Patent GB-696953-A (GB)
Title: Improvements relating to telephone systems
Inventor: HENSLER BERNARD ANTHONY
IPC: H04Q3/42
Filed: 1950-08-04
Abstract: 696,953. Automatic exchange systems. SIEMENS BROS. & CO., Ltd. Aug. 3, 1951 [Aug. 4, 1950], No. 19547/50. Class 40 (iv). A register-translator is taken into use for setting up a connection over an alternative route only when all outlets in the direct route are busy, an outlet is available in the alternative route and delay working is not in force for the direct route. The selectors are motor-driven uniselectors having control circuits each common to a group of selectors selected by a particular digit. Before a selector giving access to direct and indirect routes makes a search, the associated common control circuit receives from the storage equipment appertaining to the routes the information determining whether a register-translator is to be taken into use. The storage equipment may be similar to that described in Specification 654,848. If after a register-translator is seized the last free outlet in the indirect route is taken into use, or should a later stage in the indirect route be busy, further search is made over the direct route, and if unsuccessful the call is routed to a operator's position. The alternative route to one exchange may be the direct route to another. Transit group selector, Figs. 1-3, at tandem exchange.-This may be seized by a similar selector or by an incoming trunk selector and gives access to outgoing trunks, transit selectors in the same or other ranks and distributers leading to operator's positions. When an incoming trunk selector switches through, relay A pulls up, BA disconnects the testing-in circuit and K couples the common control circuit to the selector. In response to the digit, A steps the marking switch DA. As soon as the impulses determine that the wanted outlet is served by the even-numbered wipers, a circuit is completed over wiper DA8 for relay PP to pre-position the selector to the last contacts of the odd-numbered banks. At the end of the digit the dialling relay C disconnects CX and during the release period of CX tests are made over wipers DA4, DA5. If these are negative the selector searches the outlets of the wanted group and when successful relays H, HA switch through. Should all the outlets be busy the selector hunts for a free distributer, the distributers being connected to outlets near the end of the bank which are marked over wiper DA7. If again unsuccessful the selector stops at the last outlet from which busy tone is sent back. Delay working.-Trunk groups in delay are marked in the outlets of wiper DA5 by earth connected by a key at a supervisor's position. Thus, before CX releases, DL transfers the circuit of the test relay TA of the selector from the marking wipers DA6, DA7 to the marking lead of the distributer outlets and the call is routed to an operator's position. Alternative routing. If all outlets in the direct route are busy, delay working is not in force on the direct route and an outlet in an alternative route is free, earth is connected over a back contact of the all trunks busy relay in the storage equipment associated with alternative route and a front contact of the corresponding relay in the storage equipment associated with the direct route to the appropriate outlet of wiper DA4. Thus, before CX releases, RR connects TA to the normal contact of wiper 13 and breaks the circuit of PP so that the selector is held at or, if being pre-positioned, returns to its normal contacts. Relay AR, following RR, causes a coupling switch RH to hunt for a free register-translator. If all are busy a circuit is completed over wiper RH8 at one of two busy positions for relay DL which routes the call to an operator's position. Otherwise, test relay TH removes the shunt on CR which switches the wire - from relay A to relay AB in the register-translator, Figs. 4 to 7. The seizing earth over lead pr shorts a normally operated relay P but before this relay can release the shunt should be removed by the opertion of BB which follows AB, BC. BB operates a traffic recorder. The translator is prepared by the operation of relays D, CD, CV, DR, CN. Earth over relay CS which brings up CA is connected by straps to certain of the code wires WR ... R to operate a combination of relays AW ... AZ characterising the digit which selected the transit group selector. Relay DS pulls up in series with the code relays to operate the first relay NA of a counting chain NA ... NZ and DA which releases D, DS and switches the code wires WR ... ZR. CS releases and connects up CB so that the digit denoting the direct route is transferred by wipers DA2, DA3 to the second set of code relays BW ... BZ. CS is momentarily operated, CA releases and CC pulls up. In the translator, DS is followed by DB whereupon a translating switch MA moves to the outlet marked in MA12, MA14 by the two sets of code relays. Its test relay TD connects up a second translating switch MB which is stopped in alignment with MA by TF. TE follows releasing DS and operating D and S which energises DN. D connects high resistance battery over wire cr to operate relay TC, the marking switch MA returns to normal and RR, TA relapse. When PM eventually operates, the marking switch DA is set by the impulsing relay to which AX repeats pulses from a generating relay AA similar to that described in Specification 462,773. The pulses are counted by relays CF ... CJ, XA ... XC as described in Specification 654,852 and when the operated relays CF ... CJ correspond to the digit marked on MA1 ... 4 a stop relay SP pulls up (see Specification 471,987) followed by SZ which breaks the circuit for AX, AA and the counting relays and operates NB, SR. If the alternative route is connected to a selector in the preceding rank or in another group in the same rank, the first digit is eleven. In this case the digit ten is marked over MA1 ... 4 but due to the operation of CE over a wiper MA5 when TE operates, and the subsequent actuation of XE, the first impulse releases CE and the second is counted by CF ... CJ, XA ... XC as if it were the first. When a free outlet is found, the test relay TA removes a shunt on TB whereupon the translator loop is switched forward and TC, A, B, C release. The stop relay SP disconnects PM, the release period of which determines the inter-digital pause. PM releases SP, SZ followed by SR, NA. The translation consists of up to five digits of which up to three may be direct current and two voice frequency, these corresponding to NA ... NC; ND, NE respectively of the outgoing digit distributer NA ... NZ. The digits are marked by sets of four of wipers MA1 ... 4, MA5 ... 10, MB1 ... 11 connected in turn by NA ... NE. The number of digits is determined by earth connections over wipers MB12 ... 15 which are connected up by NA ... ND in turn. Such an earth connection results in the operation of DS which brings up the next relay in the distributer and releases the operated one. Relay ND prepares a circuit for VF which, when SZ next releases, connects the impulsing loop to a voice frequency source. TS may be strapped in circuit to lock up when ND operates to earth lead ZR, thus signalling the outgoing trunk terminal equipment to assume a transit signalling condition. The inter-digital pauses between certain digits may be increased by operated contacts of the appropriate distributer relays connected in the circuit of the condenser which controls the release period of PM. At the end of the last digit of the translation NF, NFA are operated and if TS is not strapped in circuit lead ZR is now earthed. Called exchange manual.-No incoming digits will have been stored in the translator so that relay DR is released when NFA operates. In positions associated with manual exchanges straps are connected to the outlets of wiper MA11 so that CO operates over a back contact of DR to connect low resistance battery to lead cr and to disconnect lead pr. In the selector control circuit TC connects up the switching relays H, HA, and relay TH falls back so initiating release of the translator and the control circuit. Called exchange automatic.-Further incoming digits are repeated by AB to a relay set RCRS comprising counting relays W ... Z, XW ... ZW (not shown) similar to the relays CF ... CJ, XA ... XC. At the end of each digit CD releases and connects earth over front contacts of W ... Z to operate combinations of storage relays such as SCX ... SCZ. CV, the slave of CD, falls back, whereupon CU locks up so that when CD is re-operated by the relapse of W ... Z the next relay of the incoming distributer DCA ... DCG is operated. Up to seven digits may be stored. The last relay DCG locks up over its right hand winding to prevent its release by an unintended impulse after the last digit. When all the translated digits have been sent, relays NF ... NZ connect up in turn the set of storage relays such as SCW ... SCZ and the stored digits are transmitted in the same manner as the translated digits. Relay DR is held by the operated incoming and outgoing distributer relays until the last digit has been sent, whereupon it breaks the circuit of CN which has a two-second delay. If a delayed digit should now arrive, relay W would hold CN. The release of CN brings up CO which signals the selector to switch through. Alternative route congested. If the last free outlet to the alternative route is taken, the selector drives to the last contacts where earth is temporarily connected over wiper 8 to the lead YR, which is also earthed directly from the congested selector or as the result of a backward VF signal if congestion is met with at a later stage. In the translator R operates, followed by RB which releases S, VF and the operated distributer relays NA ... NZ, opens the impulsing loop and brings up RS to disconnect wipers MA1 ... MA4. Relay D relapses. When earth is removed from lead YR, R, RB fall back, the former connecting positive battery to lead cr. At the end of the normal inter-digital pause SZ releases to operate