Patent GB-897676-A (GB)
Title: Improvements in or relating to circuit means for selecting a connection path extending through an arrangement of switching stages
IPC: H04Q3/00
Filed: 1958-09-25
Abstract: 897,676. Automatic exchange systems. SIEMENS & HALSKE A.G. Sept. 25, 1958 [Sept, 26, 1957], No. 30694/58. Class 40 (4). In a switching system employing switching matrices in which connections are set up between marked inlets and outlets, at least in the case of the inlet side or the outlet side a plurality of inlets or outlets are marked simultaneously, a path is selected between a switch in the first switching stage having at least one free marked inlet and one in the last switching stage having at least one free marked outlet, and the inlet and/or outlet to be used for the connection is then chosen from the plurality of inlets and/or outlets marked, all free paths between the marked inlet(s) and the marked outlet(s) being taken into consideration in choosing the inlet and/or the outlet to be used for the connection. Fig. 1 shows the trunking arrangement of a three-stage switching system and Fig. 3 the associated path seeking network, having wires, such as Wab11, corresponding to the links, such as Zab11. The path seeking wires are commoned at points, such as WA1, which correspond to switching matrices, such as A1 It is assumed that a connection is to be set up between the inlet T1j and one of the outlets Z11 . . . Z1n and Zm1 . . . Zmn, in consequence 174 of which the contacts tlj and z11 . . . z1n, zm1 . . . zmn are all closed to mark the inlet and outlets. The contacts such as bab11 corresponding to free links are closed by relays (not shown) included in the busying wires of the links. The marking potential + U applied to tlj is thus extended over path seeking wires corresponding to all free links to which the inlet T1j has access to the path sections WB1 to WBk of switching stage B, and thence over wires corresponding to free links between stages B and C. Similarly + U is extended via the path sections WC1 to WCm and wires corresponding to links between the stages B and C. The path seeking wires are split between path sections WB and WC and are terminated on coincidence circuits such as Ubc11, and for each wire which is marked from both the inlet and outlet sides the corresponding coincidence circuit will apply a marking to the relevant input of the intermediate link selector ZLBC/KVC. This selector marks an output corresponding to one of its marked inlets, thus indicating the intermediate link to be used for the connection, say Zbcm1. This also determines the C stage matrix to be used, viz. that, Cm, in which Zbcm1 terminates. The location selector PKVC then selects the outlet to be used, the outputs from ZLBC/KVC and the outlet contacts z11 . . . zmn being connected via coincidence circuits U11 . . . Umn to the inputs of PKVC, those outlets of ZLBC/KVC pertaining to intermediate links terminating in the same C stage matrix being commoned. In the case under consideration the coincidence circuits Um1 . . . Umn are marked at one inlet due to the selection of link Zbcm1, and at the other as a result of the marking of the outlets Zm1 . . . Zmn. The selector PKVC chooses one of these outlets and the path may then be set up. An arrangement in which a plurality of both inlets and outlets are marked is described with reference to Fig. 4 (not shown). The matrices may comprise cross-bar switches, as described in Specification 759,631, cross-coil selectors, as described in Specification 797,913, or relays. Specifications 688,413, 768,093, 897,677, U.S.A. Specification 2,664,467 and German Specification 865,474 also are referred to.