Ohnsorge, H.H.Ohnsorge2022-03-082022-03-081977https://publica.fraunhofer.de/handle/publica/301599DE 2538638 C UPAB: 19930901 The communications network using fibre-optic transmission lines uses one glass-fibre conductor for each of the send and receive paths. A subscriber video camera and analog-digital converter output is transmitted using 4-bit DPCM at 48 Mbit/s for black and white, 64 Mbit/s is used for the speech channel. The video and speech signals are switched to the light-emitting diode or laser transmitter. At the exchange the video and speech signals are separated and pass through digital-analog converters, the speech being routed through the usual telephone coupling circuits and the video information routed to a special television distribution network.de608621patent1975-2538638