GB1238657A - - Google Patents

Abstract

1,238,657. Multiplex pulse code signalling. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. 12 June, 1968 [30 April, 1968], No. 28031/68. Heading H4L. In a mutiplex system a plurality of signals each having two discrete levels are combined into a single multilevel signal for transmission. Transmitter, Fig. 1.-Facsimile signals I, II are supplied via amplifiers 3, 4 to wave shapers 5, 6 providing signals S1, S2, Fig. 3, which are supplied to a code conversion circuit 7. The facsimile signals are included with a predetermined bandwidth W and are sampled at 7 by pulses S7 from generator 12 having an interval 1/2W to produce pulses S3, S4, S5 corresponding respectively to the combinations 11, 10 and 01 of the input signals. These pulses are supplied via delay circuits 9, 10, 11 and also directly to a code synthesizer 8 where they are combined to form a four-level signal S6 representing the four possible combinations. The delay circuits are arranged to introduce reflections which are of opposite phase to those introduced in the transmission link so that the signals are received with a minimum of distortion, Figs. 10 to 15 (not shown). Pulses S6 are supplied to a low pass filter 14, having a cut-off frequency W, providing signal S8 which modulates at 16 a carrier from generator 17 for transmission. Receiver, Fig. 2.-Incoming signals are demodulated at 29 and supplied via filter 30 (signal S8) to level comparators 31, 32, 33 controlled by sampling pulses from generator 34 synchronized with the sampling pulses at the transmitter. The resulting signals S9, S10, S11 corresponding to S3, S4, S5, are fed to a code conversion circuit 35 operating in an inverse manner to circuit 7 at the transmitter to provide output signals S12, S13 corresponding to the original signals S1 S2. Modifications. The method of coding three input signals is described. A system for adjusting the timing of the sampling pulses at the receiver also is described, Fig. 16 (not shown).