digital video recorder surveillance

CCTV cameras can produce images or recordings for surveillance purposes, and can be either video cameras, or digital stills cameras.

Video cameras

Video cameras are either analogue or digital, which means that they work on the basis of sending analogue or digital signals to a storage device such as a video tape recorder or PC/laptop.

Analogue video cameras

Can record straight to a video tape recorder which are able to record analogue signals as pictures, but these devices are becoming obsolete as more cameras are being manufactured as digital devices.

If the analogue signals are recorded to tape, then the tape must run at a very slow speed in order to operate continuously. Products include wireless accessories, keypads, window contacts, and more. This is because in order to allow a 3 hour tape to run for 24 hours, it must be set to run on a time lapse basis which is usually about 4 frames a second. In one second, the camera scene can change dramatically. A person for example can have walked a distance of 1 meter, and therefore if the distance is divided into 4 parts ie 4 frames or 'snapshots' in time, then each frame invariably looks like a blur, unless the subject keeps perfectly still.

Analogue signals can also be converted into a digital signal to enable the recordings to be stored on a PC as digital recordings.