Patent GB-1181204-A (GB)
Title: Automatic Telecommunication Switching Arrangement
IPC: H04Q3/00
Filed: 1968-01-18
Abstract: 1,181,204. Automatic exchange systems. INTERNATIONAL STANDARD ELECTRIC CORP. 18 Jan., 1968 [24 Jan., 1967], No. 2697/68. Heading H4K. In an exchange system comprising a switching network which is controlled by a route simulating network, path finding is effected, by marking all the paths between an inlet and all the outlets pertaining to a required direction, selecting one of the thus marked outlets and then selecting a single path between the inlet and this outlet. Marking detectors associated individually with each outlet are connected in a lock-out chain, whereby selection of a single outlet occurs automatically when the markings reach the outlet side of the network. Particular description. Trunking and layout.- Fig. 1 depicts the trunking between three groups of four junctors CC1A1-CC3A4 and four groups of five trunk circuits TC1B1-TC4B5 via two stages of respectively three, 4 x 4 matrices and four, 3 x 5 matrices. The trunks TC1B1, TC2B1 . . . TC4B1 correspond to a same direction as denoted by the final digit. The cross-point relays are arranged as in Figs. 3 and 4 where O1r- O16r, P1r-P16r and Q1r-Q16r are respectively relays in the LA, 2A and 3A matrices, while R1r-R15r and U1r-U15r are the relays in the 1B and 4B matrices. Operation, Fig. 2.-A calling junctor CC1A1 is connected via connector RCC to a register RC and then, when dialled digits have been received, to a translator TC where a start relay Str is brought up. One of five directional contacts d1-d5 is closed in dependence on the translation, whereby battery is extended to those detectors, e.g. 1L1, 2L1, 3L1, 4LL which correspond to the trunk circuits for this direction. In addition relays 1A1r and 1Ar (which correspond respectively to the row of crosspoint relays 01r-04r (Fig. 3) to which CC1A1 has access and, to the cross-point matrix 1A) are energized by the actuation of Str. Busy links and trunks are indicated by opened contacts 1a1b2-3a4b2 and 1b1C-4b5b respectively. Thus, if links 1A3B and 1A4B (Fig. 1) are busy, contacts 1a3b2 and 1a4b2 are open, whereby an earth marking can only be extended via 1a5 to detectors 1L1-1L5 and 2L1-2L5. Of the latter, only 1L1 and 2L1 have been marked by battery from the translator and furthermore as all the detectors are connected in a lock-out chain, only 1L1 say will become operative to operate its (not shown) relay 1L1r. Closure of the latter's contact 1l14 (Fig. 3) in series with contact 1a11 (1A1r in the control circuit CC is already up) allows cross-point relay 01r and link busy relay 1A1br to energize in series and to self hold to earth in the junctor CC1A1 (w1 was operated when CC1A1 first called). With relays 1A1br (Fig. 3) 1Ar (Fig. 2) and 1L1r (Fig. 2, c.f. detector 1L1) all energized, crosspoint relay R1r and trunk busy relay 1B1Cr (Fig. 4) are brought up to complete the connection between the junctor CC1A1 and the selected trunk circuit TC1B1. Thereafter Okr in the translator (Fig. 2) comes up to release Str and thus clear all the control circuitry. In a three-stage network (Figs. 5-8, not shown) in which there are four possible paths between each inlet and outlet, detectors similar to those specified at 1L1-4L5 in Fig. 2 are used for selecting an idle outlet in the required direction and then detectors identical with 1L1-4L5 are used for determining a single path to this outlet. The possibilities of having more than one outlet from a same switch in a same direction and of there being more than one link between two switches in adjacent stages are discussed, the necessary additions to the route finder for accommodating these cases being briefly mentioned.