CCTV Systems Control
While the majority of cameras are installed in a fixed position, in order for the operator to be able to follow an incident it can be very useful to have the facility to pan, tilt and zoom the camera.
This is achieved by the use of a mechanical pan and tilt head on which the camera is mounted and a zoom lens which are controlled remotely by telemetry signals. As in most instances the camera will be fitted outdoors and therefore it will be necessary to use a housing which will protect it from the elements or to use a dome camera.
Telemetry
There are two types of electronic telemetry: one uses a twisted pair, where long distances are involved; the second uses coaxial cable – in fact, the same cable that carries the video signal. The basic form of telemetry control system uses digital techniques to produce a pulse code modulated (PCM) signal. This is a signal which has a series of 16 pulses and, depending upon the function required (pan/tilt or zoom), sends the appropriate pulses to a receiver which interprets them and carries out the function.
Housings and Enclosures
These protect the CCTV camera/lens assembly. Used in both internal and external applications, housings also protect against dust, vandalism and extreme weather conditions.
Many different housings are available with accessories, such as thermostatically controlled viewing windows, sunshields, blowers for hot environments and heaters for use in extreme cold.
Domes
Domes operate in much the same way as a conventional pan, tilt and zoom camera except that they are generally more compact and have the added advantage of being discreet – both aesthetically and for the purpose of surveillance. It is not usually possible to see in which direction the camera within the dome is directed.
Conventional housings score over domes in terms of robustness and there is less chance of the optical distortion created by the spherical dome cover.
For more information contact the Sony Business Information Centre: 01932 816340
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