Patent GB-263596-A (GB)
Title: Improvements in automatic telephone systems
IPC: H04Q3/00
Filed: 1925-07-08
Abstract: 263,596. Standard Telephones & Cables, Ltd., (Deakin, G., Polinkowsky, L., and Hatton, TV.). July 8, 1925. Automatic exchange systems.- Arrangements are provided for working between exchanges operating on different systems of non-decimal translation. In the case illustrated it is assumed that an exchange West has its 10000 subscribers grouped on a basis 5 x 10 x 10 x 20 while an exchange East is on a basis 20x25x20, both exchanges being of the reverting-impulse type. The circuits illustrated represent apparatus at West exchange, at which are situated all the special arrangements necessary for dealing with calls in either direction between the two exchanges. In the case of calls originating at West, a registercontroller, Figs. 2, 3, is seized and records the 5-digit dialled number. If the call is a local one (first digit =2) the first digit serves only to energize a relay Lor, Fig. 2, which causes the first selector to extend the call over one of its odd levels in accordance with the second digit, this and subsequent digits undergoing translation according to West notation. If the call is to another exchange on the same notation as West (first digit =3) the first selector extends the call over its 8th level in accordance with the first digit and subsequent digits are translated as in a local call. But if the call is to East (first digit =5) a relay Fxr, Fig. 2, is energized, the first selector extends the call over its 6th level in accordance with the first digit to a repeater, Fig. 4, associated with an outgoing junction to East, and subsequent digits control the repeater without translation, the translating circuits being all opened by the relay Fxr. The repeater comprises a switch IR which performs a cycle for each digit, first sending back reverting impulses to saturate a register, Fig. 2 or Fig. 3. and then opening the two-wire junction a complementary number of times, that is to say a number of times equal to the dialled digit recorded on the register. Thus the wanted number arrives at East in exactly the same form as if it had been dialled by an East subscriber. Before repeating the thousands &c. digits, the repeater sends a preliminary digit 5 corresponding to the digit that was used up by the first selector in getting to it. An incoming call from East is dealt with by a special registercontroller, Figs. 5, 6. which translates direct from East to West notation. The register-controller,. Figs. 2, 3, is similar to that described in Specifications 249,640. 257,307, consisting of 4 registers Acr, Bcr - - - Gcr, Hcr each consisting of 6 pairs of counting relays and an auxiliary pair, each register being built up to a certain point by x dialled impulses and later built up to saturation by 10-x reverting impulses from the selectors, the next reverting impulse then energizing a pair of relays Scr, Tcr to open the fundamental circuit. The first register is used to record the last as well as the first dialled digit, being released in the meantime. The selector circuits at West and the inter-controls between these circuits and the register-controlled are substantially the same as in the Specifications above referred to. The operations in calls originating at West will first be described. Recording dialled digits. When the registercontroller, Figs. 2, 3, is seized by a selector, the sequence-switch R4 goes to position 3, in which relay Isr is energized over the calling line and energizes relay Lbr. The first digit is repeated by relay Isr over cams G, H to the first register Acr, Bcr. Relay Lmr is energized during the digit and then relapses, driving the switch R4 first to position 4 and then to position 6, in which the second digit is repeated to the second register Ccr, Dcr. Similarly in positions 8 and 10 the third and fourth digits are repeated to the third and fourth registers Ecr, Fcr and Gcr, Hcr. Finally, in position 12, the fifth digit is repeated to the first register Acr, Bcr, which by this time has been released by the opening of cam M as the switch R5 leaves position 2, and the switch R4 goes to position 14. Control of selectors for local call; translation. Local calls are identified by a first digit 2, which causes energization of a relay Lor over a front contact of Acr 2, 8 and back contact of Acr 3, 9. Under control of the switch R4 the switch R5 goes to position 2 as soon as the first digit has been recorded, and relay Lor energizes relay Tcr to prevent the closure of the fundamental circuit in this position. Relay Tcr drives the switch R5 to position 3. When the second digit has been recorded the switch R4 drives the switch R5 to position 4¥ and a fundamental circuit is closed through relay Osr and through a compensating resistance which, in the case of calls to other exchanges, would be short-circuited at a back contact of relay Lor. The first set of reverting impulses is repeated by relay Osr over cams D, E to the second register Ccr, Dcr, and builds it up until all the relays are energized, when the next impulse is directed over cam R to relays Scr, Tcr. Relay Tcr opens the fundamental circuit and drives the switch R5 to position 6“. If or as soon as the third digit has been recorded, the switch R5 is driven to position 8, in which a fundamental circuit is again closed. The second set of reverting impulses is now repeated by relay Osr to the third register Ecr, Fcr and eventually energizes relays Scr, Tcr to open the fundamental circuit and drive forward the switch R5. Similarly the third set of reverting impulses is repeated in position 12 to the fourth register Gcr, Hcr. The fourth set of reverting impulses is repeated in position 14“ to the second register, the relays of which are at this time all energized or all de-energized as explained below, and if or when this register is saturated impulses of the same series are repeated over cam R to the first register. The system of translation is as follows. If the second (i.e. thousands) digit is even, relav Etr is energized as the switch R5 runs through position 3¥ over a back contact of relay Fxr and cam H, and as the switch runs through position 7# an impulse is supplied over cam G and a front contact of Etr to energize an additional pair of relays in the third register. If the second digit is odd, the relay Etr is not energized, and as the switch R5 runs through position 4# an impulse is supplied over cam C and back contacts of relays Etr, Spr, Fxr, to energize an additional pair of relays in the second register. If the third digit is even, relay Ehr is energized as the switch R5 runs through position 7 over cam I and a back contact of relay Fxr, and as the switch runs through position 7“ an impulse is supplied over cam O to energize an additional pair of relays in the third register. If the third digit is O, relay Por is energized over a back contact of relay Fxr and cam M of switch R4, and besides energizing relay Ehr causes the third register to be unlocked at cam M so soon as the switch R4 leaves position 9. The above operations have the following effects :- First selector. 2nd digit 0. 1. 2. 3. 4. 5. 6. 7. 8. 9 level 1. 9. 9. 7. 7. 5. 5. 3. 3. 1 Second selector. 3rd digit 0. 1. 2. 3. 4. 5. 6. 7. 8. 9 level (2nd digit even) 9. 9. 7. 7. 5. 5. 3. 3. 1. 1 level (2nd digit odd) 10. 10. 8. 8. 6. 6. 4. 4. 2. 2 The fourth and fifth digits control the movements of the final selector without translation, except that if the third digit is odd the selector must take 10 extra rotary steps. This is provided for by arranging that the second register Ccr, Dcr, which at the moment is fully saturated, is unlocked at cam Q as the switch R5 runs from position 8 to 9, so that the final set of reverting impulses may build up this register again to saturation before reaching the first register, but if the third digit is even, relay Ehr is energized and short-circuits the cam Q to prevent the second register from being unlocked. Call to East: translation cut out. Calls to East are identified by a first digit 5, which energizes relay Fxr over back contacts of relays Bcr 6, Bcr 1, 7. The first selector selects a junction to East over its 6th level under control of the first register Acr, Bcr. This selection occurs when the switch R5 is in position 2 (which is rendered ineffective in the case of local calls by the relay Lor) the reverting impulses being repeated by relay Osr, over cam R to the register Acr, Bcr. In subsequent positions 4 digits are sent to the repeater, Fig. 4, under control of the registers Ccr, Dcr; Ecr, Fcr; Gcr, Hcr; and Acr, Bcr. These operations proceed as described in the previous paragraph except that the relay Fxr, being now energized, opens all the translating circuits, so that the digits sent are simply the complements (11-x) of those (x) recorded on the registers. Repeater, Fig. 4, for repeating the untranslated number to the East exchange in the form of interruptions of the outgoing two-wire junction. Relay Rlr is energized over the incoming c-wire and energizes relay Asr which drives the switch R to position 2, in which battery is connected to the outgoing a-wire through cam F, relay Alr, and cam H, and ground is connected to the b-wire through cam E. Line-finders at the East exchange are set in action over the b-wire and the finding of the junction results in the grounding of the a-wire to energize relay Alr, which energizes relay Ahr, which locks itself and unlocks relay Asr. When a register-controller at East has been associated with the junction, the a-wire is momentarily opened at East to unlock relay Alr, which unlocks relay Ahr. The switch R goes to position 3 and at C drives the switch IR to position 15. The junction wires are row bridged through cam H of R, cam B of IR and cam E of R, and this bridge is intermittently opened at the cam B to send a train of impulses. At this stage a preliminary digit (say 5) must be sent, to signify to East that the call is