GB452473A - Improvements in and relating to diplex telephony and telegraphy - Google Patents

Abstract

452,473. Diplex telephony &c. RADIO INDUSTRIE, 24, Rue du Docteur-Finlay, Paris. Jan. 17, 1936, No. 1608. Convention date, Jan. 19, 1935. [Class 40 (iv)] In diplex telephony or telegraphy, distribution is effected by the superposition on the transmission line of alternating current of inaudible frequency and the use of suitably poled dry contact rectifiers. As shown in the Figure, simultaneous conversations can occur over jacks 8, 9 at one station and corresponding jacks 81, 91 at another station. The distributer source 1 is connected across line 2, 3 in series with tuned circuits which reject telephonic currents, and the jacks 8, 8<1>, 9, 91 are connected to the line over transformers 10, 10<1>, 11, 11<1> shunted by capacities to permit passage of distributer current, the branches in which jacks 8, 81 are connected having rectifiers 14, 14<1>, 19, 191 similarly poled in one direction, whereas the other branches leading to jacks 9, 9<1> have similarly poled rectifiers in the other direction. The various branches have adjusting resistances, e.g. 6, 15 for balancing the system about neutral points, e.g. 17, which may be grounded and connected to metal frames &c. Calling is effected by direct current which, in accordance with its polarity, operates corresponding calling devices 18, 181 at both stations. In a modification, Fig. 2 (not shown), alternating current sent over one or other of the line wires, is used for calling, the telephone sets and calling devices of the two circuits being oppositely connected to the line wires.