CCTV Glossary
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.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.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.
Auto Pan
Automatic back and forth camera motion
Auto Scan
Same as Auto Pan
Auto Iris Lens
Camera lens which automatically adjust for proper light levelsBandpass
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
Blooming
Defocusing effect that occurs around bright areas of a picture when an increase in brightness occurs.
BNC
Most commonly used video cable connector.Bridging
When a high impedance video line is paralleled, usually through a
switch, to a source of video.C-Mount
Former industrial standard lens mounting formatCandlepower
Unit measure of incident light
CCD (Charged Coupled Device)
The "chip" in a solid state camera that replaced the camera tube .
CCTV
Closed Circuit Television
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
Reduction in gain at one level of a video signal with respect to the gain at another level of the same signal
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
CS Mount
New standard lens mounting formatDB (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.
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"
Distribution Amplifier
Device used to send a single video input signal to multiple video output devicesF-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
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.Infra Red (I.R)
Frequency of light, invisible to the human eye, used for covert surveillance and low light camera use.
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.
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 FCMatrix 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.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 monitorResolution
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 downSaturation (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.Vari-focal Lens
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 scanZoom Lens
A lens that is used as a wide angle, standard, or telephoto lens by varying the lens focal length