Patent GB-346301-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone exchange systems
IPC: H04Q3/00
Filed: 1930-01-07
Abstract: 346,301. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., HARTLEY, G. C., and WRIGHT, E. P. G., Columbia House, Aldwych, London. Jan. 7, 1930, No. 610. [Class 40 (iv).] Repeaters have an alternative through metallic circuit which is connected up in the case of a call from an operator so that busy &c. signals may be passed back without repetition. A metallic circuit may also be normally connected up so that impulses and particularly code impulses may be transmitted forward without repetition. Figs. 1, 2, 3, show repeater circuits for use in the byepath system described in Specification 346,368 for calls to a. tandem office, to a coder-call-indicator manual office, and to a directly-reached automatic office respectively. Zone-metering arrangements are associated with each repeater, metering for tandem calls being variable according to a signal sent from a register translator whilst for other calls a fixed charge is made at each repeater. Tandem repeater, Fig. 1. Relay BS operates over the test conductor BPT from the byepath and energizes JS. Impulses coming over the byepath conductors BP-, BP+, pass directly through the repeater, and at the end of the transmission when the connection has been extended over the talking-circuit selector, relay AS operates, energizing relay HS. The connection of metering ground at the register-translator to one or other or both of the byepath leads BP-, BP+, controls relays MX, MZ. When the called subscriber replies, relay DS releases relay HS causing a start signal to be transmitted over lead S to common metering apparatus of the type shown in Specification 345,267 whereby the appropriate number of booster metering impulses is transmitted over leads B, H. At the end of the cycle, relays MX, MZ are short-circuited over lead SC. In the case of a call from an operator, the connection of direct earth to lead H releases relay JS, AS, BS. A through metallic circuit is thus extended through the repeater and since relays MX. MZ are not locked up metering is prevented. Repeater to coder-call-indicator exchange, Fig. 2. Relays BS, HS, JS operate on seizure and the code impulses from the byepath pass directly through. For an ordinary call, at the end of code-sending relay AS operates to complete the outgoing loop and when the called subscriber replies relay DS energizes and connects ground to the metering start lead whereby a fixed number of booster metering impulses as determined by the wiring F individual to the repeater is transmitted over leads B, H. Relay HS is then short-circuited and releases. For a call from an operator, relay JS releases and a metallic circuit is extended through the repeater. Direct-junction repeater, Fig. 3. On seizure,' relays JS, AS, BS operate, completing an outgoing loop. When the distant exchange is ready to receive impulses relay IS operates, energizing relay MS which short-circuits a resistance in the incoming loop to repeat this signal back to the byepath. Incoming impulses are repeated by relay AS, and at the end of the transmission, relay HS operates. When the called subscriber replies, relay DS energizes to initiate metering which takes place as in Fig. 2. For a call from an operator a direct earth on lead H releases relay JS to complete a throughmetallic-circuit as before. In the repeater of Fig. 3 a single pair of incoming leads is multipled to the positive and negative leads from the byepath and from the conversation selector.