GB624542A - Improvements in or relating to receivers for multichannel pulse communication systems - Google Patents

Abstract

624,542. Multi-pulse radio signalling ; pulse modulation. STANDARD TELEPHONES & CABLES, Ltd. June 6, 1947, No. 14993. Convention date, March 2, 1946. [Class 40 (v)] In a multi-channel receiver, Fig. 1, for timemodulated pulses, wherein synchronizing pulses are separated from the signal pulses in a marker separator 17, and the signal pulses and synchronizing pulses are fed to selector circuits 21 corresponding to the channels and converted into width-modulated pulses for the operation of integrating circuits 22 and utilization devices 23, each selector circuit 21 comprises a .multivibrator, Fig. 2, triggered by the synchronizing pulses and restored by the signal pulses in the corresponding channel. In the absence of a signal pulse the multivibrator is restored to its original condition after a time equal to the maximum time between a synchronizing pulse and a signal pulse of the selected channel, the time being determined by a resistor condenser combination 34, 31. Pulses of channels later than the desired one have no effect on the output of a valve 25, due to the valve being run at saturation point and pulses occurring before the desired channel pulses are prevented from restoring the multi-vibrator by an inductively tuned circuit 43, which on arrival of a synchronizing pulse sets up a blocking or negative undulation lasting for a time slightly less than the minimum time between synchronizing pulse and a desired signal pulse, and of such magnitude that pulses of other channels are insufficient to render conducting again valve 25, which is rendered non-conducting on the application of a synchronizing pulse to a normally cut-off valve 24. Any positive undulation is prevented by a diode 46 in parallel with the tuned circuit. The variable inductance 44, resistor 34 and condenser 31 are ganged together so as to effect simple channel selection.