Patent GB-334524-A (GB)
Title: Improvements relating to automatic telephone systems
IPC: H04Q3/00
Filed: 1929-05-31
Abstract: 334,524. Siemens Bros. &. Co., Ltd., and Christian, D. A. May 31, 1929. Automatic exchange; metering and party-line systems. - A calling line, with the aid of an assigner as described in Specification 332,904, takes into use an " operator circuit which selects an idle connecting circuit, sends the tens digit of the line to the two-motion finder of such circuit and subsequently responds to impulses at the same time as the connecting circuit and controls it in the establishment of various kinds. of call. The system described comprises satellites having sub-satellites and called " parent offices." In the case of calls from a subsatellite, an operator circuit is taken into use at the parent office as well as at the originating office but drops out again if the call is for the main office or for another satellite. The connecting circuit. at a satellite may comprise separate switches for local and outgoing calls. Discrimination is effected by the operator circuit at the criginating office which also controls metering, that at the terminating office controlling the selection of a line to a P.B.X., the testing and ringing of ordinary lines and the generation and selection of code ringing currents for party lines &c. In the case of reverting calls, the operator circuit causes the line to mark itself busy and releases the connecting circuit. Inward calls are set up over junctions terminating in selectors. One junction is kept associated with an operator circuit and only that junction is selectable at the outgoing office. When all the others are busy, this operator circuit may be taken by a local subscriber and the incoming selector may, with the aid of the. operator circuit, be used for trunk offering. Extension of calling line to main office. The combined line and cut-off relay L on operation over its winding (i) operates only its contacts l1. l2 to start an assigner, not shown, in search of an operator circuit and mark the line to the finders of the connecting circuits. In the selected operator circuit, S connects up the test relay T and GMA interacts with magnet DFA until the wipers A1 - - A7 are on an idle connecting circuit whereupon T pulls up in series with TT, Fig. 2, which energizes JT, and GMB interacts with DFB to drive the wipers Bl - - B7 to the same connecting circuit. GMB is then shunted out over A1. TA, GD (over GD (i), Q pull up and X, Y interact to provide stepping impulses for the switches. Magnet LS drives wipers LS1 LS3 and impulses are sent out synchronously over GD (ii) to the vertical magnet VM of the finder CF. LS is stepped on the position corresponding to the tens digit of the calling number by M which also disconnects VM and completes an impulsing circuit for the rotary magnet RM. When the calling line is reached this circuit is opened by TC which pulls up in series with the cut-off winding (ii) of L, and extends the loop to retard RC and impulse relay A which energizes V, and SS is driven off normal with the help of DS. D then pulls up (over D (i) in series with DS which does not operate) to release the assigner and SM fall back. On the relapse of GD which was cut off by V, vertical magnet VM1 of the selector CS receives an impulse which is terminated by the relapse of Q shortly afterwards. DR then makes a new circuit for X and Y and impusing circuits for the rotary magnet R1 and the switch DSA. When an idle junction is reached P is energized over P (i) in series with PP, locks over P (ii), short circuits P (i) energizing PP and energizes PT which locks and sends DSA home, and connects battery to the b wire to initiate the selection of operator and connecting circuits at the tandem office (if any) or to seize the selector at the main office. DR holds during hunting over multipled terminals of DSA corresponding to the junctions, except the last, in the selector. On the relapse of DR when P pulls up or when the last junction is reached, G falls. Discrimination. Dialling tone is sent back from the main office and relays A at the originating office and tandem office (if any) repeat the impulses over the junction b-wires and via D (ii) to DSA. The first impulse energizes DS to cause SS to move to its 2nd terminals. At the end of the 1st digit D falls and SS moves to its 3rd terminals and D pulls up again over D (i). If the call is to terminate in the parent office or one of its sub-satellites, DSA5 at the parent office will now be on a terminal jumpered to P (ii) and when SS moves to position 3, P(ii) is short-circuited and releases PT which short circuits JT by ground from SS10 via. the vertical wiper and sends DSA home. On the relapse of JT, release magnet ZM1 is operated. The hundreds digit is repeated to DSA and VM1, the 1st impulse causing SS to step on as before, and at the end of the digit SS advances to its 5th terminals. If the call is to terminate in the parent, release magnet ZM, is operated again but if it is for one of the sub-satellites, JT is operated and when SS goes to 5, CO is operated over DSA3, locks and grounds DSA4 whereupon DR operates and switch DSA and relays G, P, PP control the selection of an idle sub-satellite junction as described above in connection with the selection of a main office junction after which DR falls and PT pulls up and locks itself. If the call is for the main office PT is not released in position 3 and if the call originated in the parent the operator circuit is held to control the selector as described below, but if it originated in a subsatellite, JC was operated when the call finder stopped and in position 5 a circuit is made for relays VY, VA, the incoming junction is switched through to the outgoing junction, and the operator circuit leaves the call and is restored to normal, subsequent digits being repeated by AA. If the call is local to a sub-satellite, CO is operated in the sub-satellite operator circuit after the hundreds digit, and short circuits P over DSA4. P<T> falls back shunting out JT and operating ZMl and the apparatus ahead is thus released, the connector being controlled by the remaining digits as described below. Completing call to ordinary line. DSA is stepped by the tens digit SS moving to 6 at the beginning and 7 at the end of the digit so that the units digit goes to DSB. These digits also operate VM1, RM1 at the terminating office. G is energized when SS goes to 8 at the beginning of the digit and is released when it goes to 9 at the end. A momentary test circuit is thus made over P (i), PP. Ii the line is busy, the relapse of G connects up busy tone on BS. If it is idle P locks over P (ii) and energizes PP, PA pulls up, and ringing current goes forward from RG over TR (i) and ringing tone goes back from RS. When the called party replies, TR locks over TR (ii) and energizes VY, VA to complete the talking circuit and connect up supervisory relays AA, YY. If the call originated in a sub-satellite, JA is operated and YV repeats the reply signal over the a-wire to operate TR in the originating office. Completion of call to party-line. If the call is for a party-line, DSB energizes R which locks and connects up the code-selecting switch RC which responds to an extra digit for selecting, a ringing code. SS moves to 10 at the beginning and to 11 at the end of this digit. Circuits are now made for relays X, Y, Z which interact to cause Y to deliver impulses to the code switch RD. RR operates in accordance with the code and connects ringing current on RG1 to the line. When the code has been sent RT is energized to provide a circuit for the ring trip relay TR. A code ring back tone is sent back from CRS. When the called party replies the operator circuit is released as before and on the relapse of V, R falls stopping the interrupter set and causing RC, RD to go home in succession. Reverting calls. The subscriber dials a special two digit number and then rings the line with a magneto. The 1st digit is the local call digit and the 2nd operates DSA to a position in which a circuit is made for RL which connects weak battery to the 4th wire to operate a special relay (not shown) provided on party lines. This relay locks up while there is an instrument off its hook at one of the stations holds L fully operated and busies the line. RL also releases V and the operator circuit and connector circuit are restored. Metering and release of operator circuit. MR pulls up when both supervisory relays are energized, locks up, connects metering battery over A2 to the 4th wire, and releases V whereupon T, TA, TR, P, PA in the operator circuit and TT, TC in the connector fall back and release A in the operator circuit. Homing circuits are made for DSA, DSB in succession and for SS, LS in succession and finally MR falls. Release of connection. When the calling party hangs up AA releases VA which operates the call finder release magnet ZM. When the called party clears YY releases VY and ZM1 is operated to release the connector. If either party fails to clear an alarm is given over PL. Completing call to PBX. Contacts in banks DSB2- - DSB8 corresponding to lines, other than last lines, of PBX groups are connected to DR so that if the 1st line is busy and P therefore fails to operate when SS moves to 9, the interrupter set is started and sends impulses to the rotary magnet via A7 or E16. The control is the same as in hunting for a junction. Inward calls. When an operator circuit is idle, battery is connected to its wire 22 via TD, and when it is busy this wire is disconnected or includes a resistance. In the latter case, provided common relay GP (not shown) is back, GM interacts with DM to drive the switch until it is shunted by the low resistance of TD. TB then pulls up, disconnects GM and marks the operator circuit busy operating TD. TB connects RC to GP which prevents other switches ICS from hunting. Battery over RC, Fig. 3, is row connected over the junction to TS which marks the junction selectable by connecting TN