Patent GB-680319-A (GB)
Title: Electrical pulse circulating apparatus
IPC: G11C21/00
Filed: 1950-09-29
Abstract: 680,319. Valve circuits; pulse storing circuits. WESTERN ELECTRIC CO., Inc. Sept. 29, 1950 [Sept. 30, 1949], No. 23884/50. Class 40 (vi). A pulse circulator comprises an amplifier, the output pulses from which are applied back to the input via a delay device and in which distortion of the pulse shape during circulation is corrected for and the amplitude of the circulated. pulses maintained constant. Fig. 2 shows a pulse circulator in which valve 22 which operates under Class B or C conditions comprises an expander-amplifier stage, the network 30, 32 providing an A.G.C. circuit, the time constant of which approximates to the required pulse period. The output from valve 22 is applied to an additional amplifying stage 42 via a frequency restrictive network 38, 40 which simulates the shunt impedances of the coupling circuit, and the output from valve 42 is applied back to the grid of valve 22 via a delay line 48. The delay of line 48 is made equal to the required interpulse interval and the circuit may be used to store an input pulse which has been introduced into the circuit or to operate as a pulse generator the circulated pulse then being derived from a noise pulse in the circuit. The pulse repetition frequency may be maintained constant by synchronizing pulses applied at terminals 51 and an output may be taken at 50, the widening of pulses due to the H.F. losses in network 30, 32 is compensated for by the sharpening action of the expander stage 22. In a modification Fig. 3 (not shown), the additional amplifying stage is dispensed with, the correct phase relationship being maintained by a transformer coupling between the output of the delay line and the expander-amplifier grid circuit. Fig. 4 shows a modification in which a reflex circuit is used, the output from the expander-amplifier valve 52 is applied via a delay line 56 to a short-circuited delay line 58, the reflected and inverted pulse from which is applied back to the grid circuit of valve 52. Fig. 5 shows a circuit suitable for the generation or circulation of pulses consisting of bursts of R.F. energy having a very high carrier frequency. The expander which is of the type described in Specification 671,989, [Group XL (b)], comprises a wave-guide hybrid junction 82, two conjugate arms of which comprise input and output circuits and the remaining conjugate arms include crystal rectifiers 84, 86, these latter arms being one-quarter wave different in length. The pulses from the expander are applied to the input of a travelling- wave tube amplifier 72 via a band-pass filter comprising irises 88, 90. The output of the amplifier is applied through a wave-guide hybrid junction 91 via a transmission line 92 back to the input of the expander 82. The expander 82 and B.P. filter 88, 90 sharpen and broaden the circulating pulses respectively, thus stabilizing the pulse length by their combined action. Automatic gain control is effected by an R.C. network 94, 96 in the D.C. path of rectifiers 84, 86, which limits the rate at which the rectifier impedance may change. Output pulses may be taken from wave-guide branch 98 and the pulse repetition frequency may be synchronized by pulses applied at terminals 95, or the carrier frequency synchronized by a pulsed R.F. oscillator 91<SP>1</SP> fed into the wave-guide junction in place of termination 99. Fig. 7 shows a reflex R.F. pulse circulator in which an expansion characteristic is obtained by reflecting the pulses from a crystal rectifier 100 which is mounted on and matched to wave-guide 102 at low amplitude levels. Automatic gain control is obtained by the use of R.C. network 104. Pulses reflected from crystal 100 are applied to the input of travelling-wave tube amplifier 108 via B.P. filter 106, the output of the amplifier is divided, half to output 112 and half to the input of a short-circuited delay line 114. The energy reflected from the end 116 is divided again at the junction and half traverses the helix of amplifier 108 and appears back at the expander 102. Synchronism may be effected as described in connection with the circulator shown in Fig. 5.