Method of and circuit arrangement for picture transmission using multiplex techniques

Claim 1

A circuit arrangement for transmitting pictures in both directions over a single transmission line from a first station to a second using time-division multiplex techniques, comprising: means at the receiving end for displaying and storing a partial received image, and means for controlling a secondary display of said image during transmission in the opposite direction, and recivers and transmitters at each end of the transmission line, a double-throw switch for connecting said receivers and transmitters to said transmission line, wherein the video signal of a complete or partial picture have different clock-pulses at its leading and trailing edges, said double-throw switches being responsive to said clock pulses to automatically switch the transmitters and receivers into the respective transmitting and receiving positions and wherein there are discriminators associated with the double-throw switches at the inlet on a line side and the outlet on a transmitter side, which discriminators respond to the clock-pulses of the video signal, a first of said discriminators at the outlet on the transmitter side of the double-throw switch causing the switch to assume the transmitting position on receiving the leading edge of the video signal and to assume the receiving position on receiving the trailing edge of the video signal, and a second of said discriminators at the inlet on the line side of the double-throw signal causing the switch to assume the receiving position on receiving the leading edge of the video signal and to assume the transmitting position on receiving the trailing edge of the video signal.