GB679267A - Improvements in and relating to multi-channel pulse signalling systems - Google Patents

Abstract

679,267. Multiplex pulse signalling. GENERAL ELECTRIC CO., Ltd. Nov. 24, 1950 [Nov. 21, 1949], No. 29745/49. Class 40 (v). In a pulse time-division multiplex signalling system with n interlaced channels, (n - - r) channels are dropped by providing a gating circuit, the gating pulses for which are derived from the synchronizing pulses and have a recurrence frequency of r times the channel recurrence frequency and a duration equal approximately to one channel interval, n/r being an integer. In the embodiment described, a radio repeater station is adapted to receive and transmit all 36 channels of the system from and to a station A<SP>1</SP> and to communicate with two other stations B<SP>1</SP> and Clover 24 channels and the remaining 12 channels respectively. The incoming wave from station A<SP>1</SP>, received on the common transmitting and receiving aerial A, provides at the output of the receiver 10 ... 15, the 36-channel multiplex pulse train which is fed in parallel to two gate circuits 16, 17 and a synchronizing signal separator 18. From the synchronizing pulse train, the twelfth harmonic of the recurrence frequency is selected in circuit 19 and used to produce, in the waveform generator 20, oscillations of rectangular waveform in which the positive-going portions have half the duration of the negative-going portions. This wave is applied to the gate circuit 16 after appropriate phasing to select, for example, the pulses of channels 1, 4, 7, &c., which modulate radio transmitter 21, 22, 23, connected to aerial B, communicating with station B<SP>1</SP>. The remaining channel pulses are selected in gate circuit 17, by applying thereto the same waveform, but in opposite sense, and modulate the transmitter 24, 25, 26 connected to aerial C, communicating with station C'. The channel pulses received on aerials B and C are applied to the mixer 28 of radio receiver 28.... 33, or to separate mixers whose outputs are combined, and the resultant complete multiplex pulse train is retransmitted by transmitter 34, 35, 36 from aerial A to station A<SP>1</SP>.