GB479731A - Improvements in or relating to signal transmission systems - Google Patents

Abstract

479,731. Copying - telegraphy. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. June 7, 1937, No. 15766. Convention date, June 5, 1936. [Classes 40 (iii) and 40 (v)] To improve the definition of the reproduction, a transmitter is controlled by at least a current or potential which varies with the rate of change of intensity of potentials or currents which vary with variations in the subject 10. The latter potentials or currents may also be transmitted. The former potentials are applied to a controlling grid 31, and the latter to a controlling grid 30 in a thermionic valve 32. The original potential is produced by light scanning contrasting markings in the subject and falling on a photo-electric cell 24, the current from which is applied to an adjustable resistance-reactance circuit R, C to produce the derived potential. The combined signals modulate a carrier at 40. Both sets of potentials may be applied to a single controlling grid, Fig. 3 (not shown). According to modifications : a capacity is shunted across the resistance 33, Fig. 1b (not shown) ; the circuit RC is replaced by a transformer, Fig. 2 (not shown) ; the potentials are applied directly to the modulator, Fig. 4 (not shown).