GB1446333A - Multiplex communication system - Google Patents

Abstract

1446333 Multiplex PCM systems POST OFFICE 22 July 1974 [8 May 1973] 21905/73 Heading H4L In a time division multiplex communication system for a plurality of multidigit channels, alternative multiplex signal structures may be used, a first structure having a frame comprising channels with a first number of digits and a second structure having a frame comprising channels with a second greater number of digits, means being provided for enabling in one structure an adjustable plurality of the channels of that structure to be replaced by a plurality of channels of the other structure. As described the first multiplex structure has a frame consisting of thirty information channels of eight digits each and two signalling channels of eight digits and the second multiplex structure has a frame consisting of thirty-two information channels each of ten digits with a signalling channel of eight digits for every twelve channels of ten digits, a four frame multiframe of the first structure being of the same duration as a three frame multiframe of the second structure. The said means includes a first shift register having stages corresponding to channels of the first structure, a second shift register having stages corresponding to channels of the second structure and a pulse generator for shifting a digit along each register in correspondence with the channels and digits of a multiplex signal in the system, signals being derivable from the registers as required to control the insertion of channels of the first and second structures respectively into a desired multiplex signal.