GB1101588A - Improvements in or relating to apparatus for use in telecommunications exchange systems - Google Patents

Abstract

1,101,588. Automatic exchange systems. SIEMENS A.G. 7 Sept., 1965 [7 Sept., 1964], No. 38083/65. Heading H4K. In an exchange system including a route simulation network for route selection through a switching network which is provided with more than one link between each pair of coordinate switches in adjacent stages, the process of route selection involves two steps the first of which results in the selection of a single switch in each stage and the second of which results in the selection of a single link between the chosen switches in each stage. If the switches of each and every adjacent stage are connected by more than one link, then the step of link selection takes place simultaneously in all of them. The system is applicable to the case where a fully-equipped exchange is provided for less than the theoretically possible full number of subscribers. The system is exactly the same as that described in Specification 1,077,679, but the claims relate to the feature of two step route selection. Particular description, Fig. 8.-The process of " switch selection " occurs as described in the above mentioned Specification. Each of the simulations of the links incoming to a same switch are multipled at the marking centre e.g. WK 311<SP>1</SP> via a respective auxiliary relay Lh viz relays Lh 3, Lh 4, Lh 5, and Lh 6 for the four links between a switch in the B stage and a switch in the C stage. These relays are connected through a chain consisting of their own contacts and the contacts of the link busy relays to the marking centre e.g. W.K. 211<SP>1</SP> of the proceeding stage. In operation, the marking signal reverted from control circuit ES, after the switch selection process, brings up those relays Lh which correspond to first free links whereby the relays Lh of lower priority are disconnected from the chain and the corresponding speech path relays C<SP>1</SP>, B<SP>1</SP> &c. are energized over their operating windings II. In response to the operation of these relays C<SP>1</SP>, B<SP>1</SP> &c., the link busy relays come up so as to release the simulation path through relays Lh and hence release the common equipment.