Patent GB-805396-A (GB)
Title: Improvements in or relating to telephone systems
Inventor: READ DOUGLAS AUSTIN
IPC: H04Q3/42
Filed: 1955-09-22
Abstract: 805,396. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO. Ltd., and BRITISH TELECOMMUNI- . CATIONS RESEARCH Ltd. Sept. 6, 1956 [Sept. 22, 1963], No. 27039/55. Class 40 (4). In an exchange employing register-senders of the code-translating type, the registersenders are arranged in two groups used for controlling the setting up of different types of connection, at least one of the groups being accessible from outlets of an auxiliary switch taken into use on the initiation of a call. In the embodiment described, one group of registersenders controls the setting up of connections within the local multi-exchange area and is accessible from the A-digit switches in response to certain values of the initial digit dialled, while the other group of register-senders controls the setting up of connections outside the local multi-exchange area and is accessible from the first code selectors in response to an initial digit having a different value. As shown, ordinary subscribers' lines OS and coin-box subscribers' lines CS have access through their respective uniselectors SU to 1st code selectors FCS,. When a subscriber lifts his handset, his uniselector US hunts for and seizes a free 1st code selector FCS and the A-digit hunter ADH associated therewith hunts for and seizes a free A-digit selector ADS. This latter switch gives access over level 1 to the manual board, over levels 2-9 to directors DS, and over level 0 to an impulse-repeater relay set IRRS. A call within the director area is set up in the normal way, over one of the levels 2-0 of the 1st code selector and possibly over 2nd and 3rd code selectors SCS and TCS respectively to one of the junctions AJ, under the control of a director DS. For a call outside the director area, the calling subscriber first dials the digit " 0," causing the A-digit selector to step to level 0 where it hunts for and seizes a free impulse repeater relay set IRRS. This immediately returns a single impulse over the connection to the first code selector FCS which is thereby stepped to level 1 where it hunts for and seizes a free register-translator relay set RTRS, which is permanently associated with a register-translator RT of the magnetic drumtype described in Specifications 717,687 and 717,690, comprising a common translator and a plurality of registers each associated with a relay set RTRS. The dialled digits are first stored in a mechanical impulse regenerator in the inpulse-repeater relay set IRRS and are then retransmitted to the seized registertranslator relay set RTRS, which is repeatedly tested by the associated register to determine whether impulses are being received. As they are detected, received impulses are stored magnetically in the register. When a full complement of exchange code digits has been stored, the register makes reference to the translator portion of the magnetic drum which provides the translation of the dialled code. The translated digits are transmitted by the register-translator relay set RTRS, the first two digits serving to set the 1st and 2nd route selectors FRS and SRS respectively to take into use an idle outgoing junction NJ over which the remaining translated digits and the numerical digits are transmitted when the distant exchange signals that it is ready to receive them. When all the digits have been transmitted, the register initiates the release of the A-digit selector ADS and the impulse. repeater relay set IRRS. Metering is con. trolled by the register from information supplied by the translator on receipt of the exchange code digits. Metering pulses are generated in the register-translator relay set RTRS and passed back to the 1st code selector FCS. The 1st code selector and A-digit selector are similar to those described in Specification 469,184. Each register-translator relay set RTRS contains gas tubes which are selectively fired in response to signals from the register, each tube bringing up an associated relay which locks itself and extinguishes the tube. The transmission of the routing digits involves the interaction of two circuits of this type.