Patent GB-1383040-A (GB)
Title: Telecommunications exchange systems
IPC: H04Q3/54
Filed: 1972-09-22
Abstract: 1383040 Automatic exchange systems SIEMENS AG 22 Sept 1972 [24 Sept 1971] 43905/72 Heading H4K In a programme controlled exchange in which the peripheral equipments are arranged in groups each containing line circuits, relay sets, digit receivers and a folded switching network, the latter is composed of bi-stable remanent relays which are not released at the end of a call but instead are released just prior to the setting up of another call via a crosspoint which lies in the same column or row. The organization of the exchange follows the sectionalization practice disclosed in Specification 1,205,306 where a plurality of equipment groups AF (Fig. 1) are buffered via interface units AS and microprogramme devices BS over data buses U2 to duplicated central controls ZS which make use of duplicate programme stores PS and a single call store ZJS. The latter contains a memory map for path finding purposes. The result of a path finding operation in terms of network input and output and the intervening A, B and C switches that are to be used is transmitted as a 6 digit word to the relevant microprogramme device BS so that instructions for cleaning the crosspoints adjacent the chosen path and then for setting up the path may be transmitted to the relevant network control circuit ST. It may be noted that an equipment group includes a number of switching sub-networks KGV, Kt which have control circuits STv, STt therefor which are independent of the circuit ST used for the main network KG/KT. The latter is a conventional folded network having one path between any A stage inlet and C stage outlet, the precise grouping of A and B switches KG1 &c. and the trunking to sets of C switches being depicted in more detail in Fig. 4 (not shown). Full accessibility to other equipment groups is provided by links ZLC (Fig. 3, not shown). Setting-up a connection.-The central control conveys the chosen path identity and a start signal to a mioroprogramme device BS which repeats the identity to the relevant control circuit ST where it is recorded temporarily, preferably on remanent relays so that BS need not keep sending the identity with each subsequent control command. The first such command is effective to restore every remanent crosspoint relay in the column of crosspoints in the chosen matrices of each stage. The restoration may be effected stage by stage or simultaneously in all stages. Fig. 5 depicts a typical switching matrix in which it is assumed that crosspoint relay K12 is to be operated. In the control circuit ST2 the path identity results in the operation of row select contact z1 and column select contacts 1s2, 2s2 (these contacts could be common to a plurality of switches as disclosed for example in Specification 1,227,056). The "clean column order" from BS results in the actuation of contacts 23, 24 whereby positive potential is extended via all the unmade row select contacts such as zn to those relays such as Kn2 which occupy the selected column having contact 2s2 closed and thus its diodes, e.g. Gpn2 forward biased. All such relays which are not already released now do so thereby opening their speech wire contacts. Sufficient time is allowed to elapse in order to complete this order whereafter a "clean row order" is given. Contacts 23, 24 open while 13, 14 close. This time positive potential is applied only to row wire zz1 but from there it spreads to all columns except the selected one so that any operated row relays K11 to K1m may release. After a determined time, the control device opens contacts 13, 14 and closes contacts 43, 44 thus conveying the "final set-up order" which is effective to actuate (if it is not already so actuated) relay K12 via diode Ge12. The above procedures take place in all the stages controlled by the particular ST circuit so as to connect through the calling A inlet to a chosen C outlet. If a lesser number of stages are required the control circuit copes accordingly. When the path is set up all the control circuits withdraw.