Simply speaking, Closed-circuit television (Cctv) is the use of video cameras to forward a signal to a specific, miniature set of monitors. It differs from broadcast television in that the signal is not openly transmitted over the social air waves. Usually a terminated circuit television (Cctv) principles uses a stand-mounted or hand-held video camera to scheme a magnified image onto a video monitor or a television (Tv) screen. Cctv systems may operate continuously or only as required to monitor a singular event.
The technology of terminated circuit television (Cctv) originated in the 1950s and consisted of two low-resolution black and white cameras. Its main objective was to replace humans for visual protection surveillance. In the 1980s, solid state cameras and Vcrs were introduced. The resolution was better, but the pictures were still in black and white. In the 1990s, came the transformation to color, and ultimately digital video recorders (Dvrs) were introduced. Today there are still applications where black & white cameras are used, because they achieve much best in low light and Ir illuminated applications than the color cameras. And cameras are getting smaller and smaller. miniature protection cameras can today be installed virtually everywhere (such cameras can even consist of infra-red illumination which enables us to see in the dark).
Traditional video transmission in Cctv is done using 75 ohm coaxial cables. The video signal transmitted is a normal composite video signal, although some systems use Radio Frequency signals. The camera is Usually powered by low voltage (typically 12V or 24V) through a local power supply near the camera or a cut off power cable fed together with the coaxial cable. There are also some systems which feed the power to the camera through the same coaxial cable where to photograph is transported.
Some of the more popular applications for Cctv surveillance are:
Retail
- monitoring for shoplifters and dishonest employees
- compiling recorded evidence against bogus emergency claims
- monitoring merchandising displays in shop hundreds of miles away
Manufacturers, Banks, Casinos, Hospitals and Universities
- identifying visitors and employees
- thwarting theft
- ensuring the protection of the premises and parking facilities
Airports and military Installations
- watching for potential high-jackers, and terrorists
Industrial Plants
- observing procedures that are remote from a operate room
- monitoring dangerous work areas
Sports Venues
- providing fans in the "cheaper" seats a best view of the action.
Home protection
- watching for unwanted visitors with video intercom doorbells
- observing child/elder caretakers with nanny cams
In summary, advances in Cctv technology are turning video surveillance into one of the most vital loss prevention, safety/security and supervision tools ready today.
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