Closed-circuit television (CCTV), also known as , is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly transmitted, though it may employ point-to-point (P2P), point-to-multipoint (P2MP), or mesh wired or wireless links. Even though almost all video cameras fit this definition, the term is most often applied to those used for surveillance in areas that require additional security or ongoing monitoring (Videotelephony is seldom called "CCTV".
Surveillance of the public using CCTV is common in many areas around the world. In recent years, the use of body worn cctv in singapore has been introduced as a new form of surveillance, often used in law enforcement, with cameras located on a police officer`s chest or head. Video surveillance has generated significant debate about balancing its use with individuals' right to privacy even when in public.
In industrial plants, CCTV equipment may be used to observe parts of a process from a central control room. For example, when the environment is not suitable for humans. CCTV systems may operate continuously or only as required to monitor a particular event. A more advanced form of CCTV, using digital video recorders (DVRs), provides recording for possibly many years, with a variety of quality and performance options and extra features (such as motion detection and email alerts).
More recently, decentralized IP cameras, perhaps equipped with megapixel sensors, support recording directly to network-attached storage devices, or internal flash for completely stand-alone operation.
By one estimate, there will be approximately 1 billion surveillance cameras in use worldwide by 2021.[needs update] About 65% of these cameras are installed in Asia. The growth of CCTV has been slowing in recent years. The deployment of this technology has facilitated significant growth in state surveillance, a substantial rise in the methods of advanced social monitoring and control, and a host of crime prevention measures throughout the world.
An early mechanical CCTV system was developed in June 1927 by Russian physicist Léon Theremin (cf. Television in the Soviet Union). Originally requested by the Soviet of Labor and Defense, the system consisted of a manually-operated scanning-transmitting camera and wireless shortwave transmitter and receiver, with a resolution of a hundred lines.
Having been commandeered by Kliment Voroshilov, Theremin's CCTV system was demonstrated to Joseph Stalin, Semyon Budyonny, and Sergo Ordzhonikidze, and subsequently installed in the courtyard of the Moscow Kremlin to monitor approaching visitors.
Another early CCTV system was installed by Siemens AG at Test Stand VII in Peenemünde, Nazi Germany in 1942, for observing the launch of V-2 rockets.
In the U.S. the first commercial closed-circuit television system became available in 1949, called Vericon. Very little is known about Vericon except it was advertised as not requiring a government permit. Find More