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Glossary of CCTV Terms (Page 4)
- NOlSE - Random spurts of electrical energy or interference.
- NTSC - National Television Systems Committee that worked with the FCC in formulating the standards for the United States color television system.
- PASSlVE - A non powered element of a system.
- PEAK-TO-PEAK - The amplitude difference between the most positive and the most negative excursions of a signal.
- PlNHOLE LENS - Lens used for applications where the camera/lens must be hidden. Front of lens has a small opening to allow the lens to view an entire room through a small hole in a wall.
- POWER - The rate at which electrical energy is applied to or taken from a device. It is expressed in terms of watts, milliwatts or microwatts.
- PRE-POSITION LENSES - Zoom lenses which utilize a variable-resistor (potentiometer) to indicate zoom/focus position to the lens controller. After initial set-up, this allows the operator to view different pre-set areas quickly without having to re-adjust the zoom and focus each time.
- RANDOM lNTERLACE - A scanning technique commonly used in CCTV systems in which there is no external control over the scanning process. That is, there is no fixed relationship between adjacent lines and successive fields.
- RANGE FlNDER Used to determine the focal length needed and what the picture will look like on the monitor. The user looks through the device and adjusts the range finder to the desired picture. Numbers on the outside of the range finder indicate the focal length needed. RASTER The rectangular pattern of scanning lines upon which the picture is produced. The illuminated face of the TV monitor without the video information present.
- REFLECTED LlGHT - The scene brightness or the light being reflected from a scene. Usually it represents 5 to 95 percent of the incident light, and it is express~d in foot-lamberts.
- RESOLUTlON A measure of the ability of a camera or television system to reproduce detail. That is the number of picture elements that can be reproduced with good definition. It is a factor of the pickup device or the TV CRT characteristics and the video signal bandwidth.
- RETAlNED lMAGE (IMAGE BURN) - A change produced in or on the target of the pickup device which remains for a large number of frames after the removal of a previously stationary light image and which yields a spurious electrical signal that corresponds to that light image.
- RADlO FREQUENCY (R.F.) - Signals with a repetition rate above audible range, but below the frequencies associated 4 With heat and light.
- ROLL - A loss of vertical sync which causes the picture to move up or down on the TV screen.
- SATURATlON (COLOR) - The vivi
dness of a color. It is directly related to the amplitude of the chrominance signal. SCANNlNG - The rapid movement of the election beam in a pickup device of a camera or in the CRT of a television receiver. It is formatted in a line-for-line manner across the photo sensitive surface which produces or reproduces the video picture. When referred to a video surveillance field, it is the panning or the horizontal camera motion.
- SENSlTlVlTY (PICKUP DEVICE) - The amount of current developed per unit of incident light. It can be measured in watts with the projection of an unfiltered incandescent source of light at 2870 K degrees to the pickup device surface area. It can be then expressed in footcandles.
- SlGNAL TO NOlSE RATlO - The ratio between a useful video signal and unwanted noise.
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