Sony ISSUE 3 manual What is Closed Circuit Television?

What is Closed Circuit Television?

Closed Circuit Television (CCTV) is a television system which operates on a ‘closed loop’ basis. Unlike broadcast television, which is available to anyone with a suitable receiver, CCTV pictures are only available to those directly connected to the loop.

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Colour Video Monitor

Video Out (Coaxial cable)

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CCTV was first used in the 1950s and has since become an essential element in any professional security system.

In most installations, the loop is a physical link – a cable which carries the picture from the camera to the viewer. With very few exceptions, the pictures are transmitted as a composite video signal at 75ohms, 1 volt peak-to-peak. Where very high resolution (>400TV lines) is required, some equipment offers a Y/C facility where the luminance signal (Y) and the chrominance (C) is divided. Over long distances, for example in Town Centre systems, fibre optic transmission has become popular. Where this option is too expensive, ISDN offers a cost-effective alternative for event-driven surveillance systems.

As well as the full range of property protection and control applications, CCTV offers benefits in many other areas, for example:

■Assisting police authorities in the monitoring of traffic flow and the implementation of prompt action in case of accidents and other emergencies

■Supporting process industry managers as they control the flow of work, identify production bottlenecks and take corrective action

■Monitoring of hostile environments that are not accessible to man, i.e. nuclear reactors, furnaces, etc.

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The Sony Guide to CCTV . Issue 3