Patent GB-721913-A (GB)
Title: Improvements in or relating to telegraph repeaters
Inventor: RIDLER DESMOND SYDNEY
IPC: H04L5/16
Filed: 1952-06-27
Abstract: 721,913. Telegraph regeneration repeaters. STANDARD TELEPHONES & CABLES, Ltd. June 19, 1953 [June 27, 1952], No. 16249/52. Class 40 (3). In a telegraphic communication system in which signalling may take place alternately in either direction between two stations, an electronic regenerator repeater is provided together with means for automatically connecting the repeater to regenerate signals from whichever of the two stations is transmitting. The invention is described in relation to a telegraphic exchange system in which the connection and dialling between a station and the exchange is effected over a line independently of the regenerator repeater which is only switched into the line when the connection to the wanted station is established. Fig. 1 (Provisional) shows one station 1, 3, 9 and an electron regenerator repeater 2, the transmitted signals appearing on T1 and being connected through the exchange to the receiver of a second station whilst incoming signals are received at T2. To call the exchange a key on control box 1 is operated to send a long mark signal via contacts RE1 and RE2 by-passing the regenerator 2. The exchange sends back a " proceed-to-dial " signal consisting of mark lasting for less than 100 ms. This by-passes the regenerator at contacts RE4 and RE3, and controls the receiver 3 to start the teleprinter motor in known manner. The " proceed-todial " signal also passes to a gating device comprising two gates G1, G2 and a delay device D having a delay of 100 ms. To operate, gate G2 requires the simultaneous application of signals at its two inputs and fails to respond, therefore, to the " proceed-to-dial " signal. At the completion of dialling, line T2 is left in the mark condition. When the exchange has established contact with the wanted station, a mark signal is returned to T2, this signal persisting for at least 100 ms. and therefore passing through the gating device to change over a two-condition device F1 and operate relay RE. The regenerator is then brought into circuit at RE1- RE4 and power applied at RE5. The regenerator is of the type described in Specification 692,411 and operates under the control of send and receive modulators 5 and 6. When either station starts to transmit, the start space signal causes a pulse to pass from the corresponding modulator 5 or 6 to trigger a twocondition device F2. This then operates contacts CO2 and CO3 to connect the regenerator to receive and re-transmit in the appropriate directions. Thus, for example, when the home station is transmitting, the contacts are set as shown so as to connect modulator 5 to the input of the regenerator and the re-transmitting contacts TR1 to the outgoing line T1. Contacts CO1 are also changed over so as to apply a mark holding potential to the receiver of the transmitting station. At the completion of signalling, a long space signal is applied from the regenerator to reset two-condition device F1 and release relay RE. Fig. 2 (Provisional, not shown), shows circuit details of the gating device G1, G2, D. In a second embodiment, of which Fig. 2 (Complete) shows part of the circuit in detail, the change-over relay is dispensed with and the send and receive modulators are rendered effective alternately in dependance upon which station is transmitting by means of an electronic switch. In Fig. 2, the send modulator (not shown) produces positive pulses on a mark or space lead depending upon which condition is received by the modulator and controls a relay TRA through output device SOA, MOA. The contacts of relay TRA connect with the outgoing line. In a similar manner, the receive modulator controls a second relay TRB through output-device SOB, MOB, the contacts of TRB connecting with the teleprinter receiver. As described in Specification 692,411 the pulses on the respective mark and space leads are ineffective to trigger the output devices due to short-circuits provided by rectifiers X3-X4 and X15-X16 connected from the leads to conductors 9 and 10. A time scale circuit in the regenerator is started up at the start of a signal and thereafter at intervals of 10, 30, 50, 70, 90 and 110 ms., i.e. at the theoretical centres of the start element and five permutable elements, potentials are applied simultaneously to conductors 9 and 10 to block the rectifiers. The modulator pulses are then effective to trigger the output devices and control relays TRA and TRB accordingly. In order, however, that only the modulator connected to the transmitting station shall be effective at any time a further control of the mark and space leads is effected by means of a two-condition device TS, TR. From the mark and space leads of the send modulator connections extend through rectifiers X10 and X9 to the cathode of TS, and from the mark and space leads of the receive modulator. Similar connection extends through rectifiers X18 and X17 to the cathode of TR. Only when TS or TR is conducting are the rectifiers blocked to allow the mark and space pulses to become effective. On receipt of a start space pulse from the send modulator TS is triggered over C7 extinguishing TR. The send modulator is then rendered effective and the receive modulator blocked. In a similar manner receipt of a start space pulse from the receive modulator triggers TR over C8 and reverses the condition to render the receive modulator effective and block the send modulator. Specification 636,700, [Group XL (c)], also is referred to.