Patent GB-692999-A (GB)
Title: Telephone systems
IPC: H04M15/04
Filed: 1950-02-01
Abstract: 692,999. Automatic exchange systems. AUTOMATIC ELECTRIC LABORATORIES, Inc. Feb. 1, 1950 [Feb. 12, 1949], No. 2630/50. Class 40 (iv). An automatic exchange comprises a plurality of register senders each including a plurality of digit registers and a control switch, the exchange also comprising a translator with a plurality of translating devices each individual to a called exchange and means for associating one of the register senders and its control switch with the translator. Figs. 4-31 are arranged to form one circuit as shown in Fig. 32. Selection of idle primary selector and idle director. Closing the loop at substation 401 employs distributer 442, rotary distributer 441, and idle line finder 440 in known manner to connect the subscriber's line conductors 402, 403 to conductors C444, C445 of the associated primary selector 500, line relay R530 operating to energize hold relay R540, which maintains the line finder 440 and cut-off relay R410 and at contacts 546 initiates operation of director hunter, 450, rotary magnet M451 operating intermittently to advance the wipers 453-460 until absence of ground on the contact associated with wiper 460 indicates an idle director, when director test relay R510 operates, its high resistance preventing operation of M451. Relays R530, R540, R550 then relapse. Operation of director hunter and primary selector if all associated directors are busy. If a director is available, relay R601 grounds contacts 23, 24, 25 to enable wiper 460 to advance, if necessary, into engagement with contact 1 again. When a director is in use, its busy relay R610 grounds conductor C475 and energizes director busy relay R606, When all associated directors are busy, relay R601 releases to remove ground from conductors C465-C467, whereby the wipers can stop on contacts 23-25. If, now, the wipers engage contacts 23, they seize hold and busy tone circuit 582 and director test relay R510 operates to halt the wipers and mark contact 23 busy. Relays R580, R585, R590 energize to actuate a busy meter (not shown) and transmit busy tone over conductor C595 to the calling subscriber. If other calls are made while the first hold and busy tone circuit is in use, the director hunter advances its wipers to position 24 or 25 to operate a second or third hold and busy tone circuit 583 or 584. Circuit 582, 583 or 584 is released when the related subscriber hangs up. Seizure of an idle director. When the director hunter 450 seizes an idle director, wipers 456, 457 extend the calling loop over conductors C470, C471 to the code switch 1100 over both windings of party line relay R 1130 and the upper winding of line relay R1140, the latter pulling up but R1130, being differentially wound, not operating. R1140 operates hold relay R1150 which energizes seizure relay R750 in the controller 600 and connects impulse conductor C1135 to wiper 1192 to apply twelve impulses per minute to timer 1190. Seizure relay R750 (1) applies ground to conductors extending to coder 1800, call register 1500 and call recorder 2000, (2) locks director test relay R510 and operates hold relay R820, (3) operates director busy relay R610 and biases delay send relay R910, (4) starts pulse generator 700, which applies pulses to pulse relay R880 at a rate of ten pulses a second. Class test. Hold relay R820 energizes class test relay R720. If ground from terminal 425 is jumpered to terminal 428 in the line circuit 405, relay R670 energizes to show that the calling line requires class 2 service. R720 also energizes control relay R730 slowly to restore R720. If resistance battery from terminal 426 is jumpered to terminal 428, relay R710 pulls up to show that the calling line requires class 3 service. If neither R670 nor R710 energizes, the line requires class 1 service. Restoration of R720 restores R730 slowly and operates R760 to light the appropriate class indication lamp 676-678 and extend dial tone to the calling line. Dialling called number. (1) First digit. The subscriber dials the first two letters of the called exchange and the numerical digit characterizing the exchange within a zone, i.e. the ABC digits, followed by four numerical digits. For zones comprising a single exchange, the C digit is omitted. Line relay R1140 in the code switch 1100 follows the pulses, the first pulse operating slow-release digit relay R1160 which remains up while R1140 is pulsing. R1160 energizes sequence control relay R830 which operates magnet RM1511. Line relay R1140 also applies pulses over conductors C1138, C717, wiper 1514 and contact 1 to rotary magnet RM1521 of the first code register 1520, the wipers 1523-1527 of which are advanced to register the first digit. Restoration of digit relay R1160 at the end of the first digit releases sequence control relay R830 to light station dial lamp 823 and operate R620 to cut out dialling tone. R830 also restores rotary magnet RM1511 to advance its wipers one step whereby the impulsing circuit is transferred to the second code register 1530. (2) Party line test. During dialling of first digit, R1150, R1160 are operated to energize control relay R1180 which shunts party test relay R1170. At the end of the digit train R1160 restores so that R1170 pulls up in series with R1180, to make new connections of battery and earth to the calling line. The second, third and fourth parties on a party line have special dials of the type described in Specification 565,654, which emit one, two or three ground impulses after the usual train of impulses. With contacts 1172, 1174 thrown, the ground impulses through the windings of party line relay R1130 act in the same sense and R1130 responds to ground conductor C1199 one, two or three times for a purpose described later. (3) Dialling remaining digits. Line relay R1140 repeats the pulses of the second digit to the register and R1160 operates control relay R1110 because R1170 is still energized. At the end of the digit, restoration of R1160 removes the shunt from disconnect party test relay R1120 which operates in series with R1110 to release R1170, R1180 to restore the previous loop circuit to R1140. The remaining digits are received and repeated by R1140 in the same manner as for the first digit. Registration of called number. As already described, rotary magnet RM1521 advances its wipers according to the impulses in the first digit, and wiper 1527 marks one of wipers 1201-1208 in code switch 1100, after which R1160 restores to restore R830 and RM1511, which advances the sequence switch one step, wiper 1514 transferring the impulsing circuit to the second code register 1530 which registers the second digit, RM1531 repeating the train to vertical magnet VM1210 which lifts wipers 1201-1208 a corresponding number of steps. In a similar manner, the third digit is registered on the wipers of register 1540 and through rotary magnet RM1211 rotates the wipers 1201-1208 a corresponding number of steps. The first three digits thus complete a marking circuit over a particular contact in the code switch 1100 to call for a translation from the common translator, as described later, if such is necessary. The last four digits, in the case of local calls, control the local switch train directly from the subscriber's dial, but in other cases, they are set up in the numerical registers 1610, 1620, 1630, 1640 in a manner similar to that already described. Party line registration. While wiper 1516 is in position 1, conductor C1199, which is grounded by party line relay 1, 2 or 3 times, is extended over conductor C1517 to control relays R2010-R2060 to register the identity of the calling station on a party line, as described later. Local calls. Terminals in terminal block TB1528 corresponding to the code digits of the exchange are jumpered to terminals 1561, 1562, 1563 so that when the first two digits of the local exchange have been dialled, ground is extended from wiper 1526 through terminal 1562, wiper 1536, terminal 1561 and conductor C888 to operate local relay R840, which energizes line relay R530, hold relay R540 and transfer relay R550 in the primary selector. If, now, the third digit of the local code is dialled, wiper 1546 applies ground over terminal 1563 to energize third digit local relay R850, while line relay R1140 repeats the third digit over contacts 1142 to line relay R530, which repeats the digit to the vertical magnet VM575 of the primary selector. Restoration of R1160 and R830 at the end of the digit operates director release relay R780 in series with R850 and operates a peg count meter to count the number of local calls. R850 restores transfer relay R550 to operate rotary magnet RM576 which releases and energizes in turn with rotary relay R560 to advance wipers 563-565 stepby-step until an idle trunk, indicated by absence of ground on wiper 565, does not re-operate R560 but causes switch-through relay R520 to pull up, disconnecting line relay R530 from the calling line which, assuming that director test relay R510 has released, is connected to the succeeding switch. Release of director on a local call. As already described, operation of director release relay R780 restores director test relay R510. R510 disconnects the director and reconnects conductors C444-C446, whereby the remaining digits are transmitted directly from the subscriber's dial to the switches in the local switch train in known manner. Disconnection of the director restores R1140, R1150, R750 and any operated relays in the code switch 1100. Release of R750 completes a circuit from ground at the home position of wiper 1667 in the sender switch 1600, through wiper 1643 of the fourth numerical register, interrupting contacts 1642, rotary magnet RM1641 and director release relay R780 to battery, to step the wipers of the fourth numerical register 1640 to home position. Ground is then fed to the third numerical register and so on so that all the registers of Figs. 15 and 16 and sequence switch 1510 are restor