Patent GB-905923-A (GB)
Title: Improvements in and relating to a system for the generation and transmission of pulse groups
IPC: H04M1/278
Filed: 1960-02-09
Abstract: 905,923. Impulse transmitters. KANDA TSUSHIN KOGYO KABUSHIKI KAISHA. Feb. 9, 1960 [Feb. 14, 1959; Feb. 23, 1959], No. 4603/60. Class 40 (4). In an impulse transmitter for use either by a subscriber or by a register sender, a commercial A.C. on lead 10, Fig. 1, is frequency divided at A to produce shot pulses at 10 i.p.s. which are applied to a gate B which is opened for a duration corresponding to the digit to be sent, the short pulses being then applied to trigger an impulse generator C which generates impulses of the correct duration for onward transmission by a relay P. The gate B is controlled by a flipflop E whose relaxation time is controlled by a circuit F which contains means for varying, in accordance with the digit to be transmitted, either a capacity or a resistance in a time-constant circuit of the flip-flop. A triggering pulse for the flip-flop E is derived from the output of A via a gate D opened by a control circuit G which contains means to ensure an adequate inter-train pause. As shown, Fig. 12 (F, Fig. 1), push-buttons (not shown) may be operated to connect up resistances RT3 . . . appropriate to successive digits to be transmitted. Operation of a start button SB restores (by means not shown) the circuits of Fig. 13 (G, Fig. 1), Fig. 10 (E, Fig. 1- and Fig. 2 (A, Fig. 1). In Fig. 2 incoming 50 or 60 c.p.s. on lead 10 is squared and differentiated to trigger the flip-flop V 2 , V 3  which remains in this state for 10 msec. after which it restores and is then retriggered. The flip-flop output is amplified by V 4  and differentiated to provide short pulses to gates D and B, Fig. 1. The operation of button SB also operates relay M which looks and connects resistance RT 3  in the position RT of circuit E, Fig. 10. Meanwhile with V 14  non- conductive in Fig. 13 the output G 3  opens gate D to pass short pulses from A to E the first of which triggers V 10  on, and the circuit stays in this state until it restores due to condenser CT discharging. During this interval the positive output on lead 14 opens gate B to pass pulses from circuit A to the circuit C which consists of a flip-flop operating a relay P to give the required 2-1 break-make ratio. Meanwhile relay K has been operated due to V 13  being enabled from lead 14. At the end of the period V 10  cuts off and V 11  comes on. Valve V12 is thereby caused to conduct and anode relay J operates momentarily during the release time of K. Relay J triggers the flip-flop V 14 , V 15  to disable gate D. After a period equal to the intertrain pause V 14 , V 15  restores. Meanwhile operation of J operates U and releases M so that the resistor RT 4  appropriate to the next digit is connected up. Thus after the intertrain pause the next digit is sent and so on. In a modification the condensers, instead of the resistors, are variable. Each digit of a subscriber's number is recorded in a column in binary code by holes punched in a card. When the card is inserted in a sensing device, capacitance to the value represented by the holes is connected to contacts of a stepping chain for successive insertion in the circuit E, Fig. 10, in the position marked CT. Push buttons instead of punched cards may be used. Transistors may replace valves.