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CCTV & Video Surveillance Glossary
Auto electronic shutter (AES). Feature of a camera to adjust for light changes without the use of an auto-iris lens.
Auto iris. A special camera lens with the ability to open or close its iris automatically in response to changing light levels.
Back-light compensation (BLC). The ability of a digital security camera to adjust for bright background lighting that would normally cause the subject to appear too dark.
C-mount. A type of camera lens mount that enables different lenses to be swapped out and used on a security camera.
CCD. The light-sensitive imaging microchip found in digital security cameras.
Digital video recorder (DVR). A special computer that converts analog computer images to digital images, compresses the images, and then stores them for later viewing. A DVR replaces the time-lapse VCR, multiplexor and switch found in analog CCTV surveillance systems.
Duplex. An electronic device used to record and display camera images at the same time. A full-duplex DVR can record camera images while displaying images from a different camera at the same time.
Housing. Protective enclosure that a camera can be placed in to protect it from outside weather conditions.
Lux. Unit of measure of light sensitivity for a camera. Sensitive cameras can operate with low levels of lux.
Multiplexer. An analog device found in older CCTV systems that allows multiple cameras to be displayed simultaneously on a single monitor. Multiplexers can also be used to transmit multiple camera images at once over a single cable.
Pinhole camera. A spy camera with a lens that can see through a tiny hole. These camera are usually hidden.
Power-over-Ethernet (POE). Device that allows one to transmit power to a security power through an Ethernet network cable.
PTZ. Stands for pan-tilt-zoom. PTZ cameras have motors that allow them to be remotely moved up-down, side-to-side, and the camera lens zoomed in or out.
Quad. Analog CCTV equipment used to display 4 camera images simultaneously on a single monitor.
Real-time recording. For digital video, 30 frames-per-second per camera allows no jerkiness in the video.
Remote surveillance. The ability to view a camera image that is located remotely, where the video image is transmitted over a phone line or the Internet.
RG-59. A type of coaxial cable used in CCTV systems.
Signal-to-Noise Ratio (SNR). The ratio of video signal to noise. This is a measure of how much signal noise the camera can withstand and still present a good image. The higher this number is, the better the picture quality.
Switch. An analog device found in older CCTV systems that takes multiple camera inputs and displays them on a monitor one at a time (unlike a quad).
Time-lapse VCR. A special VCR found in analog CCTV systems designed to slow down the recording rate in order to store many hours of video footage on a single videotape.
Varifocal lens. A camera lens in which the focus is not fixed and that can be adjusted either manually or automatically.
Video gain. Also called video amplification, this is the increase in video signal power by an amplifier.
Watch-dog timer. The automatic reboot of a DVR system whenever a problem is detected.
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