CCTV (closed-circuit television) cameras are used in department stores and car parks, and on highways and city streets; many people are also installing them in their homes. People who live in London are videotaped an average of 80,000 times each year.
Closed-circuit cameras refer to cameras that are hard-wired, as opposed to being transmitted like a TV station broadcast. CCTV cameras use a coaxial cable to send the signal to a security DVR or computer.
CCTV cameras come in a variety of types, each used for a specific purpose. There are stationary cameras, cameras which can move, cameras which can see in total darkness, cameras that can zoom and cameras that can track motion.
PTZ (pan-tilt-zoom) cameras can be moved from side to side (panning), moved up and down (tilting) and zoomed to see a number plate from hundreds of yards away.
IR (infrared) cameras can see in total darkness. They use a group of IR LEDs (light-emitting diodes) to illuminate their field of view. IR is just outside the range of light that humans can see, but IR cameras can use this light to display a black and white picture.
Motion tracking cameras can detect motion and track and record the moving object.
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