May 18th 2008
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Glossary
Below are a few technical terms which are frequently used with CCTV Cameras and products. This is part 1 and will publish few more in the future parts.
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AGC - Automatic Gain Control - Electronic Circuit to increase the video signal in low light conditions. This usually introduces noise into the picture and should be Off unless required.
Aperture - The light gathering area of a lens, the iris controls the size of the aperture.
Aspect Ratio - The ratio of the vertical to the horizontal image size. eg : 3:4
Automatic IRIS - A lens that automatically adjusts to allow the correct amount of light to fall on the imaging device. The tiny motor and amplifier built in generally receives a control signal from the camera to maintain a constant one volt peak to peak (PP) video level.
Back Focus - A mechanical adjustment in camera that moves the imaging device relative to the lens to compensate for different back focal lengths of lenses. This is very important for a zoom lens fitted camera.
Balanced Signal - A video signal converted to a balanced signal, usually to enable it to be transmitted along a twisted pair cable. Used in situations where the cabling distance is too great and which would produce unacceptable losses in coaxial cable.
Bandwidth - The amount of space in a given part of a spectrum needed to carry communication signals.
Bifurcator - An adapter with which a loose tube containing two optical fibres can be split into two single fibre cables.
Black Level - The dark parts of a video signal corresponding to approximately 0.3 volts.
Blanking Period - The period of the composite video at black level and below when the retrace occurs, making it invisible on the screen.
Buffer - The material surrounding the fibre to protect it from physical damage.
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