Patent GB-1136071-A (GB)
Title: Improvements in or relating to communication systems
Inventor: CARTER ROBERT OWEN
IPC: H04B7/01
Filed: 1964-09-18
Abstract: 1,136,071. Radio signalling. H. M. POSTMASTER GENERAL. 17 Dec., 1965 [18 Sept., 1964], No. 38219/64. Heading H4L. A communication system includes digital storage apparatus at a ground station providing compensation for variations in the propogation time of a signal, e.g. in communication systems using artificial satellites, comprising a static digital store with means for introducing a variable time delay between the write-in and read-out of digits by varying the rate of readout so that the total of the propogation time of the link and the time delay introduced by the storage apparatus is substantially constant. A store of this type may be incorporated in the receiver of a ground station or in both receiver and transmitter. As shown in Fig. 1, satellite tracking by receiving aerial 1 is controlled by a computer 2 which also provides signals determining the additional delay to be added to the propogation time of the signals. Received signals are fed to a receiver 4 and converted to a baseband signal which is fed to a p.c.m. coder 5 whose output is stored at 6 under the control of "write" pulses from a clock 7. Initially the computer resets a "read" address counter 10 and a write address counter 8 via a reset pulse generator 16 and blocks pulses from "write" clock 7 and "read" clock 9 by means of INHIBIT gates 14, 15 respectively. The computer 2 then sets the "read" counter 10 on the required time delay and restores the outputs of clocks 7 and 9, at the same time controlling the frequency of clock 9 to ensure the required rate of change of the additional time delay. The store 6 may be of the cathode-raytube type, preferably with separate reading and monitoring beams. In a modification, Fig. 2 (not shown), a plurality of separate stores are used, each with its own write and read circuits and address counter and controlled by selectors so that reading and writing does not occur simultaneously in the same store. 1,136,077. Transistor pulse circuits. MARCONI CO. Ltd. 14 Jan., 1966 [9 Feb., 1965], No. 5641/65. Heading H3T. A pulse generator comprises a circuit which includes unilaterally conducting and substantially constant voltage dropping means (diode D1 and Zener diode D2), the circuit being rendered conductive on peaks of alternate half cycles of a high frequency oscillation (applied through transformer P, S), the resulting current through the circuit being employed to produce a voltage (across R1) which is applied to a transistor T to render it conductive, output pulses being taken from an output circuit of the transistor. Resistor R2 limits the base current if the high frequency source impedance is low. Improved rise and fall times are produced by the connection of a capacitor C across R2. The output may be taken from transistor T in emitter follower configuration. The transformer may be replaced by a pushpull transformer, each half of its secondary feeding an arrangement as shown for producing two trains of pulses separated by a half cycle of the input. The output pulse widths may be altered by adjusting the input amplitude or resistor R1.