GB655749A - Pulse time multiplex communication system - Google Patents

Abstract

655,749. Multiplex pulse signalling; pulse circuits. BENDIX AVIATION CORPORATION. Nov. 4, 1948, No. 28687. Convention date, Dec. 31, 1947. [Classes 40 (v) and 40 (vi)] The multiplex pulse train in a communication system comprises groups of pulses, the first of which is a reference pulse, the second of which is time displaced from the first in dependence upon a first channel signal, the third from the second in dependence upon a second channel signal and so on, the first reference pulse being displaced from the last pulse of the preceding group in dependence upon the last channel signal. In the embodiment described, each element of a chain of flip-flop multivibrators 10 is triggered to its unstable state by the reversion of the preceding one to its stable state. The period for which each circuit remains in the unstable state is determined by the signal voltage applied through transformer 20 to the grid of the normally conducting valve 17. The positive output pulse at the anode of valve 16 when it reverts to its non-conducting condition is fed to the grid of the corresponding valve in the next circuit 10 and to a signal pulse generator 11. In order to start the cyclic operation of the chain, a blocking oscillator 21 is provided which is normally inhibited by the negative charge on the grid condenser 23 maintained by pulses from one of the multivibrators fed through diode 25 and condenser 27. On starting up, or failure of the chain, the valve 21 produces a triggering pulse which is applied through transformer 22 to the cathode of valve 16 of one of the multivibrators. The signal pulse generators 11 comprise blocking oscillators 30, producing pulses whose duration is determined by delay lines 32 in their grid circuits and triggered by the output of cathode follower valves 33 fed with positive pulses from the associated multivibrator. The outputs from the signal pulse generators are combined for transmission by the series connection of the output windings of transformers 31. One of the pulse generators is arranged to produce pulses different from the others in shape, amplitude or duration or may be a coded multiple pulse, for synchronizing purposes.