Patent GB-455827-A (GB)
Title: Improvements in or relating to multiplex telegraphy
IPC: H04L5/22
Filed: 1935-12-02
Abstract: 455,827. Multiplex telegraphy. WESTERN UNION TELEGRAPH CO., 60, Hudson Street, New York, U.S.A. Dec. 2, 1935, No. 33327. Convention date, Dec. 17, 1934. [Class 40 (iii)] One channel of a multiplex system is assigned to one or other of two or more receiving instruments in response to switching signals sent at the end of a message. Reception and retransmission of messages, Fig. 1. Signals received from the line relay LR, Fig. 1, through one channel of the main distributer MD are applied to one or other of two receptacles RS1 and RS2 into which receiving or retransmitting sets have been plugged, according 'to the state of a switching-relay SS8; they are also applied through the receptacle MPR to a local monitoring printer. The first five impulses are applied to selecting-relays SR1 .. SR5 and those which are energized lock up until their locking- circuits are subsequently broken at contacts 4, 5 of sixth-pulse relay SP9. When brush b2 reaches segment 1 of local distributer ring LD the battery-supply relay BS6 is energized and the battery is applied at the right-hand contacts of this relay to circuits extending through the selected contacts 3 of selecting-relays S1 .. S5 and through cable D to the monitor-printer receptacle MPR ; and also to circuits extending through the selected contacts 2 of selecting- relays and cable A to the right-hand tongues of switching-relay SS8, and thence through cable C or cable E, according to the state of the latter relay, to receptacle RS1 or RS2 for reception or retransmission. When brush b2 reaches segment 2 of local distributer LD the sixth-pulse relay SP9 applies this sixth or operating pulse through its armatures 1, 2, 3, to the receptacles MPR, RS1, RS2, while its fourth and fifth armatures break the locking circuits of selecting-relays SRI .. SR5. Polarity of marking and spacing impulses. The system can be applied to a mixed-polarity system, in which the polarities that denote marking and spacing in the first two impulses are opposite to those in the last three impulses. The polarities applied to the locking circuits of relays SR1 ... SR5 can be changed by means of switches S4, S5; and either polar or non- polar apparatus may be plugged into the receptacles MPR, RS1, RS2. The armatures of the fifth relay SR5 rests on their marking contacts and respond to spacing signals only, in order to obviate a fault that would otherwise arise in connection with the switching over from station to station. The Specification gives details of polarity arrangements alternative to those shown in the drawing. Diverting signals to one or other of two receivers. When relay SS8 is de-energized, as shown, the signals go to receptacle RS2 through the right-hand five contacts of the relay. To divert the signals to receptacle RS1 it is necessary to send the figures-shift signal followed by letter F. The figures-shift signal sets the coded contacts 4 of relays SR1 .. SR5 so as to make a circuit for auxiliary switching relay AS7 through contact 2 of battery-supply relay BS6 when this pulls up. Relay AS7 thereupon locks itself. Letter F is next sent, and sets the coded contacts 5 of selecting-relays SR1 . . SR5 so as to make a circuit through contact 2 of relay AS7 to energize the stationswitching relay SS8, which diverts the signals to receptacle RS1 and locks itself. The letters-shift signal is then sent and sets the coded contacts (4) of relays SR1 .. SR5 so as to unlock relay AS7, while relay SS8 remains locked. When messages are subsequently to be diverted again to receptacle RS2, the figures-shift signal followed by letter S is sent, and coded contacts (5) are thereby set so as to unlock relay SS8 instead of energizing it. Retransmission of switching signals. The signals F and S may be either retransmitted or suppressed, as desired. In the former case they will go to the newly selected station, since the sixth or operating pulse applied by relay SP9 occurs after switching-over has been effected. To indicate the channel in the printed record, a special symbol may be cast on the slug for F or S. If, however, the switching signals are to be suppressed, in the case where polar instruments are to be plugged into RS1 and RS2, relay 10 is provided and is operated through coded contacts 6 of relays SR1 .. SR5 and through contact 3 of relay AS7. As a result, such polarity is supplied through the contacts of relay BS6 as will prevent the signals F and S from being sent on. Modification, Fig. 2. In a simplified arrangement the messages are normally received by instrument RS1, Fig. 1, as a result of the reception of the bell signal, comprising figuresshift followed by J, at the end of each message, while a message for instrument SR2 is prefixed by figures-shift and S. The coils of the selecting-relays SR1 .. SR5 are in series with the tongues of switching relay SS8 which do not, therefore, have to relay the signals. Their contacts are so coded, however, that the figuresshift relay FSR is energized through contacts 1 by the figures-shift signal and locks up, but is subsequently unlocked by the letters-shift signal through the same contacts. The figuresshift signal is followed by letter S, whereupon the switching-relay SS8 is operated through coded contacts 2 as soon as the sixth-pulse relay SP9 pulls up ; relay SS8 thereupon locks up and diverts subsequent signals to instrument RS2. Relay SS8 is unlocked by the bell signal at the end of every message by means of a circuit through coded contacts 3. The resetting relay RR is slow-acting and pulls up after the sixth-pulse relay SP9 has taken effect ; it acts to unlock the relay SP9 and to reset the relays SR1 .. SR5 by means of their lower coils. The bell and S signals are sent on, but the printer is modified mechanically to take account of this fact.