Patent GB-182135-A (GB)
Title: Improvements in or relating to wireless signalling systems
IPC: H03D11/02
Filed: 1922-06-26
Abstract: 182,135. Armstrong, E. H. June 27, 1921, [Convention date]. Thermionic relays and repeaters.-A regenerative circuit is adjusted to the point at which, if impulsed, it would set up continuous oscillations, and, in that condition, a periodic variation is imposed either upon the retroactive coupling- factor, or upon the damping factor of the circuit itself, or upon both of these factors simultaneously. The circuit is then found to amplify with maximum efficiency without setting up selfoscillation, and, moreover, is rendered stable. This optimum condition is termed the state of super-regeneration. The frequency at which the above-mentioned periodic variations are imposed may vary from above audibility in the case of the reception of spark, modulated continuouswave, or telephony signals to a frequency below audibility where the received signals are intended to operate a recording-instrument. For receiving undamped signals, the imposed frequency may be that of the telephone note. Where a maximum degree of selectivity is desired, as in telegraphy, the periodic variation should be applied to the back-coupling factor only; whereas in telephony or in reception generally not requiring high selectivity, the periodic variation may with equal efficacy be applied to the damping-factor. In general, maximum efficiency is obtained by varying both factors simultaneously. With a high frequency of variation, the tuning becomes broad; in this way the regenerative circuit may be utilized with a small energy-loss factor as a substitute for known types of band-filters. The super-regenerative circuit may also be applied to wired-wireless reception. The Specification describes many different circuit arrangements for applying such a periodic variation to the backcoupling and damping factors. Fig. 3 shows a typical example of a retroactively-coupled valve circuit in which the back-coupling factor is varied by means of a second oscillating valve 29. The amplitude of the oscillations generated by the valve 29 is adjusted by means of the coupling between the coils 26, 27, and their frequency by the tuned circuits 25, 26 and 27, 28. The effect of these oscillations in the plate circuit of the amplifying-valve 23 is to vary the steady plate potential from the anode battery, and hence the degree of back-coupling between the grid and plate circuits of that valve. The signals are detected in tl circuit 24. Fig. 6 is a typical circuit in which the damping factor of the grid circuit is periodically varied, also by means of an auxiliary oscillating valve 63. The grid-filament circuit 64, 65 of the oscillating valve 60 is connected across part of the grid inductance 57 and resistance 58 of the amplifying-valve 60 by the tapping shown. In this way, the damping of the grid circuit 57, 58, 59 is varied in sympathy with the oscillations generated bv the valve 63. The amplifying-tube 60 in this arrangement acts also as a detector, and the telephones 62 are inserted in its plate circuit. The telephones may also be inserted in the plate circuit of the oscillating valve 63; tlis arrangement gives a double magnification. By making the frequency of the locallygenerated oscillations synchronous with the signal frequency, the zero-beat method of detection can be employed with advantage. In the circuit shown in Fig. 12, a single tube 131 performs simultaneously the functions of amplification, coincident variation of back-coupling and damping factors, and detection. The Specification gives the capacity and inductance values of certain of the circuits in detail, and also sets out the precise adjustments to be made in order to secure maximum efficiency in working.