Patent GB-521419-A (GB)
Title: Improvements relating to telephone systems
IPC: H04Q3/42
Filed: 1938-11-18
Abstract: 521,419. Automatic 'exchange system. SIEMENS BROS. & CO., Ltd., and HENSLER, B.A. Nov. 18, 1938, No. 33606. [Class 40 (iv)] A keyboard-controlled sender with means for translating the exchange name into a routing number controls local junction selecting switches by transmitting the digits in code and other switches by transmitting numerical impulses in voice-frequency or direct current form or in both forms simultaneously, the unnecesary form being suppressed in switches or repeaters. It also includes means for directing a call over an alternative route if the preferred route is busy. The operator may disable the alternative routing feature and may direct a call over a particular junction. The junctions for use in an alternative route may be special to such use and therefore normally obtainable by keying or may be the preferred junctions for calls to other exchanges. If the call being set up over the alternative. route meets congestion an attempt is made to set it up over the preferred route and if this is unsuccessful the call is stored. If the call is for a group in which delay working is in operation, the sender passes back a signal characteristic of the amount of delay. When a first selector fails' to find an outlet the sender releases and resets it. The register sender may be associated with a partially established connection and the translating and code sending arrangements are then disabled, untranslated digits being sent as V.F. impulses in accordance with the. condition of such of the registers as are set. One of the registers as well as being set by keying is set in accordance with translated digits to be sent and in some cases in accordance with untranslated digits transferred from another register. The impulse transmitting arrangement comprises a double wound self-interrupting relay similar to that described in Specification 462,773, associated with condensers which are connected up in different ways, e.g., to vary the impulsing rate when the interdigital pause is being measured from that used for controlling selectors and for speeding up the impulse rate in the case of certain translations. In the system described two stages of selectors are used for selecting the more important junctions and three stages for minor junctions. ' For calls over junctions of both these kinds use is made of latch-controlled translating switches. Calls over certain special junctions and local calls do not use the translating switches. Specification . 471,763 is referred to in the Provisional Specification. Associating register-sender with operator's position and registering keyed digits. On the operation of SA or SB in one of two chain starting circuits the appropriate one of two latch-controlled switches CSA, CSB hunts for the calling operator under control of TA which stops the switch by cutting a relay B into a latch magnet circuit. Relay B locks up and releases normally energized relays C to extend the chain circuits. Four - relay registers AW .. AZ, BW. . BZ &c. are controlled via wipers 1 .. 4 of CSA or CSB and wipers 2 .. 5 of a digit distributer DD which is stepped on at each operation of a key by a relay DS energized in series with the register relays. Preferred translations for exchanges reached over important junctions. The digits keyed are XXO where the first digit is not O and the first two are not 99. On the relapse of DS when the B digit has been keyed, TC pulls up and causes a control switch SD to race to its 17th terminals whereupon a relay ST is energized over SD4. Relay TC also completes circuits whereby the main translator consisting of two latch-magnet switches MUC, MUD permanently associated to give increased capacity and the subsidiary translator, a single latch-magnet switch MUE, hunt for a marking applied by the A and B registers via a translating frame and wipers 12, 14 of the main translator and wipers 6, 7 of the translator MUE respectively. If MUC reaches its last terminal relay SW causes the search to be taken up by MUD. The translators are stopped by the test relays TB, TD respectively. Relay TD energizes ET and when TB also is energized CT pulls up. When the C register has been set CS pulls up and the digit distributer energizes F. If the preferred route is available, PY is energized over wiper 10 of the main translator and prevents the operation of SY. Alternative translation. If only an alternative route is available, SY pulls 'up and releases TB by connecting it to wiper 13 instead of wiper 12 of the main translator, CT falls back and the translator hunts for a marking via wipers 13, 14 of the main translator and wiper 8 of the translator MUE. If MUD is driven to last terminals a releasing winding of SW is energized and the hunt is taken up by MUC. Control of, selectors for the preferred route. On the operation of CS the G register is set over the first four odd wipers of the main translators and a translating frame (not shown) and applies battery via a high speed relay TS, a relay TT and wipers 6, 2, 3, 7, of the control switch SD in position 17 to a combination of the out signalling wires W ... Z reached over wipers 6 8, 9 and 10 of CSA or CSB. Relays TS, TT remain operated until the first selector has been set and then fall back to give an impulse to DC which 'releases the register relays and causes the control switch to move to position 18 from which it moves automatically to 19. In these positions FD is operated, the G register is reset over the first four even wipers of the main translator and acode digit is sent as previously described to the second selector. When this has been set numerically the controller moves to 21, FD is released and a further code digit is sent in accordance with the condition of the C register. In the case assumed the digit is O and the second selector therefore hunts after which it causes the coritroller to move to 23 in which CO initiates the restoration and release of the register-sender. Connection to individual junction. If 1.. 9 is keyed as the third digit the alternative routing feature is disabled and the second selector is set to the junction indicated by the digit. Control of local and distant selectors for the alternative route. In this case the third digit is sent as W, X, Y instead of W, X as registered. This combination, which is never sent for direct route calls, causes the selector to hunt in a special group and prevents the storage of the call if the search is unsuccessful. When an alternative route is taken the fact is signalled to the operator who releases the register sender, the automatic operation of CO in position 23 being prevented. If the route is one involving distance switches the translator energizes relay N and when SY pulls up AD is energized also, connects the fourth contact P in banks SD6, SD2, SD3, SD7 to the wipers 1 .. 4 of the translator MUE and causes the relay SO to be operated when the control switch moves to position 22. The control switch then moves automatically to position 4. Relay SO is followed by SS, VF, S, SN, DQ, and X. By this means the W and X wires are connected to a V.F. impulsing circuit instead of to the wipers SD3, SD7 and the Y wire is connected to a D.C. impulsing circuit and an impulse generating relay A is started and sends impulses at a rate determined by the condensers associated with its second winding to relays AR, AS which repeat them over the impulsing circuit and to a counting chain CA . . CD of the kind described in Specification 471,987. Stop relay SZ is connected by the chain to marking wires from the wipers of MUE is various ways in turn and in due coursestops the digit and locks up in parallel with SR which releases SN. Relays A, AR, AS, the counting relays and DQ fall and DP is operated. Relays SN, DQ are then re-operated and A generates impulses at a different rate. These impulses only affect the counting chain and afterten of them VC pulls up and releases SN, DQ, SZ, SR, DP and the counting relays and then. falls itself. An impulse is thus given to the control switch magnet which drives the switch to position 5 in which CO releases the registersender. Transmission of preferred route code if alternative route is congested. The second selector in an " all trunks busy" position puts battery on wire Z to cause the operation of RS in position 22 of the control switch which then runs automatically to position 17. RS also releases the selector and relay ST, operates PY and then falls back. On the relapse of SY when PY pulls up the main translator hunts for the preferred route position. The preferred translation is then sent out and if the selector is unsuccessful the call is stored: Similarly if the distant selector encounters congestion it sends back a voice frequency signal to cause the operation of RS in position 5 of the control switch after the measured pause which follows the transmission of the V.F. digit and the translation for the preferred route is sent as in the other case. Prevention of alternative routing. If the operator presses a special W, X, Y key instead of the O key for the third digit, PY is held .operated and prevents the operation of SY whatever the state of the traffic. Repeated search by first selector. Whenever a first selector or, in the case of calls over minorjunctions and local calls, either of the first two selectors encounters congestion RL is energised over the wire Z, releases the selector and locks up in series with DC to prevent the automatic step of the control switch in position 18. Relay ST is released and the impulse generating relay A steps the control switch slowly round to position 17 in which the first code digit is sent again owing to the operation of RM which releases RL to enable ST to re-operate. Relay CN is now connected up in place of RL and if the selector is again unsuccessful gives a signal to the operator Calls for minor junctions. These are reached by dialling 990XX and since TC is not op