GB1280278A - Tdm telephone exchange - Google Patents

Abstract

1280278 Reducing cross-talk in multiplex communication systems; multiplex pulse signalling INTERNATIONAL STANDARD ELECTRIC CORP 19 April 1971 [26 Jan 1970] 20169/71 Headings H4K and H4L A time division multiplex communication system with GO and RETURN highways reduces cross-talk between channels by terminat - ing each highway at one end with an amplifier showing low impedance to the highway and by terminating the other end of each highway with its characteristic impedance. As shown in Fig. 4 subscribers T are connected from one side of a hybrid G to a GO highway by means of gates S 1 to Sk. Highway pulses are passed on over a low impedance amplifier V terminating one end of the highway. For a GO highway V may be a transistor in common base configuration. For a RETURN highway V may be a transistor in emitter-follower configuration. The ends of the highways remote from amplifiers V are terminated with the characteristic impedance which absorbs any reflections from low impedance termination of V. Between time channel switching periods the ends of the highways connected to amplifiers V may be switched to the characteristic impedance as a termination in order to promote discharge of the highway.