GB499905A - Improvements in or relating to telegraph systems - Google Patents

Abstract

499,905. Multiplex telegraphy. WESTERN UNION TELEGRAPH CO. Oct. 12, 1937, No. 27698. Convention date, Oct. 21,1936. [Class 40 (iii)] In an expanding-channel system of the kind described in Specification 437,646, an expanding channel is operated in series with another expanding channel or with an ordinary traffic lane, through the medium of repeaters (such as reperforating receivers and retransmitters, or mechanical-storage retransmitters) which may be located at a central exchange, Fig. 1 (not shown). An expanding channel comprises a traffic lane, such as a channel of a multiplex distributer system, which is used by a group of transmitters sending characters in turn and is so arranged that when one transmitter ceases to send, the remaining transmitters of the group continue to send in turn without waiting for the excluded transmitter, so as to make full use of the line time available. For instance, a set of three transmitters located at New York, Fig. 2 (not shown), duplexed with set of receivers, feeds the line L 1 in the manner described with reference to Fig. 2 of Specification 437,646, except that in the present instance the lane comprises two channels, instead of one channel, of the multiplex distributer system for which the line L1 is used. At Albany, Fig. 3, segments 6 ... 10 of the receiving distributer feed a reperforating receiver 126 which feeds a retransmitter 127 sending to Chicago over an expanding-channel system. Segments 1 ... 5 and 11 ... 15 are used for the expanding-channel from line L1, which comprises sub-channels A, B, C. Of these, A feeds a reperforating receiver for retransmission to Boston through retransmitter 121, feeding into an expanding-channel system ; sub-channel B feeds a local printer at Albany; and subchannel C feeds a repeater for the Chicago expanding channel. The circuits for the receiving end of the expanding channel are similar to those described with reference to Fig. 2 of Specification 437,646, except that the expanding channel uses two instead of one of the channels of the receiving distributer RD.