GB372852A - Improvements in or relating to telegraph systems - Google Patents

Abstract

372,852. Multiplex signalling. COVENTRY AUTOMATIC TELEPHONES, Ltd. and LEY, D. A., of General Electric Co., Stoke, Coventry. Feb. 25, 1931, No. 5879. [Class 40 (v).] In a multiplex system employing a thermionic distributer, the number of valves required is reduced by division of the distributer into two parts. One of these scans the transmitters or receivers, arranged in groups each comprising K instruments, at the rate of N groups per second, while the other scans the same instruments, in a different grouping, at KN groups per second. Each distributer comprises, a set of valves D1 .. D4 or E1 .. E4, controlled by a source B or C of grid bias. The source B, for instance, emits waves of multiple frequencies, and these are superposed in groups, as described in Specification 302,180, [Class 40 (v), Wireless signalling &c.], so that four composite waves, each having a short peak at the appropriate instant and being individual to one of the valves, are so applied as to open each of the valves D1 .. D4 in turn at a rate of N complete cycles of operation per second. Similarly, a set of four composite waves from the oscillator C opens the valves E1 .. E4 in succession at the rate of KN operative cycles per second where K = 4 = N. The transmitter contacts W .. Z are so grouped that only one complete channel is open at a time from source G to line L. A similar arrangement may be used at the receiving station. Alternatively the connections may be rearranged so that valves D operate at KN and valve E at N groups per second.