Patent GB-739905-A (GB)
Title: Improvements in or relating to telecommunication systems
Inventor: CORNER ARTHUR CHARLES
IPC: H04Q3/00
Filed: 1952-05-24
Abstract: 739,905. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. May 11, 1953 [May 24, 1952], No. 13216/52. Class 40 (4). In order to set up a connection from one of a first group of points to an idle point of a second group over a plurality of switching stages the said one point is marked and the marking is extended over available routes to idle points of the second group, and subsequently a signal is repeated from stage to stage from an idle point of the second group over one available route to operate the switching devices to complete the connection from said idle point to the marked point. This method of setting up a connection is particularly applicable to cross-bar systems and is used for connecting a calling line to a connecting circuit associated with a register controller and connecting the connecting circuit to a called line, the marking being applied to the calling or called subscriber's line. 10,000-line exchange using 10 x 20 cross-bar switches. The subscribers' lines are in subdivisions of 400 served by 20 primary switches PG1 ... PF20, Figs. 2 and 3, and 10 secondary switches SF1 ... SF10, each primary switch being connected to all 10 secondary switches. The outlets of each secondary switch are connected to 5 in-trunks IT and 5 out-trunks OT and the out-trunks are graded to connecting circuits TO which are in groups of 10. All the connecting circuits of a group are marked busy when the two associated register-controllers are in use. Incoming junctions are connected directly or over preselectors WP to certain groups of connecting circuits and are busied at their incoming end when no register-controller is available. Each group of connecting circuits is connected to the inlets of a separator SEP1 ... SEP6, Figs. 4 to 6, having local and junction outlets. The local outlets of the separators are graded into groups of 100 trunks, each group being connected to 10 divisional selectors 1DIV1 ... 1DIV10 which form a section LS1. The outlets of a section of divisional selectors give access to 5 groups of 40 trunks, each group being connected to 4 outlets of each divisional selector. Groups of trunks from two adjacent sections are paired and each pair leads to the inlets of a division DIVE of 8 sub-divisional selectors ESDIV1 ... ESDIV8, each group of each pair giving access to 5 inlets of each of the selectors ESDIV1 ... ESDIV8 in the division. The outlets of a division are formed in 5 groups of 32, comprising 4 from each of the 8 subdivisional selectors ESDIV1 ... ESDIV8. Each group of 32 together with the corresponding groups from divisions A ... DSDIV1 ... 8 reached by other pairs of sections are graded into the 50 in-trunks IT connected to the secondary switches SF of a sub-division. The separators SEP1 ... SEP6 also give access to junction sections each consisting of 10 primary switches JPS1 ... JPS10 and 20 secondary switches JSS1 ... JSS20. Each separator has access to only one junction section and one local section. One marker is allotted to each subdivision of lines. In setting up a local call the register controller marks the required subdivision in the sub-divisional selectors accessible from the section in use. A register-controller having marked a free line and failed to set-up the call re-marks after 3-6 seconds to make a second attempt and if this fails reverts busy tone. Connecting caller to connecting circuit. Assuming subscriber SL1 connected to primary switch PF, Figs. 8, 9, 10, calls, line relay 1L operates a selecting relay 1PSR associated with the pair of subscribers SL1, SL2 and PRA associated with the odd-numbered subscribers. Relay PRA energizes a magnet 1PAM to connect the odd group of contacts to the outlets P1, 1-P1, 10. 1PSR disconnects the holding circuits of all higher numbered selecting relays and PMKA, PMKB open the energizing circuits of the selecting relays. Thus if two subscribers connected to the same primary switch call simultaneously only the lower numbered selecting relay remains operated. 1PSR energizes a selecting magnet 1PSM. According to the class of the caller, i.e. coin-box, normal, or trunks barred, lead T1 is strapped to lead T2, T3 or T4 so that one or both of relays PCX, PCY operate to earth leads MX, MY of all the outlets and PM follows to apply battery over the leads M of all free outlets to inlets such as SO1 in a number of secondary switches SF such as shown in Figs. 11, 12. The marking on lead M energizes a selecting relay 1SSR which operates a selecting magnet 1SSM and relay SRA followed by the oddnumbered group magnet 1SAM. Relays SMKA, SMKB disconnect the energizing circuits of the selecting relays and chain holding circuits ensure that only the lowest numbered operated selecting relay remains up. Relays SCX, SCY operate in accordance with the class markings on leads MX, MY, whereupon OC, OK connect the test relays TA ... TE to the leads M of the out-trunks SOT1 ... SOT5. Supposing the out-trunks SOT1 and SOT5 are free TA, TE operate to release OC and OK. TA opens the circuits of all higher test relays such as TE and holds over lead MH. If more than one out-trunk has access to the same connecting circuit it is arranged that only one test relay can hold to the lead MH or operate over lead M. The call has now taken into use up to 10 outtrunks and one of these is seized by means of a circuit extending from lead IS1 over back contacts of the test relays and lead OS1 to lead IS1 of the next secondary switch and so through all 10 secondary switches serving the subdivision. 5 equally-spaced tappings on this circuit are taken to a start shift circuit so that when a relay OC operates and lead ST is earthed, the start shift circuit earths one of the tappings and this earth is extended over the first operated contact of a test relay to a lead RCM pertaining to the chosen out-trunk SOT1. When all the relays OC release the earth is disconnected by the start shift circuit which, when the next call occurs or when through, say, a fault no test relay holds and a relay OC reoperates, earth the next tapping so spreading the traffic. If, due to a fault, earth is maintained on the common start lead, the start shift circuit earths each tapping in turn. When the connecting circuit is seized it earths lead P of the out-trunk OT to energize the operating magnet 6SBM corresponding to the outlet SOT1. The magnet 6SBM extends forward the class markings over leads MX, MY and backward the earth on lead P whereupon the appropriate operating magnet, say 1PBM of the primary switch PF, switches through the line wires and removes the battery marking on the lead M to release in the secondary switch all relays and magnets except the operating magnet. In the primary switch, cut-off relay 1K holds in series with 1L and the wire P and releases all the other relays and magnets excepting the operating magnet. Seizure of connecting circuit, Figs. 14, 15, 16, and register-controller. The relays below the dotted line are common to 10 connecting circuits RC1 ... RC10, RC1 being shown in detail and the lower half of Fig. 15 showing elements of all 10 connecting circuits. Supposing one of the register-controllers REG1 is free and the other busy, earth is applied from REG1 over lead RM1 to all leads RH3 in series so operating relays RMA, RCMA. Relay RMA applies battery to the incoming leads M of free connecting circuits. When earth is applied from a secondary switch SF to lead RCM, relays RCA, RCB connect up the register-controller REG1 and release RMA, RCMA which disconnect the idle marking of all the connecting circuits of the group and which if REG2 has become free connect up the corresponding relays RMB, RCMB to re-mark the free connecting circuits. Relay CA disconnects the incoming wire M. Local call. The register-controller REG1 earths lead MP1 to operate MPA which connects the control leads from REG1 to the associated separator and disconnects MPB so preventing the other register-controller REG2 from setting up a call at the same time. The marker of the wanted sub-division is taken into use and marks lead MR of, say, subscriber SL2 whereupon the primary switch operates as for an outgoing call excepting that, since the line relay 1L is back, relays IA, IB operate in place of PCY, PCX to apply battery to the leads MI. In any secondary switch the operation is similar to that for outgoing calls excepting that a circuit is completed over lead MI for IC which marks the leads M of free in-trunks SIT1 ... SIT5, and disconnects OC, OK. The marker marks the wanted sub-division in that division of sub-divisional selectors SDIV which can be reached both from the section corresponding to the seized connecting circuit and the called line SL2. Supposing that the section to be used is odd-numbered, the marker marks in each of the 8 sub-divisional selectors, Figs. 21, 22, one of the odd wires OSM, say 1OSM, whereupon MA connects up the selecting magnets SDSM of the outlets SDO1 ... SDO4 and OM disconnects the even wires ESM. When battery arrives over leads M from the secondary switches SF, one or more selecting magnets SDSM operate, followed by relay SDMK which ensures that only the lowest numbered selecting magnet, say 1SDSM, remains up. Group selecting magnet 1SDAM pulls up and relay MKO follows to mark the leads M associated with free links to the divisional selectors which function in a manner similar to the secondary switches to extend the markings to the local outlets LO 1 ... LO10 of the separator, Figs. 17, 18, used for the call. The marking leads of the local outlets have been connected up by relay ML energized over lead ML from the register controller REG1 which also marks lead SA or SB on alternate calls to connect up one of two starting points of the selecting magnet chain holding circuit. Relay ML operates group switching magnet 1SEAM. Relays SEM, SEMKB, SEMKA operate and selecting magnet, say ISESM, holds so that earth is extended over lea