GB222616A - Improvements in or relating to multiplex telegraph systems - Google Patents

Abstract

222,616. Automatic Telephone Manufacturing Co., Ltd., and Harrison, H. H. Aug. 10, 1923. Multiplex telegraphs; quadruplex teleyraphs; distributor systems.-In a multiplex system using an equal letter code, such as the Baudot. two sets of signals are sent simultaneously over each channel, the first set by currents of opposite polarity, and the second set by currents of modified strength, and the controlling arrangement is such that the reversal of polarity and the modification of strength can only be effected simultaneously. Fig. 2 shows an arrangement for operating over a channel between transmitters TR<1>, TR<2> at station A and the corresponding type-printing receivers PMG<1> and PMG<2> at station B. The closing of a contact of the transmitter TR<1> enables the distributor brush to complete a circuit through an electromagnet R<1> thereby attracting an armature r<1> to connect positive battery BR to line L in place of negative battery BR<1>. The closing of a contact of the transmitter TR<2> enables the distributor brush to complete a circuit through an electromagnet R<2> thereby attracting an armature r<2> to short-circuit a series resistance SD and to disconnect a leak resistance LR from the line, thus increasing the strength of the currents sent to line. At station B a non- polarized marginal relay NPR and a polarized relay PR are connected to the line in series and control the receivers PMG<2> and PMG<1> respectively. The system may be made quadruplex on each channel. In a modified arrangement one only of the relays NPR, PR controls a local receiver while the other serves to retransmit the signals over a second line. Specification 221,556 is referred to.