Multiplexed audio-video signal transmission system through pair-wire.

摘要

A multiplexed audio-video signal transmission system has a camera-equipped intercom (1, 2, 3) which produces a balanced audio-video signal. A twisted pair-wire connected to the intercom transmits a multiplexed signal of audio signal, video signal modulated to a frequency band not overlapping the audio signal frequency, and DC power. The audio signal and video signal are carried in the pair-wire in opposite phase in a balanced condition, and the DC power is carried between the pair-wire. A relay device (4) is inserted in the pair-wire to refine the video signal. Main line branching device (7) and door branching device (13) are provided to branch out the multiplexed signal to a television equipped control unit 17. <IMAGE>