An electronic system that can accept a number of camera inputs and record them virtually simultaneously. They can also provide multiscreen displays with four, nine, sixteen etc. cameras on the screen at once. Multiplexers can be used to transmit multiple pictures down a single video line whether it is a coaxial cable, microwave, infrared link etc. This requires a multiplexer at each end of the line.
A Multiplexer combines multiple video inputs into a single feed for display or recording, used in analog systems.