Closed-Circuit Television (CCTV) is currently used in a wide scale. Compared to television broadcast, CCTV is not distributed to the public. CCTV systems include video cameras, monitors and transmission networks, and the technology can be wired or wireless. CCTV is used for:
Camera systems (WebCams) mostly work continuously. Modern CCTV uses advanced forms of digital storages for the recorded data.
The first closed-circuit television was commissioned by Siemens in 1942. The cameras for monitoring were placed in the testing facility of the German V-2 rocket site at Peenemünde, Germany. The design of this circuit was proposed by a German engineer Walter Bruch, who was also responsible for its installation. The US built their first CCTV called “Vericon” in 1949.
Early CCTV systems used fixed monitors, because it was not possible to record and store the information. Further development allowed recording on magnetic tapes, which had to be manually changed when the tape was full. The operation of such system was unreliable and expensive. In 1970, VCR (Video Cassette Recorder) technology enabled easier and more affordable recording and further manipulation. Another big step was possible after the introduction of digital multiplexing in 1990, which allowed recording of multiple camera inputs at once, saving time and money and resulting in extended use of CCTV. The current technology has been further developed to use Internet-based products and systems.
Currently, the technology of wireless IP cameras connected to a local area network (LAN) is used quite often. Internet protocol can transfer recordings from video servers over a public network to any computers or mobile device worldwide.