GB596051A - Improvements in or relating to electrical pulse communication systems - Google Patents

Abstract

596,051. Multiplex pulse signalling. STANDARD TELEPHONES & CABLES, Ltd. July 16, 1945, No. 18204. Convention date, May 19, 1944. [Class 40 (v)] A communication system including a plurality of stations uses time-modulated pulses between two of the stations, which pass through a third station, and amplitude modulation of the timemodulated pulses is used for communication between the third station and one of the other two. The system may be further multiplexed by the intercalation of several time-modulated channel trains of pulses. In one embodiment, for a single time-modulated channel, a relay and " in and out" branching unit is designed to receive pulses 17, Fig. 2, having both time and amplitude modulation. A decoupling amplifier 18 and low-pass filter 19 yield the wave 21 with which pulses 17 are amplitude modulated. A clipper-amplifier 22 inverts and removes the amplitude modulation from pulses 17 to yield time-modulated pulses 24. If switches 25, 29 are open and switch 35 closed, the pulses 24 are passed to valve 36 where they are further amplitude modulated with a signal 37 from source 38 and pass out of the station as pulses 39. Alternatively, with switch 35 open, and switches 25, 29 closed, the pulses 24 are demodulated at 26 and,fed through low-pass filter 27 to a reproducing device 28. Further time-modulated pulses 30 are produced in modulator 31 fed from a signal source 32 and a wave generator 34 synchronized by pulses 24. The new pulses 30 are fed over switch 29 to valve 36 for amplitude modulation as before. A multi-channel unit is also described, wherein intercalated time and amplitude-modulated pulse trains are received from a radio receiver 53, Fig. 3, or line 51, the pulses of one channel train being of greater duration than those of the others to serve as synchronizing pulses. Gating pulses for the three channels shown are derived from clipper 57, synchronizing channel pulse duration discriminator 58, gating pulse shaper 59 and individual phase-shifters 60, 61, 62 adjusted to pass the gating pulses to channel separators 63, 64, 65, respectively, with the correct phase. Relay units 71, 72, 73, respectively, of the type shown in Fig. 2 are connected to the outputs of units 63, 64, 65 and their outputs are fed to a mixer 74 feeding the outgoing line 75 or radio transmitter 76.