Patent GB-715006-A (GB)
Title: Improvements in or relating to electric pulse multi-channel signal transmission system
IPC: H04B7/17
Filed: 1952-12-18
Abstract: 715,006. Multiplex pulse signalling. TELEFUNKEN GES. FUER DRAHTLOSE TELEGRAPHIE. Dec. 18, 1952 [Dec. 22, 1951], No. 32156/52. Class 40 (5) Relates to radio systems using a multiplex pulse train between two main stations, linked by at least one relay station, at which demodulated pulses remodulate a fresh carrier and which is supplied with pulses from a branch station to be inserted into the composite pulse train. Synchronization of the branch channels is effected in one arrangement by modulating one of the main channels by a signal derived by frequency division from the channel pulse recurrence frequency and demodulating and frequency multiplying this signal at the branch station to provide the master frequency thereat. In another arrangement, synchronizing pulses from the transmitter at one main station control the branch station after passing to the other main station and being retransmitted therefrom. In one embodiment, which provides two-way communication between one main station A of the pair A, B, Fig. 2, and the branch station C, all three are linked by a relay station R, at which a frequency divider FT is provided to which are fed the synchronizing pulses from the transmitter So, station B, received and demodulated in receiver E. The frequency, reduced in the ratio one third, is. used to modulate one of the free channels, in modulator M, and transmitted to the receiver E1 at station C. After demodulation, it is fed to the frequency multiplier FV the output of which feeds the pulse unit of transmitter S1. The pulse phase is corrected by a phase shifter Q the control of which is effected automatically by a phase comparison at station R of the synchronizing pulse phase in the main and branch directions. The correcting voltage, produced in stage RS, is transmitted over one of the channels to station C, where it is recovered in circuit RU and controls a motor Mo which adjusts the phase shifter Q. The pulse stages Z of the relay station R produce gating, voltages necessary for removing pulse channels,: in stages a and inserting pulse channels in stages e. This arrangement is duplicated to provide two-way communication between both stations A and B and the branch station C, two: radio frequencies also being necessary, but these may use common aerial systems, Fig 4 (not: shown). An alternative embodiment providing two-way communication between a branch station C, and one main station A is shown in Fig. 5, the references in which correspond where present with those in Fig. 2. The synchronizing pulses from transmitter So, station B, are selected by circuit Sy1, station A, and control the pulse recurrence frequency at the transmitter So of station A, after conversion to sine-wave form. A corresponding synchronizing device Sy2 is fed from receiver E1 of the station C and controls transmitter S1 through the phase shifter Q; the automatic phase control being the same as in Fig. 2. For mtercommunication between all three stations delay devices are provided at the relay station to ensure correct interlacing of added channels in both directions, Fig. 6 (not shown).