All you need to know about CCTV -Terms and Definitions!

All you need to know about CCTV -Terms and Definitions!

CCTV terms are a must-know for every professional in this field, so we decided to gather all possible information in one article for all, who may be interested in the topic. A

AC Adaptor

Ac Adaptor is also called a power supply. All CCTV devices need power for working. Each device has its own power requirements (usually 12 volts with a minimum amperage). The adaptor converts the AC power to DC power and will adjust it to a specified amperage. The power supply is generally included with the item bought, you don`t have to buy these separately.


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 

An input connection to a security VCR or DVR that triggers the unit to start recording if the alarm is triggered.


There are two main ways of doing things electronically, analog or digital. An analog signal can be represented as a series of sine waves. The term originated because the modulation of the carrier wave is analogous to the fluctuations of the human voice or other sound that is being transmitted.

Angle of view 

For security cameras, this refers to the angular range in degrees that you can focus the camera on without distorting the image. When focusing close up, you can generally see a wide angle of view. If the focus is distant, the angle of view is smaller or narrower.


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.

Asymmetrical Digital Subscriber Line (ADSL) 

A method for moving data over regular phone lines. An ADSL circuit is much faster than a regular phone connection, and the wires used are the same wires used for regular phone service. ADSL supports data rates of from 1.5 to 9 Mbps when receiving data (known as the downstream rate) and from 16 to 640 Kbps when sending data (known as the upstream rate). ADSL requires a special ADSL modem.

Audio/Video Interleave (AVI)

An AVI file is a sound and motion picture file that conforms to the Microsoft Windows Resource Interchange File Format (RIFF) specification. AVI files (which end with an .avi extension) require a special player that may be included with your web browser.

Auto Balance

A system for detecting errors in colour 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 Iris

A lens in which the aperture automatically opens or closes to maintain proper light levels on the faceplate of the camera pickup device.

Automatic Brightness Control

In display devices, the self-acting mechanism which controls brightness of the device as a function of ambient light.

Automatic Gain Control

A process by which gain is automatically adjusted as a function of input or other specified parameter.

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 White Balance 

A feature on colour cameras that constantly monitors the light and adjusts its colour to maintain white areas.


Back Light Compensation (BLC)

A feature on newer CCD cameras which electronically compensates for high background lighting to give detail which would normally be silhouetted.


The bandwidth determines the rate at which video can be sent through a network – the greater the bandwidth, the more video that can be sent in a given amount of time. Usually measured in bits-per-second.


A bitmap is digital graphic that basically consists of a map of dots. Bitmaps include GIF, JPEG and other file formats.

BNC connector 

Is a type of connector used to interconnect two coaxial cables or connect a cable with other CCTV components.


The attribute of visual perception in accordance with which an area appear to emit more of less light.


A general term for different types of high-speed, high-bandwidth connections to the Internet, including ADSL and cable.


Category (CAT) 5 Cable

Cable that is capable of transmitting data at high speeds (100 megabits per second and faster). CAT 5 cable is commonly used for voice and data applications.

Category (CAT) 6 Cable

Standardized twisted pair cable for Ethernet and other network physical layers that is backward compatible with the Category 5/5e and Category 3 cable standards.


Common abbreviation for Closed-Circuit Television.

Circuit Switched Data (CSD) 

A GSM transmission standard that allows data to be transferred at up to 14.4kbps.

CMOS   Complementary Metal Oxide Semiconductor.

Similar to a CCD, it also detects light for conversion into a signal. Lesser image clarity than CCD, but more compact in size with lower power usage.

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.


Short for compressor/decompressor, a codec is any technology for compressing and decompressing data. Codecs can be implemented in software, hardware, or a combination of both. Examples of Codecs include Wavelet, MPEG-4, JPEG.

Composite Video Signal (CVS)

The combined picture signal, including vertical and horizontal blanking and synchronizing signals.

Compression Technology

This is the Codecs used for compressing and decompressing video data.


The range of light to dark values in a picture or the ratio between the maximum and minimum brightness values.


Day/Night Cameras 

Day/Night Cameras are regular cameras with an especially sensitive CCD chip that allows a good image to be captured in very low ambient lighting.


The fidelity of a television system to the original scene.

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.

Digital Video Recorder (DVR)

A digital video recorder is basically a computer that converts the incoming (analog) signal from the cameras to digital, and compresses it, and stores it. The DVR replaces the function of a multiplexer (or quad or switcher) and a security VCR. There are many advantages of digital video recorders over their analog counterparts.


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.


The downloading of data from the Internet to the PC. ADSL has both upstream and downstream data rates.


A circuit that permits transmission in both directions. In CCTV, duplex is often used to describe the type of multiplexer that can perform two functions simultaneously: recording in multiplex mode and playback in multiplex mode.

Dynamic IP address 

The term used to describe how an IP address is dynamically assigned to computers as and when needed. Unlike Static IP addresses, the IP address is temporary e.g. when you connect to your ISP using a dial-up connection , you PC or router will be dynamically assigned an IP address whilst you are on-line. This form of IP addressing is commonly used for consumer ADSL service.



A firewall is a set of related programs, located at a network gateway server, that protects the resources of a private network from users from other networks.

Focal Length

Of a lens, the distance from the focal point to the principal point of the lens.

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.


The total area, occupied by the television picture, which is scanned while the picture signal is not blanked.

Frames per Second (fps)

This refers to the number of pictures that can be recorded or displayed per second. A television displays 25fps and is referred to as real time. This should not be confused with fields per second. Two fields per second is equivalent to one frame per second.


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. G


An increase in voltage or power, usually expressed in dB.


A piece of hardware that acts as the ‘gate’ between a LAN and the internet. The Gateway address is simply the IP address of the Gateway.

General Packet Radio Service (GPRS)

Part of the GSM standard that delivers “always-on” wireless packet data services to GSM customers. GPRS can provide packet data speeds of up to 115 kb/s.


A spurious image resulting from an echo.

Gigabyte (GB)

This unit is typically used to measure large data storage or data transfer capacities (by current standards). 1GB = 1024 MB = 1,048,576 KB = 1,073,741,824 bytes.

Terabyte (TB)

Measure of storage capacity that is 2 to the 40th power, or approximately a trillion bytes. A terabyte is more precisely defined as 1,024 gigabytes (GB).

Global System for Mobile Communications (GSM)

The communication system used by cellular phones in the UK.

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. H

H.264 Compression

It is generated from MPEG-4, but more advanced for video compression. H.264 Compression has more complex coding algorithm, lower usage of bandwidth and smaller royal fee than MPEG4. It works well on a very wide variety of applications, networks and systems (e.g., for broadcast, DVD storage, and multimedia telephony systems).

Hard Disk Drive (HDD)

The storage device usually fixed inside of your computer or DVR used to store information.

High Speed Circuit Switched Data (HSCSD)

 A GSM transmission standard that allows data to be transferred at up to 28.8kbps


This technology delivers high quality live HD video over coax with exceptional resolution and image detail. HD-SDI technology delivers image quality that is far superior to analog CCTV and provides a cost-effective video surveillance solution that’s easy to install and integrate with existing CCTV systems. Before HD-SDI, the only way to get HD resolution was through a megapixel IP camera. HD-SDI is the future of analog and an alternative to IP.

HDMI Output

HDMI supports standard, enhanced or HD video. Some DVRs feature an HDMI output which delivers enhanced image clarity with crisp images and enables you to view your security camera video in HD on your HDTV screen. HD images can be reproduced with the HDMI support for HD display.

Hertz (Hz)

The number of variations per second (e.g. picture frames, alternating of the current, etc).


Hyper text transfer protocol. HTTP Port 80 Normally this is the HTTP port address that cameras can communicate over.

Hybrid DVR 

Supports both analog and IP cameras, enabling you to utilize existing legacy analog technology, while providing flexibility to migrate to an IP solution and take advantage of the many benefits of IP technology. I


The input or output characteristic of a system component that determines the type of transmission cable to be used. Expressed in ohms.

Infrared (IR)

Infrared (IR) cameras feature built-in illuminators that project infrared light, which is nearly invisible to the human eye but very visible to IR surveillance cameras. This technology allows you to capture crystal clear, black and white video of suspects who feel protected by complete darkness. IR cameras are very effective in covering targeted areas with little or no light, ranging from exterior parking areas and entryways, to interior rooms requiring 24 hour surveillance. For coverage of wider areas, consider adding an additional external infrared illuminator.

Input/Output (I/O) Device

An I/O device facilitates elevator control and multi-door monitoring (in/out only).

Internet Protocol (IP)

The primary communications protocol in the internet protocol suite for sending and receiving data packets across network boundaries.

IP-based Access Control

IP access control technology utilizes the network to provide secure network-controlled access and management of physical doors at a facility or location.

IP Address

The network location of an IP camera, which can be located using a Web browser on a PC.

IP Rating

IP rating is a standard rating of protection offered by an enclosure. An IP rating consists of the letters “IP” followed by two a two-digit number. The first number represents the level of protection an enclosure has against solids, moving parts and dust, and the second number represents the level of protection against moisture, fluids and water.

IR Illuminator Wavelengths

It  works with day/night cameras to provide IR illumination for low light environments and enable you to capture video at night. IR illuminators are equipped with varying wavelengths—generally from 730 nm to 950 nm. An IR illuminator with a 730 nm wavelength requires a less light sensitive camera and produces a strong, very visible red glow, while an 850 nm wavelength IR illuminator produces a faint visible glow, making it semi-covert. An IR illuminator with a 940 nm wavelength produces a glow that is virtually invisible to the human eye, which makes it an ideal choice for most covert applications. A 940 nm illuminator must be used with a very light sensitive camera with no IR cut filter, or if the camera does have an IR filter, it has to be removed for optimal results.


Mechanism within a lens to regulate the amount of light that passes through, and falls upon, the image sensor. It can be controlled manually or automatically. J


Stands for `Joint Photographic Experts Group` who designed the standard. This is a standard way of compressing images which works particularly well for photographic images (as opposed to graphic art).


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.

Junction Box Mounting

Outdoor dome cameras feature J box mounting enabling the camera to be directly mounted to an installed junction box, providing faster, easier installation. L

LAN (Local Area Network)

A communications system that links computers into a network, usually via a wiring based cabling scheme. LANs connect PCs, workstations and servers together to allow users to communicate and share resources like hard disk storage and printers.


A transparent optical component consisting of one or more pieces of optical glass with surfaces curved (usually spherical), so that they converge or diverge the transmitted rays of an object, forming a real or virtual image of that object.

Lens Format

The approximate size of a lens-projected image. In most cases the lens will project an image slightly greater than the designated image size to insure the pickup device is completely covered. It is recommended that camera and lenses are the same format size. A lens larger format size can be used on a smaller format camera, however a smaller format lens should never be used with a larger format camera.

Lens Speed

Refers to the lens aperture or its ability to transmit light. This is measured in F-stops.

Line Locked

A camera that is synchronized to the frequency of its AC power supply.

Local De-warping

Some fisheye or 360 cameras feature local de-warping which enables viewing of portions of the full video image produced by the fisheye without distortion.

Loop Out

A loop out connection enables you to run video stream from a single camera to a separate monitor on every channel. This feature is especially ideal for public view monitors and reception desks.

Loss Detection

The automatic video loss detection feature allows you to program your DVR to alert you when your camera loses its signal due to power failure, bad weather or tampering. You can get an alert from an external device such as an alarm or trigger another camera to start recording.


A unit of incident light. It is the illumination on a surface one square foot in area on which a flux of one lumen  uniformly distributes, or the illumination at a surface all points of which are at a distance of one foot from a uniform source of one candela.


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).


International System (Sl) unit of illumination in which the meter is the unit of length. One lux equals one lumen per square meter. M

Magnetic Contact

A device that sends a signal when the magnetic field between two monitored access points breaks.

Magnetic Lock (Mag Lock)

A locking device that consists of an electromagnet and a strike plate that works in conjunction with a mechanical lock or latch mechanism. Thus it uses electromagnetic attraction to lock and unlock a door.

Manual Iris Lens

A lens with a manual adjustment to set the iris opening (aperture) to a fixed position. This type lens is generally used in fixed lighting conditions.

Matrix Switcher

A combination of electromechanical or electronic switches which route a number of signal sources to one or more designations.


Pixels are used as a unit of measure. In the security industry, it’s a measure of resolution. Mega refers to 1 million, therefore, megapixel means one million pixels. If you have a 2.0 megapixel camera, in actuality you have a 2 million pixel camera.


MIMO (multiple in, multiple out) is a method of utilizing multiple radio antennas at both the transmitter and the receiver to improve communication performance for wireless network communications.


Black and white with all shades of gray.

Motion Detection

This is a feature that detects motion within a video signal. Normally this is used to trigger recording of images. Advanced motion detection systems have the facility to adjust the sensitivity and object size that will trigger the system. They also allow the image to be blocked out, such that only certain areas of the image are taken into account when scanning for motion.


Moving Picture Experts Group, version 4. A form of compression that makes transmission and storage of images easier.

Multiplex Operation

Multiplex operation enables simultaneous live viewing, recording, playback, and backup. This allows you to view live video from your DVR locally or via your network, play back existing recorded video, or make backups without stopping recording.


Enables you to set your recording resolution at one rate and watch live video at another rate.


An access control software feature that quickly verifies where individuals in a particular zone at a location for easy tracking and identification.

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 IP Camera

An IP (internet protocol) or network IP camera captures and transmits live and recorded video images directly over a network. A network camera requires a high speed internet connection, router, Ethernet cable and IP address to function, and it plugs directly into your network router and transmits data through the network.

Network Video Recorder (NVR)

An NVR is a hardware box that receives video streams over a LAN (local area network) or WAN (wide area network) and records the video streams in digital format onto a hard disk. Recording and playback of video can be managed remotely from any compatible device such as a PC, laptop or smartphone that is connected to the network.


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”.


Network time protocol.

NTP Server

A central source that can set the time of all network devices.


National Television Standards Committee. Color Video Signal standard used in North American and Japanese: 525 Lines, 60Hz.

O On Screen Display

A camera’s On Screen Display (OSD) allows you to fine tune virtually every setting of your camera to achieve the best possible image quality. Without OSD, you are dependent upon the factory settings of the camera, and subject to any impact to the camera experienced during delivery or installation. With the convenient design features of DIGIOP Black cameras, including 2nd video out and on-board one-finger joystick controls, you can adjust your every aspect of your camera at the point of installation – without having to run back-and-forth to your DVR or monitor. Aspects you can control include wide dynamic range, auto iris exposure settings, day/night settings, and many more.

ONVIF Compliant

An ONVIF compliant product conforms to ONVIF (Open Network Video Interface Forum) specifications for IP-based security products. ONVIF defines a common protocol for the exchange of information between different network video devices from different manufacturers, to allow greater interoperability in multi- vendor network video systems.


The signal level at the output of an amplifier or other device.

Overwrite Protection

This optional feature allows you to prevent files from being overwritten when the hard drive is full, or you can pre-program the DVR to overwrite recorded video to ensure continuous recording—it’s your choice. P

Pan & Tilt

A device that can be remotely controlled to provide both vertical and horizontal movement for a camera.


The measurement of a video signal from the base of the sync pulse to the top of the white level. In order to gain a full video signal this should be one volt.

Peer-to-Peer Communication

Some IP-based door controllers in an access control system are independent of a network or PC work station. Generally, they feature peer-to-peer communication which keeps data flowing, even if a server connection is interrupted.

Phase Adjustable

The ability to delay the line locking process so as to align cameras fed from AC voltages of different phases.

Photo Detector

A device at the receiving end of an optical fiber link that converts light to electrical power.


A device that automatically switches on the infra-red lights when light levels fall to a pre-set level.

Power over Ethernet

PoE allows IP (internet protocol) devices to receive power and data over existing LAN (local area network) cabling; eliminating the need to install a separate power cable, simplifying installation and lowering cabling costs.

Power Over Ethernet+ (PoE+)

This feature enables high-draw PTZ camera to utilize Power over Ethernet (PoE) on a single CAT5 cable.

Progressive Scan

Video signals stream using horizontal lines. Progressive scan, also referred to as non-interlaced scanning, draws every line of an image in sequence. The main advantage with progressive scan is that motion appears smoother and more realistic.


A common access control card technology that uses radio frequency to communicate between a proximity card and a reader.

Proximity Card (Prox Card)

A access control credential that is encrypted with proximity technology and can be read by a proximity reader without having to physically insert the card into the reader, in order to grant a cardholder access to a location.

Proximity Reader (Prox Reader)

A device that can read encoding on access control credentials such as a proximity card or badge, and sends data to a controller to grant or deny access.

PTZ (Pan, Tilt Zoom)

A pan-tilt-zoom camera is a camera that is capable of remote directional and zoom control.

Q Quad Splitter

A product that can display the views from 4 cameras simultaneously on one monitor. It is also possible to select any individual camera so as to view full-screen display on real time monitoring, dependent on model.

R Random Interlace

A method of combining two fields to make one frame where strict timing is not a requirement.

Request to Exit Button (REX) 

In access control, a button that must be pushed to release the door in order to exit.


The ratio of light returned from a surface expressed as a percentage.

Reflected Light

Scene illumination multiplied by reflectance. This is the amount of light returned to the camera and determines the quality of picture. Refracted Index Profile A description shown in the form of a diagram illustrating how the optical density of an optical fiber alters across its diameter.


Devices placed at regular intervals along a transmission line to detect weak signals and re-transmit them. These are seldom required in fiber optic systems. (Often incorrectly referred to as ‘repeaters’).

Remote Switcher

A video switcher to which the cables from the cameras are connected 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.

RS-485 Controls

RS-485 controls allow camera settings to be changed remotely without the operator being physically present at the camera location. This is done by using an RS-485 controller which is typically set up at the viewing station or control room. S

SD Card Slot

Provides convenient offloading of video onto an SD card.


Sense-up automatically enhances DSS (digital slow shutter) and keeps the shutter open for a long time to allow extra light into the camera to produce brighter images in low light conditions.


For a camera usually specified in lux to provide indication of light level required to gain a full video signal from the camera. Shutter Ability to control the integration (of light) time to the sensor to less than 1/60 second.

Signal-to-Noise Ratio

Signal to noise ratio, a measurement of the noise level in a signal expressed in dB (decibels). In a video signal values from 45dB to 60dB produce an acceptable picture. Less than 40dB is likely to produce a “noisy” picture.

Smart Card

An access card that can be integrated with different technologies including biometric, magnetic stripe, proprietary proximity, and contain information about the cardholder.


Most cameras are not able to adjust IR output based on object distance, which often results in a washout for over-IR-exposed scenes, or a darkened image for under-IR-exposed scenes. This features allows the camera to automatically adjust IR intensity as the subject moves closer to or further away from the camera, so you always have a clear image that is not washed out or too dark.

Smart Zoom

Smart zoom automatically digitally zooms in on areas the camera senses motion in, so as to get a more detailed image and then zooms back out.

Spot Filter

A neutral density filter placed at the center of one of the elements (or on an iris blade) to increase the high end of the F-stop range of the lens.

Sun/Rain Shield

Some cameras come with an adjustable sun/rain shield to prevent glare and direct contact from the elements, in order to deliver the cleanest possible video signal.


The first-of-its-kind SwitchBox NVR delivers an IP network recording solution—without the complexity. The SwitchBox NVR features an integrated 4 or 8-port PoE (Power over Ethernet) network switch to power the IP network cameras directly through the network cable—eliminating the need to purchase a separate network switch. The all-in-one SwitchBox NVR delivers an easy-to-install, plug-and-play IP- based recording solution.

Tampering Detection

Tamper detection is a tamper notification feature that sends an alert if the viewing angle of the cameras changes, or even if the viewing area has been blocked.


The system by which a signal transmits to a remote location in order to control the operation of equipment. In CCTV systems this mainly includes controlling pan, tilt and zoom functions, switch on lights, move to pre-set positions etc. The controller at the operating position is the transmit

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Author Armen Begoyan