-Red(IR) black and white mode.

DB (Decibel)

Decibel widely used to measure the loudness of sound. The decibel is more generally a measure of the ratio between two quantities,and can be used to express a variety of measurements in acoustics and electronics.

DC Voltage

Direct Current is the type of electricity. All of the electric charges move in one direction. (Opposit AC Voltage)

DDNS(Dynamic Domain Name Service)

Dynamic Domain Name Service is a service that maps Internet domain names to IP addresses. It works with dynamic IP addresses.

Delay Zones

Any zone that after has been violated ,waits a predetermined time before triggering an alarm. This type of zone is related to entry doors into the premises.


A decoder is a device that is undoing the encoding so that the original information can be retrieved. Just as the reverse of an encoder.


Deactivate the alarm system or turn off the alarm system.

DIY Alarm System

Do it yourself alarm system that can be easily install and operation by users, normally they are wireless kits.

Door/Window Magnetic Contact

A detector that sensing the open and close for doors and windows.

Dual Tech Motion Detector

The Motion detector that combined with PIR and Microwave detectors for detection of true intruder.

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Electronic shutter

One of the major features of CCD cameras, works with the IRIS setting. It eliminates the blurry image of fast-moving subjects in higher shutter speeds.

EOL Resistor(End of Line)

End of line resistor that provides the cable protection between detectors (zone) and alarm panel.


An encoder is used to encode a bitstream into a form that is acceptable for transmission. Inside video cameras, that changes individual component signals into composite signals.

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False Alarm

A situation were an alarm signal is triggered without any intrusion attempt . Some causes of this are user error (accounts for over 80%) , telephone line trouble and equipment malfunction.

Fiber Optic

The process of transmitting light through a long, flexible fiber such as glass or plastic, for the purpose of transmitting video, audio, or data over long distances.

Fire Protection

Can consist of services such as smoke detectors, manual pull stations,  water flow and gate valve switches (fire sprinkler systems).  These fire alarms are monitored by our 24-Hour Local Central Station the operators will in turn dispatch the proper fire department.

Fire Detector

Commonly a smoke detector or heat detector

Frame Rate

The rate at which video frames are displayed on a monitor per second. Real time Frame rate for PAL is 25 fps, and frame rate for NTSC is 30 fps.

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Gas Detector

The detectors that are designed to detect the gas leaking or density of gas.

Glass Break Detectors

The sensor devises sense or detect the special sound of breaking window glass.  When the sound is detected an alarm is sent to CMS.


An electrical connection point that is common to either a metal chassis, a terminal, or a ground bus.

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H.264 Compression Format

H.264 is a next-generation video compression format. H.264 is also known as MPEG-4 AVC. Developed for use in high definition systems.

Hardwired Alarm System

The alarm system that detectors are connecting with alarm panel via cables (physical wired). Compare to wireless alarm system, hardwired alarm system are not interfered by the wireless signal or RF radio.

Horizontal Resolution

The maximum number of individual picture elements that can be distinguished in a single scanning line.

Hybrid Alarm System

The alarm system with wireless zones and hardwired zones can support wireless detectors and hardwired detectors.

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Instant Zone

Any zone that after it has been violated , trigger an alarm condition with no delay.

IP Waterproof Rating (IP66 - IP68)

The IP rating means that product is protected against the ingress of solid object and water. Many cameras or camera housings are designed for outdoor use, and therefore need to be waterproof. The first digital is the protection against solids, and the second digital is the protection against water. Refer to the above table for details;

IR Lens

A kind of lens; used in the color cameras for detecting the Infrared radiation. See also Infrared (IR).

IR Cut filter

Infrared-radiation cut filer, is a color filter used in color CCD or CMOS, in order to block the infrared light and make the colors more realistic.


The adjustable opening (mechanical diaphragm) through which light can pass and be regulated.

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The wireless device that can Arm and Disarm the alarm system, also with panic button for emergency alarm.


The device that for programming and operation of alarm systems. The keypad can display the alarm system status, alarm information, event log...etc.



LAN (Local Area Network)

Local Area Network; is a network that allows multiple computers or other devices to be connected to each other. In order to share data or a resource or file storage space.


A transparent optical component that converges light rays to form a two dimensional image of that object.

License Plate Recognition

License plate recognition requires specialized equipment in order to successfully overcome the challenges related to speed, lighting, reflectivity and headlight glare. Cameras chosen should be designed specifically for license plate reading as most conventional cameras will not work on a consistent basis. Infrared lighting is typically required for performance during both day and night.

Local Alarm System

The Alarm System that only setoff Siren or Bell when alarm is triggered. It works as the driveway alarm system.

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Manual iris

One kind of iris, opposite of an Auto IRIS. Manually adjust the camera iris to regulate the amount of light allowed to reach the image sensor.


Radio frequencies between 1 - 30 GHz used for video transmission over medium/long distance.

Motion Detectors

The devices that detect the movement, there are three major motion detectors: Active Infrared Detector (AIR), Passive Infrared Detector (PIR), Mircowave Motion Detector.

Motion Detection

Motion detection is used to trigger motion events for DVR. Enable it by adding a new detected window, window name, sensitivity and percentage.

Master user code

Usually it's installer code, it top administrator password with unlimitated access alarm system. it can used for programming and setting for alarm system.

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NTSC (National Television Systems Committee)

National Television Systems Committee; is the most popular video display standard in North America.NTSC uses 525 TV lines per frame and frame rate is 30 frames per second.

Normally Closed

Electircal contacts in a switch, relay or other device that are closed when not activated by an external force.

Normally Open

Electrical contacts in a switch, relay or other device that are opened when not activated by an external force.



Optical Zoom

Optical zoom amplify the image size by adjusting the lens. It enlarges the subject without sacrificing resolution.

Open Circuit

An electrical circuit that is not a complete path for the flow or electrons and therefore current folow is not possible.

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PAL (Phase Alternating Line)

Phase Alternating Line, is a video display standard used in Europe, Asia and certain other parts of the world.PAL uses 625 TV lines per frame and frame rate is 25 frames per second.


Side-to-side movement of a camera (on a horizontal axis).

Panic Alarm

An alarm generated for emergency conditions.


A section area which can be controlled and operate independently for other sections.

Perimeter Alarm System

The alarm system that provides perimeter protection. The idea behind perimeter protection is that you can detect the intruder before they enter into your house.

Pixel (Picture Element)

Stands for picture element, the smallest bit of data in a video image.

POE (Power over Ethernet)

Power over Ethernet, a technology used to transmit electrical power along with the data.It is used in IP-Surveillance and remote monitoring in places where it is inconvenient to feed the devices power from a power outlet.

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Quarter CIF, or Quarter Common Intermediate Format. It refers to video with dimensions of 176 by 144 pixels usually.



Remote Arm/Disarm

User access the alarm system remotely via telephone, GSM, Internet to Arm/Disarm.


The wireless device that can received the alarm signal and retransmits it at a long distance. This device is used for increasing the wireless transmission between alarm system and wireless detectors.


A commonly used computer serial interface.


RS-485 is an electrical specification of a two-wire, half-duplex, multipoint serial connection.It supports high data transmission speeds and uses a different balanced line over twisted pair. It also spans large distances.

RTP (Real-Time Transport Protocol)

Real-time Transport Protocol; is the protocol used to transport the multimedia stream to the client.It sends a packet to the network but cannot warrant that the packet will reach its destination.

RTSP (Real Time Streaming Protocol)

Real-Time Streaming Protocol; is mandated to manage the streaming session. This is called the Internet Remote Control. It allows the client to know about available streams at a location, get stream parameters...etc. It also allows to PLAY, PAUSE, STOP, just what you generally expect from a remote control.

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Sensors (Detectors)

A device that indicates a change of state in response to an event or stimulus.

Silent Alarm

Triggered alarm that in mute without audible sounds, the alarm system still transmit the alarm signal to Central Monitoring Station.


One of important device for security system that make a loud noise to scare the intruder or alert neighbhour.


Sharpness describes the clarity of detail in a image.

S/N ratio

The ratio of the value of the signal to that of the noise (expressed in decibels). The higher the number, the better.


Super HAD (Hole Accumulation Diode) CCDs allow more light to pass to each pixel, increasing sensitivity and reducing noise.


Abbreviation for synchronization. Electronic pulses that are inserted in to video signal for the purpose of assembling the picture information in the correct position.

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Temperature Detector

Heat detector that detect the changes of temperature, mainly used for fire detection.


Rotating the camera upward or downward.

TVL (Television Lines - Resolution)

The maximum number of changes between light and dark on a picture across 3/4 of the width dictates the resolution of a CCTV product, measured in TVL.



UDP (User Datagram Protocol)

User Datagram Protocol; is a communication protocol used for data transmission between network devices.UDP does not provide mechanisms for error detection and error correction between the source and the destination.

User Code

A digit code used to Arm and Disarm the security system. Many alarm systems are support multi user code.

UPS (Uninterrupted Power Supply)

Equipment that supplies power to a system in the event the primary power is lost. It may consist of batteries or auxiliary motor generators.

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To completely avoid the camera from external impact and make it ideal for video surveillance outdoors.

Varifocal lens

A lens, that has a variable focal length that can set manually.See Zoom Lens. Usually not motorized (manual).


VGA (Video Graphics Array) is a connector for video device for transmission of video. VGA connectors are mainly used in Computer and Monitor, Security DVR...etc.




A protection for the camera from the adverse environmental conditions.

White Light

The entire spectrum of visible light.


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.








An alarm system with many input devices is often separated into a number of areas called ZONES. Each zone has an indicator light on the keypad which present status of the zone. When all zones are secured alarm system is ready to be armed. In case of alarm ,Control Panel report to the monitoring station condition of each zone tripped .

Zone Attributes

Programmable options to defince the zones applications and functions.

Zoom lens

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Tags: Alarm system, Surveillance System