Patent GB-628174-A (GB)
Title: Telecommunication systems
IPC: H04Q1/18
Filed: 1944-12-08
Abstract: 628,174. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd. (International Standard Electric Corporation). Dec. 8, 1944, No. 24604. [A Specification was laid open to inspection under Sect. 91 of the Acts, Aug. 7, 1945.] [Class 40 (iv)] In a system in which outlets from switches are characterized by different electrical conditions and in which control of the switches is effected by setting up the required condition in a register controller and causing the switch to hunt until the condition found corresponds to that set up in the register-controller, this method is used not only to set group and final selectors but also first and second line-finders. All the selectors and line finders have identical switches and relays, a simple strapping arrangement determining which of these functions the assembly will perform. Other features described are claimed in Specifications 628,176, 628,177, 628,178, 628,179 and 628,242. Specifications 558,416, 563,501, 573,405, 577,088, 592.846 and 593,687 also are referred to. General description. A subscriber on calling is given access to an " R-link " which associatesitself at one end with a 2nd finder/group selector link (or " B-link ") and at the other with a register-controller. The operation of the finders is then controlled by a thermionic testing arrangement in the register-controller. The finders and R-links are divided into half-groups, each of which is first choice to half the 100-line group but can be used by the other half. The register-controller is adapted for use in a system in which both two-digit and three-digit office codes are employed and in accordance with the office digits received takes into use a two-digit or three-digit translator. Local switches are controlled by the multi-potential marking method, the register controller changing its circuits when an outgoing junction is seized so that it sends subsequent digits as impulses over the loop. Arrangements are provided whereby an additional two digits may be registered and re-transmitted for controlling switches in a P.B.X. Ringing, metering and coin collection are controlled from the R-link. Release is controlled from the 2nd finder/1st selector link, but a relay is provided in the final selector to delay its release for an appropriate period if the called party fails to hang up. Apart from this relay and the relays concerned with holding the connection in the finder/selector link, each numerical and non-numerical switch has only two relays, a relay BR which operates when the switch is seized and a relay AR which controls the driving circuit under control of the registercontroller. First and second finders. When a subscriber calls, his line relay LR, Fig. 4, puts the calling potential PC in place of the numerical potential on his T-terminal in the first finders, Fig. 2C, and energizes USR or LSR in the starting and allotting circuit according as the -subscriber is in the upper or lower group of 50 lines. USR or LSR over wire X energizes the starting relays LSR in all the appropriate R-links, Fig. 6, i.e. circuits for associating an idle register-controller with an idle second finder/first selector circuit. Switches in these circuits then hunt, first for a finder/selector circuit under control of T1R, T2R and then for a register-controller under control of T2R, T3R and T4R. When an R-link is thus prepared, it energizes the power magnet .n the allotting circuit, Fig. 5. When the allotter reaches a prepared link, T1R; T2R pull up and the starting relays LSR, Fig. 6, are released. In the register-controller, Figs. 10, 10a, 10b, RAR pulls up in the test circuit, energizes HTBR and connects up the testing tube V2A. Operation of the allotter test relays is also followed by that of LAR in the R-link. BAR, BBR and the relays BR of the second finder and the associated group selector were energized when the R-link relays T1R, T2R operated and, on the operation of LAR, a circuit is made for RFR in the register-controller in series with AR of the second finder via the a-wire. AR then completes the driving circuit and the switch hunts over the T bank for a potential equal to that characteristic of the calling group which has been applied to the grid of tube V1A in the register-controller from the allotter circuit. The T wiper is connected to the grid of V2A via the b wire and consequently when an idle first finder of the required group is reached, the associated gas-filled tube GV1 fires and GVR1 releases AR in the second finder which then stops and switches through, energizing BR in the first finder, Fig. 2C. GVR1, Fig. 10, energizes GSR1 which releases HTBR to extinguish the tube GV1. GVR1 then falls followed by GSR1 and ground is replaced on the a wire to operate AR in the first finder which then hunts in a similar manner to the second, but under the control of V2B, V1B, GVR2, GSR2. The last mentioned energizes RBR which releases RAR and operates LBR and releases T3R, T4R, T1R, T2R in the R-link. Cut-off relay COR operates over the c-wire, and the allotter is released. The subscriber's loop is now connected through to DR, Fig. 10, over the dialling tone transformer DTC and DR energizes R1R. LBR also operates BER, Fig. 7, which releases BAR but holds and energizes BRR. 2nd choice links. The R- and B-links may serve any of the lines 1-100 but are each divided into two groups, one group being first choice for lines 1-50 and the other for lines 50-100. If, however, all R-links appropriate to one group are busy an energizing circuit for the start relay USR or LSR of the 2nd choice group is made over series contacts of LCR or LBR in all the busy R-links of the first choice group. In the banks of the B-link finders only the T-terminals appropriate to the first choice links are normally connected, but if all these links are busy a series circuit over contacts of the BRR relays operates UBR which connects up the T-terminals of all the second choice links. Code translation. The digits are repeated to registers D1 ... D6 or D7 via a distributer PI controlled by a series relay R2R. The first operation of the latter is followed by that of RDR, RER which lock up. When the first digit has been registered, RTR1 is operated, except in the case of certain first digits, and energizes a common starting relay CSR1 which energizes individual starting relays TSR in all the idle two-digit code translators, Fig. 11. The finders of these then hunt for the calling register controller and T1R in the successful one stops the finder and shunts out CSR1 to release the others. When the second digit begins to come in, TAR, Fig. 11, is operated over the G-circuit in series with RTR3 which remains unoperated, and releases TNR (previously energized by TSR), the relapse of which completes a circuit for the translating switch magnet P2. The latter is stopped momentarily by GVR (which co-operates with a pair of vacuum tubes V1, V2 and a gas-filled tube GV) when the potential encountered on terminal by wiper T1 agrees with that connected to tube V1 over the A-wire from the A-register. GVR is followed by GSR and TER which locks and substitutes a marking from the B- register. GSR, GVR then fall, TFR pulls up and the translator is again driven. To enable the same potentials and the same marking bank to be used for the A-marking and B- marking operations, the so-called permanent markings are normally applied only to terminals 1, 11, 21... the others being connected up by relays PNR on the operation of TER. Each of such relays connects up the nine potentials other than the potential connected to the first terminal of the corresponding group. On reaching the selected B-digit potential, the switch is stopped by TCR which is followed by TBR and TFR, TER fall back. Assuming that the code dialled is a two-digit one, the shunting by TCR of the high-resistance winding of TAR allows RTR3 in the registercontroller to come up and release RTR1. Five connections from the translater wipers now extend over the wires A ... E to terminals of the out-control switch PO and to relays RTR4, RTR5 which control the skipping of positions by the control switch in accordance with 'the number of digits in the routing code. If the A and B digits are those of a three-digit code, the translator switch picks up a ground on its terminal T2, TDR operates in series with RTR2 in the register-controller, TAR is released to free the two-digit translator and the common starting relay CSR2 is operated to cause the association of a three-digit translator, Fig. 13. When the 3rd digit begins to come in, TAR, Fig. 13, is operated in series with RTR3 (which remains unoperated at this stage) and the translator hunts with its wiper T1 for a position in accordance with the A- digit and then with its wiper T2 for a position in accordance with the B and C digits, the sequence being looked after by relays TER, THR. Finally, TCR energizes TBR and shunts the high-resistance winding of TAR to operate RTR3 in the register-controller. Control of selectors by register-controller. RTR3 connects ground via wiper B of the outcontrol switch PO in position 1 over RFR and the f-wire to the a-wire of the first selector Fig. 2b, AR therein pulls up and starts the switch and RFR energizes RGR in the registercontroller. When the T-wiper, which is connected over the b-wire of the switch and the g-wire of the R-link to the grids of tubes V2B, V2A, encounters the same potential as that applied to the grid of V1A from the A-wiper of the translator, GV1 fires and GVR1 stops the switch by interrupting the circuit over RFR to the a-wire. The seized line is marked non-selectable instantly by the alteration of potential of the T-wiper due to the firing of GV1. RGR falls on the relapse of RFR to remove the marking potential from VIA and GSR1 extinguishes the tube GV1 and gives an inpulse to the out-control switch. Subsequent group selectors, Fig. 2a, are controlled in the