Patent GB-579672-A (GB)
Title: Improvements relating to pulse generating systems
IPC: H03K3/55
Filed: 1943-11-16
Abstract: 579,672. Impulse generators. STANDARD TELEPHONES & CABLES, Ltd., CHATTERJEA, P. K., and SCULLY, C. T. Nov. 16, 1943, No. 19140. [Class 40 (v)] [Also in Group XXXV] An improved arrangement for generating pulses of short duration and of sine-wave form by the charge and discharge of a condenser of capacity C includes a discharge circuit equivalent to an inductance of value L in series with a resistance of value R and'-such that R is not greater than #L/C. The opening and closing of the discharge circuit may be effected by gas discharge tubes or by other means such as a rotary spark-gap. Fig. 4 shows an arrangement for producing timephased pulses of a frequency determined by an alternating source 9. Condensers 5, 6 are charged through chokes 10, 11 which substantially tune the circuit to resonance and discharged through inductances'12, 13 into a load 16 through gas discharge tubes 14, 15. The load may be a cable, an aerial, a tank circuit or a further valve. The discharge tubes 14, 15 are controlled from pulse generator 9 through phase shifter 19 in a circuit which includes a bias source 18 and an auxiliary generator 17 from which the auxiliary time-phased pulses are obtained. As shown, signal waves from source 20 are fed to saturated inductance coils as described in Specification 551,282. Alternatively, the auxiliary rectangular duration modulated pulses may be produced as described in Specification 579,118, [Group XXXVIII], and fed to a differentiating circuit. Marking pulses alternating with fixed pulses may be used so that only alternate pulses are moved in time to represent the signal. Fig. 11 shows such an arrangement in which the fixed pulses are developed from pulse frequency source 21 through a frequency doubler 37, the output of which charges condenser 39 through a rectifier 25. The condenser 39 is discharged into the load 33 through an inductance 40 by a gas discharge tube 38. The gas discharge tube 38 is controlled by a saturated inductance auxiliary pulse train generator 41 fed with energy phase shifted in unit 42 and by a bias source 43. The time-phased pulses are generated by the charge and discharge of condensers 26, 27 through gas discharge tubes 30, 31 which are controlled by the auxiliary generator 34 producing rectangular timephased pulses. In a modification (Fig. 18, not shown), the fixed time-pulses are generated by a double condenser circuit to avoid necessity for frequency doubling. To avoid the need for use of considerable power at pulse frequency, a double moving pulse train in which consecutive pulses are displaced in time in opposite directions may be used. Fig. 19 shows such a system using a D.C. source 78 for charging condensers 75, 76 through a voltage doubling choke 79 and holdoff circuits 80, 81 which may comprise amplifiers biassed beyond cut-off. The hold-off circuits are controlled by a rectangular wave generator 82, controlled from the pulse generator 70 through phase shifter 85. The valves 71, 72 are fired by an auxiliary time-phased pulse train produced by the unit 83 from the pulse source 70 and signal source 84. Alternatively, a triangular or a saw-tooth wave may be used instead of a sine-wave as from the pulse source 70. To allow a longer de-ionising time for the tubes 71, 72, the phase shifter 85 may be controlled in accordance with the signal. Fig. 27 shows a multi-channel pulse system in which a harmonic generator 9 fed from a master oscillator 101 which may generate 10 kilo-cycles feeds amplifier 96 to charge the condensers 5, 6 through rectifiers 7, 8. The condensers are discharged through the tubes 14, 15 under the combined control of the signal channels CH1 ... CH10 and of amplifiers 99, 100 fed from a frequency doubler and saw-tooth generator 97 and of bias sources 102, 103. Each signal channel is fed with the frequency of 10 kilo cycles phased differently from the other channels by the phase shifters PS1 ... PS10 and converted into rectangular waves, as by a multi-vibrator, and having a duration of 10 per cent of the master oscillator period, which waves are time-phased in the channels CH1 ... CH10 as previously described.