Closed Circuit Television (CCTV) is the use of video cameras to transmit signal to a specific, limited set of monitors. It differs from broadcast television in that the signal is not openly transmitted, though it may employ point to point wireless links. CCTV is often used for surveillance in areas which need monitoring, such as banks, casinos, airports, military installations and convenience stores. Increasing use of CCTV in public places has caused debate over public surveillance versus privacy. In industrial plants, CCTV equipment may be used to observe parts of a process that are remote from a control room, or where the environment is not comfortable for humans. CCTV systems may operate continuously or only as required to monitor a particular event.
The first CCTV system was installed by Siemens AG at Test Stand VII in Peenemünde Germany in 1942, for observing the launch of V2-rockets. The noted German engineer Walter Bruch was responsible for the design and installation of the system. CCTV recording systems are often used at launch sites to record the flight of the rockets, in order to find the possible causes of malfunctions. Film cameras are also used for this purpose. Larger rockets are often fitted with CCTV allowing pictures of stage separation to be transmitted back to earth by radio link. CCTV is also used to observe the launch pad before the launch, especially when no person may be there because of safety reasons.
A CCTV system may be installed where an operator of a machine cannot directly observe people who may be injured by unexpected machine operation. For example, on a subway train, CCTV cameras may allow the operator to confirm that people are clear of doors before closing them and starting the train. Operators of an amusement park ride may use a CCTV system to observe that people are not endangered by starting the ride. A CCTV camera and dashboard monitor can make reversing a vehicle safer, if it allows the driver to observe objects or people not otherwise visible.