GB299767A - - Google Patents

Abstract

299,767. Siemens & Halske Akt.- Ges. Oct. 31, 1927, [Convention date]. Two-way repeaters.-Multiplex signalling sys- -tems, of the kind in which several different channels of communication are provided by different frequency ranges, are arranged with echo eliminators individual to each channel, so that communication in one direction in one of the channels does not result in blocking the other channels for the opposite direction of communication. The line t, is branched into a west-toeast line with amplifiers a, b and an east-to-west line with amplifiers m, l, the whole forming a four-wire line ; and the line t2 is similarly branched. The west-to-east line is, before entering the echo-suppressing device, divided into different frequency channels by filters s1, s2, the channels uniting again after passing the ampli fiers c1, d1 and c2, d2 ; and the east-to-west line is similarly divided. When the amplifiers c1, d1 are active, the amplifier i1, is blocked by an echosuppressing connection p, of the usual type; but the other return channel of communication through the amplifiers i2, k2 remains open. Similarly if signals are passing from west to east along the channel a, b, c2, d2, the connection p, blocks the corresponding east-to-west channel at i2 but does not affect the other channel through i1, k1. The signals in the channels may be telephonic, telegraphic, picture-sending, television, or synchronizing impulses, and one or more may be modulated on a carrier wave; provided that they can be separated by the filters s1, s2 according to frequency.