Patent GB-307369-A (GB)
Title: Improvements in automatic or semi-automatic telephone systems
IPC: H04Q3/42
Filed: 1927-11-02
Abstract: 307,369. Standard Telephones &. Cables, Ltd., (Deakin, G., Polinkowsky, L., Stevens, G. E., Vriendt, C. de, and Liebkind, G.). Nov. 2, 1927. Automatic and semi-automatic exchange systems; metering.-A system is described employing link circuits each comprising a second line finder, a group selector, and a hunting switch for connecting up a register-controller of the code-translating type. When repeated metering is necessary, dependent on the zone of the wanted exchange, a relay or relays in the link circuit are energized from the register-controller and, upon release of the connection, cause a multi-metering finder to be connected to the link circuit to send the appropriate metering impulses. In the case of a local call, metering is effected from the link circuit, and means are provided for preventing metering in various circumstances. Extension of call to link circuit (Fig. 2), and seizure of register-controller. The first line finder (Fig. 1) makes connection with the calling line in known manner, and test relay Ltr energizes, connecting up relays Lhr, Csr, Dsr, the first of which connects in the low resistance winding of relay Ltr. Relays Cs1r, Bsr pull up, and relay Nmr energizes in each idle link circuit and connects up finder magnet PF. Test relay Gtr energizes when the marked line finder is reached, and connects in its low resistance winding in series with relay Shr, which connects up relay Pgr, releasing relay Nmr to ground the test circuit, over which switching relay Ler energizes in series with relays Lhr, Cor. Line relays Asr, Bsr energize, and sequence switch R advances to position 3, in which relays Pgr, Gtr, Shr fall back. Magnet RC operates to find an idle register-controller and when this is found, test relay Gtr energizes in series with relay Tpr, Fig. 3. and relays Shr, Pgr pull up as before, moving sequence switch R to position 4. Relay Asr is now held over wiper e. Registration of wanted number; translation. (Figs. 3. 4, 5). Relay Tpr connects up relays Sfr, Str, Kcr, and sequence switch R4 advances to position 2, when relays Sfr, Str fall back, and then to position 3¢. In position 2, impulse relay Isr, energizes over the calling loop and wipers a, b, and dialling tone is sent, while in position 3, relays Lbr, Rlr, Ocr pull up, and the last relay locks. The first train of impulses are repeated by relay Isr to magnet SA of the first register in parallel with sluggish relay Lmr which disconnects relay Ocr at the first impulse. Relay Csr connected in parallel with the interrupter springs ensures a full step of the magnet SA. Relay Lmr falls back at the end of the train, and advances sequence switch R4 to position 4¢, in which relay Ocr re-operates, and the second digit is recorded on the second register SB. In the same way the third, fourth and fifth digits are recorded on the registers SC, SD, SE in positions 5¢, 7 and 8. The digits corresponding to the desired exchange are translated into a routing number in the manner described in Specification 207,725. In position 5¢, the translating switches are started, and one of them CT stops when wipers y, z find the terminals marked in banks b of the registers SA, SB, relays Ttr, Tar then energizing. The remaining' translating switches move on to normal, when the corresponding relay Ttr energizes over wiper z, but relay Tar is short-circuited over wiper x. In position 7 of R4, after the third digit has been registered, relay Ttr is de-energized, and the translating switch CT advances again until wiper x finds the terminal marked in bank b of the register SC. Relays Ttr, Tar pull up again, and sequence switch R5 moves to position 2. Relay Dsr energizes, and the registers SB, SC are stepped to their second normal positions, and subsequently record the last two digits in positions 9, 10 of R4. Control of selectors; release of register-controller. In position 2 of R5, relay Glr energizes in the fundamental circuit over wiper d in series with relay Dsr, and advances sequence switch R to position 5, in which trip spindle magnet P2 operates, reverting impulses being repeated by relay Osr over relay Rfr, wiper w of the translating switch CT, distributing frame to the counting relays, which operate in the usual manner until relays TcrO, ScrO finally energize and open the fundamental circuit. Sequence switch R advances to position 6, in which hunting for an idle trunk takes place. The exchange routing number may comprise four digits, which are effective in positions 2, 3, 5, 7 of R5, and if the full four digits are not required, some of these positions are, skipped by means of crossconnections of cams L, M, O, Q to bank s of the translating switches. Assuming only one translated digit is employed, relay TcrO is maintained over cam O between positions 3 and 8, and sequence switch R5 is advanced from position 2 to position 9. In the link circuit, magnet P1 operates in position 6, and when an idle trunk is found, test relay Gtr energizes, connecting in relay Shr and its low resistance winding, and connecting relay Csr to the a wire. Relays Pgr, Glr advance sequence switch R to position 8. The fundamental circuit is now closed at the next elector, and reverting impulses are repeated to the counting, relays over wiper d of the register SD. The remaining digits are effective in a similar manner in positions 11, 13 and 15¢ of R5. , If, on account of non-decimal translation, the units digit requires more than ten impulses to be sent, the counting relays are used twice, under the control of relays Ecr, Edr. Sequence switch R5 advances to position 18, and relay Asr in the link circuit falls back and drives sequence switch R to position 10. Relay Isr falls back, disconnecting relays Lbr, Rlr and - advancing sequence switch R4. The registers and translating switch restore to normal, and relay Wnr pulls up in position 18 of R4 provided all the translating switches are in normal position and drives sequence switch R4 to position 1. When relay Tpr is disconnected in the link circuit, relays ScrO, TcrO energize and advance sequence switch R5 to position 1. Completion of connection; release; metering. Relays Asr, Bsr energize over the calling loop in position 10 of R, while Csr energizes over a bridge at a succeeding selector, and advances sequence switch R to position 11. Ringing takes place, and when the called subscriber replies, the bridge is momentarily broken, and sequence switch R advances to position 14, in which conversation takes place. Between positions 12 and 14, the current over the calling loop is gradually reversed at cam Q. Release by the calling party disconnects relays Asr, Bsr, Csr, and in the case of a local call, sequence switch R moves into position 16, in which booster metering battery is applied to the test circuit. Magnets P2, P1 restore in positions 17, 18. If only the called party hangs up, lamp GSL lights. Busy condition. A busy signal is sent back from a succeeding selector in position 11 of R, and upon release when relays Asr, Bsr, Csr fall back, relay Nmr energizes to prevent metering. Special calls involving 2 digits only. The first digit is of a particular value, and in position 5¢ of R4 after the second digit has been registered, a circuit is closed over bank a of register SA for moving sequence switch R4 to position 7, in which relay Str energizes over cam Q and wiper s of translating switch CT and advances sequence switch R4 to position 12. Sequence switch R5 is then advanced and the selectors are controlled as already described. Calls to call indicator position. Relay Cir energizes over cam M, and holds open the fundamental circuit until sequence switch R4 is in position 8, that is, until the first numerical digit has been registered. Thus the selection is held up at the selector preceding the call indicator in order that the full number to be indicated is set up as quickly as possible. Special service calls. The circuit of relay Csr is not interrupted on reply, and conversation therefore takes place in position 11 of R, and relay Nmr energizes on release to prevent metering. In the case of operator-hold, ground fed back over the b wire maintains relay Csr energized. False calls (no impulses received). Relay Ocr in the register-controller starts time alarm TA, and after an interval, relay Pgr energizes, opening the impulse circuit, grounding wiper b and releasing relay Asr in the link circuit. Sequence switch R moves to position 7, and thence by means of relays Glr, Pgr to position 15, in which the false call finder (Fig. 6) is started, battery being connected to wiper e of the second line fnder. When the link circuit is reached, test relay Ftr pulls up and connects in its low resistance winding through relay Shr. Relay Fer, Csr energize, starting time alarm TA and extending the a and b wires to relay Asr and the jack of the false call desk. In the link circuit, relay Ler is short-circuited, relay Nmr energizes to prevent metering, and relays Asr, Csr relapse to release the link circuit. Relays Ftr, Shr fall back when this occurs. Lamp FAL flashes, and when the operator plugs in, relay Str energizes and holds relay Asr locally. Relay Aor pulls up and lights lamp FAL steadily. The line may then be tested. If no false call finder is available, the link circuit remains in position 15 of R, and lamp PGL lights. Faulty link circuits. If the normal progress of a call stops after the digits have been registered, ground is applied at the register-controller after an interval over wiper e to energize relay Nmr, which opens the test wire, releasing the calling line and starting another link circuit. If relay Asr fails to energize, sequence switch R is advanced to position 3 by a timing device, and relay Nmr energizes with similar results. Premature release. If the subscriber hangs up before a register-controller has been seized, that is in position 3 of R, relay Nmr energizes, opening the test c