GB566934A - Improvements in telephone or like systems - Google Patents

Abstract

566,934. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. July 15, 1943, No. 11516. Convention date, Sept. 11, 1942. [Class 40 (iv)] In an inter-exchange system, each train of impulses is converted at an outgoing repeater into a single impulse of variable duration which is converted back to the original form at an incoming repeater. As shown, repeaters 100, 400 terminating a two-way junction 10 are accessible to first selectors 104, 404 and are individual to incoming selectors 105, 405. A simplex circuit on the junction which includes relays R255, R260, R265 in the repeater 100 and R355, R360, R365 in the repeater 400, is normally earthed at both ends, and upon seizure of the repeater 100, guard relay R130 replaces the earth connection at that end by battery, causing the operation of all the relays except R265, this relay and R365 being polarized to energize only on incoming calls. R130 also disconnects the incoming selector 105. Each impulse train is repeated by line relay R140 to a step-by-step switch 200, the arcuate wiper 201 of which bridges a number of terminals equal to the number of impulses. As soon as this switch moves off-normal, relay R290 connects up R180 to open the simplex circuit and starts a clutch-driven switch 210 which performs a single rotation and then unlocks R290. The terminals of the switches 200, 210 are interconnected to maintain R180 as long as wiper 211 encounters terminals that are marked over the arcuate wiper 201, whereupon the outgoing impulse is terminated. The switch 200 is restored on the relapse of dialling relay R120. At the repeater 400, the initial operation of polarized relay R365 energizes seizure relay R370, whereupon cut-off relay R470 closes a loop through R460 to the incoming selector 405. During the relapse of R365 in response to each digital impulse, a clutchdriven commutator 321 rotates to control R350 and a condenser 339 is alternately charged and discharged through impulse relay R345. R340 operates to shunt R460 to improve the impulsing circuit. The current reversal on the reply of the called party operates R460, which opens the upper leg of the simplex circuit, so that R355 and R255 fall back and the latter connects up reversing relay R150 to repeat the reply signal. When the calling party hangs up, the relapse of R140 causes the transmission of an impulse corresponding to the digit 1 which is without effect on the selector train at the distant exchange, and the subsequent relapse of guard relay R130 reconnects earth to the simplex circuit, whereupon the continued release of R365 causes the relapse of seizure relay R370, which is retarded by a dashpot. R470 in falling back opens the loop to the incoming selector 405 and shunts down the line relay of the connector. Specification 555,097 is referred to.