Patent GB-897677-A (GB)
Title: Improvements in or relating to circuit arrangements for selecting and establishing a free connection path through a plurality of stages of non-numerical switches
IPC: H04Q3/00
Filed: 1958-09-26
Abstract: 897,677. Automatic exchange systems. SIEMENS & HALSKE A.G. Sept. 26, 1958 [Sept. 26, 1957], No. 30884/58. Class 40 (4). In an exchange employing switching matrices of the relay, cross-bar or cross-coil type a connection between a marked inlet and a marked outlet of n switching stages in tandem is established by extending markings forward from the inlet and backward from the outlet to a central point of the stages whereat a portion of a free path is chosen, and then extending a further marking in the reverse directions to effect the selection of further portions of a free path. Corresponding to each inter-stage link of the seven stages A to G (Fig. 1) there are two pathseeking wires (Fig. 3) termed the f and g wires, which wires are commoned at marking centres such as fCm and gCm corresponding to the matrices between which the links extend. The two portions of each f wire corresponding to a link between stages D and E are connected to an AND gate such as Ude1n, the outputs of these gates being connected to a one-at-a-time selector ZLDE. The markings applied to the f wires extending from an inlet and an outlet by contacts such as 1t1j and 1z11 are extended via contacts of the unenergized holding relays of free links and the f wire marking centres to the inputs of the AND gates such as Vde1n. Decoupling rectifiers such as Gab 11 are connected in the # wires. In respect of each free path between the inlet and outlet both inputs of the associated AND gate will be marked and the gate will apply a marking to the corresponding inlet of ZLDE. ZLDE selects one of the marked inlets, thus choosing the D-E link to be used, and marks its corresponding outlet which is connected over the g wire of the chosen link to the D and E marking centres, say gDn and gE1. Each g wire from these centres is connected to one inlet of an AND gate such as Ucdnm or Uefp1, the other inlet being connected to the f wire of the corresponding link and the outlet to one inlet of further link selectors ZLCD or ZLEF. Thus if the # wire and the g wire of a C-D link or an E-F link are marked the corresponding inlet of ZLCD or ZLEF will be marked. Each of these selectors chooses one such link and the process of choosing parts of the wanted path is continued in like manner. Actuation of cross-point contacts in the selected path.-A network of actuating wires is provided corresponding to the links of Fig. 1. Assuming the contacts to be relay contacts, then at each of the points corresponding to cross-points in the matrix an actuating winding of the relevant switching relay is connected in series with a rectifier in the actuating wire network (Fig. 6). After the path shown has been selected the marker (not shown) closes contacts 2tlj and 2z11 and, the intermediate link selector contacts z1bcm1, zlcdnm, z1de1n, and z1e#p1 having been closed during the selection process, the switching relays KA1j1, KB11m, KCm1n, KDnm1, KElnp, FK#11, and KG1p1 are operated to switch through the talking circuit. In so doing these relays close contacts in the C wire network (Fig. 10) to complete holding circuits for themselves over their second (holding) windings. Arrangements are also described for use with cross-bar switches and cross-coil selectors. Specifications 688,413, 759,631, 765,929, 768,093, 797,913, German Specifications 865,474, 1,004,765 and U.S.A. Specification 2,664,467 are referred to.