Patent GB-805327-A (GB)
Title: Improvements relating to automatic telephone systems and the like
Inventor: FLOOD JOHN EDWARD
IPC: H04Q3/42
Filed: 1956-01-24
Abstract: 805,327. Automatic exchange systems. SIEMENS EDISON SWAN Ltd. Jan. 24, 1957 [Jan. 24, 1956], No. 2325/56. Class 40 (4). A translator comprises a storage device, such as a magnetic drum, in which translation information is stored in serial form on both main tracks and auxiliary tracks, an auxiliary track being used when translation is required for a larger number of code digits and a main track when a translation does not exist for the larger number but exists for a smaller number of the same code digits. In a system such as described in Specification 805,326, areas are represented by three code digits and exchanges within an area by a further three code digits. Where a direct junction exists to an exchange in a neighbouring area translation is required for all six code digits, these translations being stored on auxiliary tracks. For calls to exchanges without direct junctions translation of the area digits only is required and these are stored on 100 main tracks. First embodiment, Fig. 1. In the manner described in Specification 805,326 the six digits identifying a wanted exchange are signalled from the register to a common translator over leads L1-L6 to energize appropriate relays RA-RF. Relays RA and RB select one of the 100 main tracks MH on a magnetic drum and RC selects the appropriate sector of the track whereby first and second choice translations are fed to gate G2. The register applies afresh to the translator for each translation digit required, energizing a different relay RR at each application. The operated relay RR opens gate G2 to pass the required digit in each translation and gate G3 is controlled by relay 1CR or 2CR according to whether the first or second choice is required. The required translation digit is then stored briefly on trigger circuits T1 in the manner described in the earlier Specification before being sent over .leads L10 to the register. In this case no translation is made of digits D-F. For calls to areas containing exchanges with direct junctions to the calling exchange use is made of auxiliary tracks. The first three digits in such a case energize one of a set of relays RX while the fourth and fifth digits energize one of a set of relays RDE. The relay RX selects a group of auxiliary tracks AH and RDE selects one of the group. Relay RF then selects a sector on the track so that gate G1<SP>1</SP> passes the first and second choice translations. The required digit is then selected in the same manner as for a main track but a reading from an auxiliary track sets up trigger T3 to inhibit at T1 the readings obtained from the main track. Second embodiment, Fig. 2. If there are only a few codes requiring translations for all six digits the modification shown in Fig. 2 may be used. In such cases, besides selecting an auxiliary track and the appropriate sector, the six digits control gates G6 and G7 to operate a relay K which cuts off the readings from the main tracks whereby the one set of gates G1<SP>11</SP>-G4<SP>11</SP> may be used instead of two.