Glossary

Definition of Terms

1080i/p
A term to denote 1080 horizontal scan lines of a display (vertical resolution). The i/p denotes whether the display is interlaced or progressive scanned (non-interlaced). The phrase is often used in conjunction with High Definition displays.

485 Bus
Flexible, addressable interconnection method used to link DVRs, Remote Keyboards, Alarm input modules, Relay Output modules and other equipment to form powerful systems with minimum cabling.

720i/p
A standard industry term, denoting 720 horizontal scan lines of a display (vertical resolution). The i/p denotes whether the display is interlaced or progressive scanned (non-interlaced). The phrase is often used in conjunction with High Definition displays.

Activity Detection
A facility where the amount of movement within programmable areas of a camera picture is constantly measured. If the amount of movement in the sensitive areas exceeds a preset value, this can trigger action such as increased recording rate or sounding an alert buzzer. 

Advanced Activity Search
The facility to retrospectively search the video recording for when movement has occurred in selected areas of the picture. This does not require activity detection or video motion detection to the active at the time of the recording.

Alarm Reporting
The facility to notify events such as alarm detection or camera failure to a remote monitoring centre.

Alarm Zones
See 'Zoned Alarms'

Alarming
Feature on some CCTV equipment which allows the equipment to provide a simple switch closure (usually) in response to a designated input alarm signal. 

Analytics
Software used in conjunction with a DVR, video server or edge device such as a camera to perform analysis of a scene, typically as a live analysis where the analytics is reviewing events as and when they occur, raising alarms to the operator if necessary. Analytics can be activities such as monitoring for removal of an object, perimeter/tripwire detection and people counting. The use of ANPR is also categorised as a form of analytics, as is more traditional forms of video analysis such as Video Motion Detection (VMD).

ANPR
Automatic Number Plate Recognition (ANPR) is a form of video analytics that captures, and stores vehicle license plates from a specialised ANPR Camera.

Aperture Opening (Lens)
Controls the amount of light reaching the surface of the camera pick-up device. Aperture size is controlled by the iris. Increasing the f-stop decreases the amount of light reaching the pick-up device.

Aspect Ratio
Ratio of picture height to picture width. Standard ratio is 4:3. 

Attenuation
A decrease in signal strength.

Audio
The use of sound to provide added functionality e.g. listening in to sounds on a remote site or passing audible warnings to trespassers at a camera location.

Auto Iris Lens
Camera lens which automatically adjust for proper light levels 

Auto Pan
Automatic back and forth camera motion 

Auto Scan
Same as Auto Pan 

Automatic Brightness Control
Electronic circuitry which automatically controls the brightness of video monitors in relation to ambient light.

Automatic Frequency Control (AFC)
Circuitry that automatically maintains the desired frequency. 

Automatic Gain Control (AGC)
Circuitry that automatically adjust the signal to proper strength. 

Automatic Light Control
Process by which the brightness upon the camera pick-up device is automatically adjusted according to the brightness of the scene. 

Bandpass
Specific range of frequencies allowed to pass through a device 

Bandpass Filter
Filter that passes only a specific band of frequencies 

Bandwidth
Range of frequencies in which a specific device will properly operate 

Bi-directional audio
Use of sound from both the camera locations and the operator control position. This can be used to listen in to the camera sites and give audible warnings to intruders and trespassers seen on the CCTV pictures. 

Bit
Binary Digit. The bit is the smallest unit of data currently used in digital storage and transmission. A single bit is a one or a zero.

Blooming
Defocusing effect that occurs around bright areas of a picture when an increase in brightness occurs. 

BNC
Most commonly used video cable connector in CCTV equipment. The name derives from Bayonet, Neill and Concelman, developers of the connector. 

Bridging
When a high impedance video line is paralleled, usually through a switch, to a source of video.

BS8418
British Standard which gives a code of practice for the design and operation of Remotely Monitored Detector- Activated CCTV Systems.

BS8495
British code of practice for digital CCTV recording systems for the purpose of image export to be used as evidence. 

Byte
A group of 8 bits.

C-Mount
Former industrial standard lens mounting format 

Candlepower
Unit measure of incident light 

Cat 5, Cat 6
Abbreviation for Category 5 or Category 6 cable. These typically contain 4 twisted pairs and are the most types used for Ethernet network cabling. These cables can also be used in CCTV applications to transmit video signals, alongside power, audio and power.

CCD (Charged Coupled Device)
The "chip" in a solid state camera that replaced the camera tube . 

CCTV
Closed Circuit Television

CIF Resolution (QCIF, CIF, 2CIF, 4CIF, SIF)
CIF - Common Intermediate Format - a set of standard video formats, defined by their resolution. CIF resolution is 352 x 288 pixels, also known as Full CIF (FCIF). QCIF is Quarter CIF (resolution 176x144) 2CIF is Two-times CIF (resolution 704 x 288) 4CIF is Four-times CIF (resolution 704x576) SIF has a number of name definitions e.g. Standard Input Format, Source Intermediate Format, Source Interchange Format. The resolution provided by SIF for NTSC video is 352 x 240 and for PAL it is 352 x 288 pixels. 

Coaxial Cable
Cable commonly used to transmit video signals. It consists of a metalic shield with one or more center conductors which are isolated from each other and the shield. 

Composite Video
Video signal that contains the picture signal, and vertical and horizontal blanking and sync pulses. 

Compression
The reduction in the volume of digital data for storage or transmission of video images. Popular, effective algorithms used for video compression are JPEG and MPEG.

Constant Bitrate
A setting within MPEG compression whereby the resultant data stream will attempt to maintain a definable data rate. If high levels of change or movement are present then this could cause a reduction in picture quality.

Constant Quality
A setting within MPEG compression whereby the resultant data stream will attempt to maintain a definable level of picture quality, regardless of the amount of change and movement within the scene.

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

Crosstalk
Undesired signal that interferes with a desired signal 

CRT
Cathode Ray Tube. Image display device used in conventional televisions and monitors. These devices are bulkier and have much higher power consumption than Liquid Crystal Display devices.

CS Mount
New standard lens mounting format.

DB (decibel)
The power ratio of two signals. 

Depth of Field
Front to back area in the camera view which is in focus. The better the lighting, the greater the Depth of Field possible. 

Distribution Amplifier
Device used to send a single video input signal to multiple video output devices 

Duplex (Multiplexer)
A multiplexer which allows viewing of multiple "pictures" during recording 

Dwell
Length of time a video switcher holds a camera's "picture" before switching to the next camera's "picture" 

F-Number
Indicates the brightness of the image formed by the lens and controlled by the iris. A smaller f-number means a brighter image. 

f-Stop
Indicates the speed of a lens. The smaller the number, the greater the amount of light that passes through the lens, thus allowing for better low light camera performance. 

Fiber Optics
Flexible glass fibers used to conduct signals. 

Field
One of the two equal parts into which a TV frame is divided. 

Field Frequency
Number of fields transmitted per second in a TV system. The NTSC standard is 60. 

Field of View
The horizontal or vertical picture size at a given distance from a camera to the subject. 

Focal Length
The distance from the centerline of the lens to the camera pick-up device. It determines the size of the image and the angle of the field of view as seen by the camera through the lens. 

Foot Candle (FC)
Unit of measurement of the intensity of light. 1 FC = 10 lux

FPS
Frame Rates per Second.

FPV
First Person View. 

Frame
One complete TV picture. 

Gain
The amplification a system provides to a signal. 

Gen-Lock
Method used to synchronize one or more cameras by external means. Typical methods are composite video, composite sync, and horizontal or vertical sync. 

Ground
Electrical point that is common to either metal chassis, a terminal, or a ground bus. 

Homing
Process of displaying a given camera output on a given monitor 

Horizontal Blanking
Electrical signal produced at the end of each scanning line 

Hum
Electrical disturbance at the power supply frequency or harmonic. 

IA
US standard, 525 TV lines and 60 fields 

Image Intensifier
Electronic device used to provide a brighter output image than the input image. 

Impedance
Opposition to the flow of electrical current. 

Incident Light
Amount of light directly over an object. 

Infra Red (I.R)
Frequency of light, invisible to the human eye, used for covert surveillance and low light camera use. 

Insertion Loss
Signal strength lost due to the insertion of a piece of equipment in the line.

Looping
Term used when a high impedance device is connected in parallel to a video source. 

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 systems cameras to be routed to any of the systems monitors. 

Modulate
To vary the amplitude or frequency of a signal 

Monochrome
Having one color. In CCTV it is Black and White. 

Multiplexer
Device which allows the recording/playback of multiple cameras on a single time lapse recorder with little loss of information. 

Noise
Random electrical energy or interference 

NTSC
National Television Systems Committee. Formulated the standards with the FCC for color television in the U.S. 

PAL (Phase Alternating Line)
PAL is the analog television display standard that is used in Europe and certain other parts of the world. PAL is one of the three major TV standards together with the American National Television Systems Committee(NTSC) color television system and the French Sequential Couleur avec Memoire (SECAM). Whereas NTSC delivers 525 lines of resolution at 60 half-frames per second, PAL delivers 625 lines at 50 half-frames per second. 

Pan
Horizontal camera movement 

Passive
Non powered element of a system 

Peak-to-Peak
Amplitude difference between the most positive and negative points of a signal 

Pinhole lens
Lens with a very small front, easily concealed, for use in covert applications. 

Quad
Device that simultaneously places the pictures from four cameras onto one video monitor 

Resolution
Measure of the ability of a CCTV system, or one of it's components, to produce detail. 

Roll
Result of the loss of vertical sync which causes the picture on a monitor to move up or down.

RPV
Remote Piloted Vehicle.

Saturation (color)
The vividness of a color which is directly related to the amplitude of the chrominance signal. 

Scanning
Horizontal (panning) camera motion.

Sensitivity (pickup device)
The amount of light needed for the pickup device to operate.

Signal to Noise Ratio
Ratio between a useful signal and unwanted noise.

Spot Filter
A small device used to increase the f-stop range of a lens. 

SVHS
High resolution video recording format. 

SYNC
Electronic pulses inserted in a video signal for assembling picture information in the proper position. 

Time Lapse VCR
VCR that can record for extended periods of time on a single video tape by using frequent tape "pausing". The longer the time of recording, the fewer number of "pictures" recorded per second.

UAV
Unmanned Aerial Vehicle.

Vari-focal Lens
Lens with an adjustable focal length, such as 3.5-8mm, 6-15mm, and 6-60mm.

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.

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