GB611727A - Pulse communication system - Google Patents

Abstract

611,727. Radio signalling. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Oct. :3, 1945, No. 25767. Convention date, Feb. 17, 1944. [Class 40 (v)] In a relay station for use in a pulse communication system the received pulses engender corresponding transmitted pulses occurring after a delay such that a pulse is transmitted only during the interval between the reception of its engendering pulse and the next received pulse. The receiver is blocked during this interval, and the transmitted pulses may be modulated in phase locally. In the embodiment described, the receiving aerial RA feeds R.F. amplifier 90, followered by frequency charger 91, I.F. amplifier 92, rectifier 94, clipper 95, coupling device 100, pulse frequency selective circuit 101, converting the pulse output to a sine-wave form, limiter 110, discriminator 111, low-pass filter 112, A.F. amplifier 113 and reproducer 114. A second output from coupling device 100 feeds a further coupling device 102 from which independent pulse outputs are fed to delay devices 103, 104. The output of the latter controls a blocking pulse generator 109 which disables I.F. amplifier 92 for a desired interval between received. pulses. The delayed pulses from circuit 103 control a pulse generator 105 feeding a power amplifier 106 which modulates the R.F. generator 107, connected to the transmitting aerial TA. Provision is made for locally modulating the delay produced by circuit 103 by the output of an amplifier 108 supplied with keying or modulating energy. The circuits of devices 100, 102, 103 and 109 are shown in Fig. 2. The negative pulses from clipper 95 are reversed in section a of double triode 100 and passed in parallel to both sections of valve 102, and also to section b of valve 100 in which they are reversed again for application to the selective circuit 101. The outputs of valve 102 feed the delay devices 103, 104, which are similar, the circuit of device 103 being shown. It comprises a flip-flop multivibrator 13, the steady grid bias of section b of which is adjustable by resistance 20 to control the output pulse duration. The negative output pulses are differentiated in circuit 15, 16, the positive pulse corresponding to the trailing edge rendering valve 17 conducting, to pass on a positive pulse from its cathode 18 to the pulse gerierator 105. Local modulation of the duration of the pulses from valve 13, and hence of the phase of the pulses in valve 17 is produced by the transformer 21 connected in series with resistance 20 and fed from a microphone M through amplifier 108. The output from delay device 104 controls a flip-flop multivibrator 120 to produce positive pulses of a duration adjusted by the variable cathode resistance 122, which are fed to the control grid of valve 121. The anode of this valve is connected to the screen grids of the valves in I.F. amplifier 92 which are thus given a lowered potential during the blocking period between received pulses. Specifications 574,627 and 594,659 are referred to.