GB159683A - Improvements in or relating to wireless reception apparatus - Google Patents

Abstract

159,683. Robinson, J., and Crowther, H. L. Dec. 17, 1919. Receiving systems and apparatus; thermionic detectors; heterodyne receiving systems.-In a wireless reception apparatus of the kind described in Specification 153,690, the intensity of the received waves is caused to vary a resistance connected to an oscillatory circuit. Preferably two local oscillators are provided, beating with each other, and the varying resistance is connected to one of the local oscillators to vary its frequency and thus alter the pitch of the beat note. As shown in Fig. 1, the output circuit of the last low-frequency amplifier 5 is connected by e. transformer 6 through a condenser and grid leak 8 to the grid and filament of a valve 7. The plate-filament resistance of this valve is thus varied according to the intensity of the received signals. Two valve oscillators 10, 12 producing oscillations of slightly differing frequency give a beat note in the telephone 16. The varying resistance 7 is shunted across the tuned plate circuit of one of the oscillators 10, thus varying the frequency of this oscillator and varying the pitch of the beat note. Fig. 4 shows a modification in which highfrequency energy is applied direct to the grid of the variable-resistance valve 19. This valve may be connected to the local oscillators in the manner shown in Fig. 1. As shown in Fig. 4, it is connected in series with the plate battery'20 of the oscillator 21. The incoming energy thus varies the effective potential applied to the plate of the oscillator 21, and alters the frequency of this oscillator and the pitch of the beat note.