CCTV Systems consist of digital processed cameras that can be hard wired or wirelessly linked back to a DVR (Digital Video Recorder). The DVD hard drive allows constant recording for periods of many hours/days, depending on the quality required. Once the hard drives have reached their capacity they will record over the first recordings. Most DVR’s have extra features such as motion-detection, alarm inputs and email alerts also allow the viewing of the CCTV images over the internet via a computer, smart phones and iPads.
The CCTV cameras can be mono (black and white) or colour. Day night CCTV cameras are during the day colour and at night they change to black and white, giving a better viewing quality.
WDR (Wide Dynamic Range) cameras can be used when the sun or bright light is behind the target image in a door entrance or window. PTZ (Pan Tilt & Zoom) cameras are used in situations where there is a large area to cover or where the cameras are being controlled by security guards supermarkets and street CCTV cameras. These cameras can be controlled by the person with a joystick or via the software over the internet.
Infra red lights are used to allow the viewing of areas at night when there is insufficient light for the CCTV camera. CCTV monitors now use LCD screens allowing them to be wall mounted. IP (Internet Protocol) CCTV cameras are now being used. They can be equipped with megapixel sensors, and they support recording directly to network-attached storage devices or internal flash (SD Card) for a completely stand-alone operation.