GB398616A - Improvements in or relating to systems for the distribution of music, speech or the like over line wires - Google Patents

Abstract

398,616. Distributing music &c. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, CLARK, F. and CHUBB, A. A., c/o General Electric Co., Stoke, Coventry. June 17, 1932, No. 17139. [Class 40 (iv).] In a system for distributing music &c. programmes over line wires, a plurality of receiving sets J1 .. J4 at an unattended station, Fig. 2, remote from electrical disturbances, are selectively connected up and supervised by an operator at a central control and distributing station, Fig. 1. When the dial IP is operated, a simplex circuit is closed over dial-off-normal contacts ON, differential relays L, Y, and line wires L1, L2, for relays A, D, which operate followed by relays B, G. Impulses are repeated by relays A, D, to step-by-step switches V1 .. V3, R1 .. R3, the former indicating at V2 the set selected whilst the latter connects up over R1 the required set to the line wires and completes over R2 a starting circuit for the set selected. A monitoring loud-speaker MS indicates correct operation. The simplex circuit remains closed over contact b2 until release key RK is operated when both selectors return to normal. If the power supply at the receiving station fails, a normally-operated relay H releases, switching off the set in use and unbalancing the simplex circuit so that relay L energizes operating an indicator LF and an alarm relay AL which switches over to a stand-by set and gives bell and lamp alarms. Relay AL is locked over bank V3 and is only unlocked by dialling one particular number so that tests on the line and receiving sets may be carried on without any effect on the stand-by programme. Similar operation takes place if an earth or break occurs in either line wire and relay H also releases (by short-circuiting) if switch R1 .. R3 fails to release. The line wires and selecting apparatus may be duplicated to afford alternative programmes.