CCTV (closed-circuit television) is a TV system in which signals are not publicly distributed but are monitored, primarily for surveillance and security purposes.
CCTV relies on strategic placement of cameras and private observation of the camera’s input on monitors. The system is called “closed-circuit” because the cameras, monitors and/or video recorders communicate across a proprietary coaxial cable run or wireless communication link. Access to data transmissions is limited by design.
In the past, CCTV systems used small, low-resolution black and white monitors with no interactive capabilities. Modern CCTV displays can be high-resolution color, providing the CCTV administrator with the ability to zoom in on an image or track something (or someone). Talk CCTV allows the administrator to speak to people within range of the camera’s associated speakers.
CCTV is commonly used for a variety of purposes, including:
- Maintaining perimeter security.
- Monitoring traffic.
- Obtaining a visual record of human activity.
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, utilizing 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, some equipped with megapixel sensors, support recording directly to network attached storage devices, or internal flash for completely stand-alone operation. Surveillance of the public using CCTV is particularly common in many areas around the world.