Patent GB-472529-A (GB)
Title: Arrangement of start-stop regenerative repeaters for two-way repetition of signals
IPC: H04L25/42
Filed: 1937-04-09
Abstract: 472,529. Code telegraphy. STANDARD TELEPHONES & CABLES, Ltd. April 9, 1937, No. 10158. Convention date, April 16, 1936. [Classes 40 (iii) and 40 (v)] A start-stop regenerative two-way repeater comprises means controlled by the arrival of signals in one direction for re-transmitting the signals in that direction and for preventing transmission in the opposite direction until the re-transmitter returns to normal. Separate or common regenerative devices may be used for the two directions. The regenerators may comprise retransmitting contacts set in accordance with the position of an armature of a receiving magnet and timed by a startstop cam-shaft as described in U.S.A. Specification 1,956,704, or start-stop distributers. In the arrangement shown in Fig. 1 using separate regenerators 101, 102, the receiving magnet M of each is connected to the contacts of the line relays 103, 105 respectively over off-normal contacts L of the other. When a start signal operates relay 103 to spacing position, normally operated magnet M of regenerator 101 is released to start the cam-shaft whereby off-normal contacts L lock magnet M of regenerator 102 and connect spacing battery to transmitter contacts T of 101. The cam TC then opens the operating circuit of 106 at retransmitting contacts T and a spacing impulse is sent to line over SE. The signal impulses are then transmitted and when the regenerator stops, the off-normal contacts restore and the entire repeater assumes the normal condition. If a break signal is received by relay 105 while regenerator 101 is operating, the regenerator is not affected, but when it reaches normal, regenerator 102 is started up. In a modification, Fig. 2 (not shown), a winding of each line relay and the re-transmitter contacts are in a normally closed loop circuit from the distant station and transmission in the opposite direction is blocked by a biassing winding fed by a potentiometer controlled by the off-normal contacts of the operating regenerator. Modification, Fig. 3, using gas-filled valves for one of the line relays. The battery potentials indicated by squares are derived from a separate ungrounded battery and the grid potentials of the valves are controlled by series resistances 321, 322 in normally closed loop LE. Normally, the potential drop between points 323, 324 balances negative grid battery 326 so that valve 331 is conducting and condenser 361 discharged, whereas the drop between 324, 325 biasses valve 332 negatively, condenser 362 being charged due to the non-conducting condition of the valve. On receipt of a spacing (break) signal over LE valve 331 is biassed by the negative battery only, whereas 332 is unbiassed and becomes conducting so that condenser 362 discharges and the effect of the voltage kick over transformer 352 reduces the anode voltage of 331 which ceases to conduct and releases magnet M of regenerator 302, the off-normal contacts of which hold magnet' M of regenerator 301. When loop LE is closed again, the valves are reversely controlled and magnet M is reoperated. The signals are repeated by contacts T to line LW over line relay 303 which is arranged in a differential circuit and does not operate. When the regenerator has stopped and transmission occurs in the opposite direction, the valves 331, 332 are operated in a similar manner by the transmitter contacts T of regenerator 301, but this has no effect on regenerator 302 since its magnet M is held by the off-normal contacts L of 301. Modification, Fig. 4, using the same regenerator 400 for both directions. Regenerator magnet M is controlled in a circuit including the contacts of both line relays 403, 405 in series so that it may be released by either, and the transmitter contacts T are connected to the operating windings of the sending relays 404, 406 in parallel. Normally, current in the operating windings of relays 403 ... 406 holds the relays in marking position against opposing weaker force in biassing windings, relays 404, 405 being biassed by negative battery over resistance 412 and 403, 406 by positive battery over resistance 411. On receipt of a start (spacing) signal over LW, 403 applies positive battery to the left winding of direction controlling relay 410 which holds on, or changes over its contact to E, magnet M being also released to start the regenerator. The positive battery from E is then connected over offnormal contacts L to reverse the bias on relays 404, 405 to hold them in marking position to prevent transmission in the opposite direction, and to maintain the normal bias on 403, 406, which therefore act as input and output relays of the regenerator. The circuit is symmetrical and when the regenerator is normal, transmission in the opposite direction takes place in a similar manner, relay 410 being operated to contact W to disable relays 403, 406. In a modification of this arrangement, Fig. 5 (not shown), the sending relays (404, 406) are dispensed with by connecting the transmitting contacts T directly in one or other of the lines by a switching relay controlled by the direction-controlling relay.