GB608778A - Pulse communication repeater system - Google Patents

Abstract

608,778. Radio signalling. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Jan. 10, 1946, No. 958. Convention date, April 7, 1944. [Class 40 (v)] A repeater station for a pulse-modulated radio communication system includes a continuously operative receiver, means for deriving D.C. pulses from the received pulses, a generator of short D.C. pulses synchronised by the derived pulses and arranged to be irresponsive to pulses received in the intervals between the signal pulses and a radio-frequency oscillator fed with the generated pulses to produce R.F. pulses corresponding in spacing to the received pulses. The R.F. pulses received on the aerial 10 are reduced to an intermediate frequency in mixer 12, and converted to D.C. pulses in a rectifier 15. The derived pulses are fed to a local monitor circuit, and through a switch S to a pulse generator comprising a valve 21, the anode and control grid of which are connected to separate windings of a pulse transformer 20. An artificial line L, one end of which is connected between the cathode, maintained at a positive potential, and earth, has a constant current valve 22 connected across it. The operation of the pulse generator is described in Specification 594,659. When the system is acting as a repeater, the grid bias and cathode resistances of modulator valve 22 are such that the natural period of the pulse generator is longer than the greatest interval between two consecutive received pulses, but the voltage across line L is dissipated sufficiently rapidly to enable the derived pulses applied through switch S to trigger the pulse generator. The pulse generator may be disconnected from the rectifier 15 by opening switch S, and repetition frequency modulated pulses produced by closing switch S1, thus increasing the current flowing through valve 22, the conductivity of which is varied by modulating signals applied to the control grid. The output of the pulse generator 21 is taken from transformer 20 to control a magnetron oscillator 24, which feeds an aerial 25.