GB157387A - Improvements in or relating to telegraphic or telephonic communication by single line without earth return - Google Patents

Abstract

157,387. Duverger, L. Jan. 21, 1919, [Convention date]. Addition to 157,385. Telephone systems; thermionic relays.-Relates to systems of the kind described in the parent Specification, utilizing a single line wire without return, and consists (1) in employing an auto-transformer, or a transformer having its two windings connected together, at the transmitting station, or (2) in transmitting the signals as modulations of high frequency currents. A microphone a, Fig. 1, acts through a transformer c, d on the line wire l, which may be a submarine or subterranean cable, and the line currents operate the receiver r after amplification by an " absorber " g of the kind described in the parent Specification A transformer may be inserted in the line, with one end of each winding connected to earth, or a condenser, one side of which may be connected to the armouring of the cable, so that the cable itself acts as a condenser. Two amplifiers g<1> g<2>, Fig. 6, may be connected in cascade between the line l and receiver r. In the arrangement shown in Fig. 7, a tube g, having its plates and grid circuits coupled by a circuit c, i<2>, d, generates oscillations which are modulated by a microphone a in the grid circuit and transmitted to line. Specification 157,386 is referred to.