GB332771A - Improvements in or relating to the reception and distribution of electrical signals - Google Patents

Abstract

332,771. Warwick, A., Taylor, J. A. A., and Holmes, H. C. Aug. 10, 1929. Selective signalling systems. -A system for distributing electrical signals, such as wireless programmes, over lines from a main station to a number of receivers comprises main-station indicating-apparatus which consists of a signal device operated by action at any one of the receivers and identifying means adapted to become operative by action at the main station. The signals may be distributed at high- or low-frequency. Faults at receivers may thus be reported to the main station. In the system shown in Fig. 1, programmes are distributed to stations A1 - - A3 over a line f connected to a wireless receiver or other lowfrequency source a represented by transformer b and situated at the distributing centre at which is located indicating and identifying apparatus B. When a. subscriber at one of the stations inserts plug p into sockets p2, a metallic circuit is completed over transformers s, b, switch j normally in engagement with j<1>, relay i and battery e. The circuit of bell m is closed and the operator throws switch j to connect up an ampere meter k, galvanometer or the like. The signalling circuits of the various stations are of different resistances so that the meter gives an indication of the calling station. As shown. resistances r1, r2, are inserted in the circuits at stations A2, A3. The system shown in Fig. 2 comprises groups of distributing lines fl - - f4 and F1 - - F4 connected by lines v, y, V, Y, to output transformers at the distribution station, condensers c1 - c4, C1 - C4 being interposed in one of each pair of distributing lines. The apparatus B is connected directly to line v, V, and by switches t, T to lines x, X, which are connected by switches u1 - -u4, U1 - - U4 to a conductor of each of the distributing lines which have a number of stations such as A1 - - A3, Fig. 1. The switches t, T, u1 - - u4, U1 - - U4 are normally closed and when the bell at B is rung, the operator manipulates switches t, T to discover which of the groups contains the calling station and then manipulates the switches u1 - - u4, U1 - - U4 to discover the calling distributing line, after which, by throwing in the meter at B, she can ascertain which station is calling.