GB1294732A - Multiplexing of binary signals - Google Patents

Abstract

1294732 Digital TDM systems CIT COMPAGNIE INDUSTRIELLE DES TELECOMMUNICATIONS 13 May 1970 [14 May 1969] 23196/70 Heading H4P In an apparatus for encoding binary signals such as is disclosed in Specification 1,294,731 the output of a plurality of coders is time division multiplexed on to a plurality of sub bands such that at least one channel operating at a slow speed S occupies one sub band, and at least one other channel operating at a speed nS, where n is an integer, occupies n sub bands. One sub channel, e.g. the first may be used as a synchronizing channel for decoding. Fig. 1 illustrates a system of 32 sub bands which may be utilized in conventional manner by 32 channels each 50 baud, or according to the invention in a multi speed system the bands may be distributed proportional to the speed i.e. 8 x 50bd, 2 x 200bd and 1 x 100bd, the faster channels utilizing more sub bands proportional to the speed i.e. the 800bd system occupying 16 sub bands. The sub bands are preferably evenly distributed so that for example the 800bd band uses all the odd numbered sub bands. Gray code may be used for synchronizing coded signals as described in connection with the prior Specification, and signals are converted to this code (at T1, Fig. 3, not shown) after multiplexing at (X). A corresponding Gray code converter (T2) is used as a receiver. Signals are sampled at a rate (F1 &c.) proportional to incoming speed.