GB362914A - Improvements in or relating to receivers for frequencymodulated wave transmissions - Google Patents

Abstract

362,914. Wireless receiving systems. ROBINSON, J. and BRITISH RADIOSTAT CORPORATION, Ltd., 29, George Street, Hanover Square, London. Sept. 9, 1930, No. 26970. [Class 40 (v).] Frequency variations are isolated from a carrierwave having both amplitude and frequency variations by means of a beam or ray emitting device. The applied energy is arranged to cause the beam to reciprocate or move in a closed path and energize electrodes which are rendered active to a uniform extent. An electric resonator tuned to the upper or lower limit of the frequency variations is coupled to the electrodes to analyse the frequency variations. The Figure shows a receiving circuit 10 coupled to a cathode ray tube through a piezoelectric crystal 23 with which is associated condenser 24 to suppress interference as described in Specification 337,049, [Class 40 (v), Wireless signalling &c.]. The input is applied to deflecting plates 12 which control a strip-like beam impinging on electrodes 19 which energize a tuned circuit 20 with which a further piezo-electric crystal 25 is associated. Distortion due to low damping may be corrected as described in Specification 344,869. In a modification, Fig. 3 (not shown), the beam is caused to rotate by the provision of a second pair of deflecting plates arranged at right-angles to the first pair and fed with energy displaced 90‹ in phase. In this arrangement sector-shaped output electrodes are used and a number of pairs of these may be used to obtain frequency multiplication. A beam of light reciprocated by a mirror oscillograph between a pair of photo-electric devices, Fig. 5 (not shown), may alternatively be used.