Patent GB-741204-A (GB)
Title: Telephone systems
IPC: H04M7/06
Filed: 1953-10-05
Abstract: 741,204. Automatic exchange systems. AUTOMATIC ELECTRIC LABORATORIES, Inc. Oct. 5, 1953 [Oct. 14, 1952], No. 27292/53. Class 40 (4). The sending operations of a register-translator or director are controlled by a common impulse machine which generates a constant stream of selective impulses at the standard rate and cycles of control impulses for effecting the connection of the selective impulses to an outgoing circuit. Further control impulses control a skip relay when less than the maximum number of digits are to be sent. The timing of the impulses is shown in Fig. 14A. The director described is intended for use in a system of the Siemens- Halske type in which the calling party is fed from the first selector and is assumed to be located at an office A of an area having a main office D, provision being made for routing calls directly in certain cases instead of through the main office. Registration of digits. When the director is seized from a finder-selector link, relay R1040 energizes over wire 308 followed by hold relay R1050, normally operated guard relay R910 being released. Tone relay R960 energizes over wire 309, connects line relay R940 to pulse-in wire 305, applies starting ground over wire 1447 to the common interrupter 1400 and operates the first sequence relay R410. Dial tone is sent to the calling party. If, however, the calling party has dialled prematurely, R960 fails to energize and dial tone is replaced by busy tone. The first dialled digit goes to vertical magnet M700 of the switch 800. If this digit is 5, denoting a call within the local area, post springs S705 operate and local area relay R710 pulls up when dialling relay R950 falls back and connects up release magnet M703. The selector drops back and R730 energizes in series with R410. The second digit thus sets vertical magnet M700, sequence relay R420 comes up in place of R410 and the third digit goes to rotary magnet M701. If the first digit is not 5, sequence relay R420 comes up at the end of the digit and rotary magnet M701 takes the second digit. Sequence relays R430 . . . R470 then direct the five numerical digits to relay registers 1301 ... 1305. In response to successive impulses, relays R1310 . . . 1350 energize first singly and then in combinations in the charging circuit of a condenser 944 which discharges between impulses. Unassigned codes. The relapse of R420 after the third local office digit or the second distant office digit energizes R510. The operation of R1020 by a PO pulse on wire 1424 connects R1010 to wiper 801 or 802. For unassigned codes, the corresponding bank terminals are strapped to terminal GPV and the next PV pulse on wire 1425 operates R1010, which disconnects R960 to revert busy tone. Zone metering. The next operation of R1020 by a PO pulse and its subsequent release connects up sequence relay R520 in place of R510. Ground on the PU wire 1441 then energizes R1140 which operates R1110 and connects pulse wire 1416 over wire 303 to step the metering switch 330. Stop relay R1160 is connected to wiper 801 or 802 the terminals of which are strapped to terminals X and thence to pulse wires SZ1 . . . SZIO according to the number of metering pulses required. Relay R1160 pulls up in due course, opens R1110 and connects inter-digit relay R1220 to wire 1168 to be operated by the SZ6 pulse in this cycle or the next. R1160 is restored by the next operation of R1020, and the next operation of R1140 restores R1220. R530 comes up in place of R520. If zone metering is not required, the terminals of wipers 801, 802 are jumpered to terminal GPU, so that the PU ground energizes skip relay R970 in series with R530 to prevent operation of pick-up relay R1140. At the end of the connection, metering is initiated by R320 and effected under the control of follow-up switch 340. Calls not routed through the main office. Up to three routing digits are needed if the called office is within the local area, but only one if it is outside. With R530 up instead of R520, pickup relay R1140 connects pulse wire 1416 to pulse out wire 306, and stop relay R1160 is connected to wiper 804 if local area relay R730 is up or to wiper 803 if that relay is back, so that the first routing digit is sent in according with the strapping to terminals X. Relay R540 comes up, and since main office relay R740 is back, sequence relays R550, R560, R570, R610 operate in succession in series with skip relay R970. On a local call, the second and third routing digits, if needed, are sent under the control of wipers 807, 806; otherwise circuits over these wipers and terminal G operate skip relay R970. On a non-local call, however, R710, R730 are back and R970 operates independently of the switch 800. The five numerical digits follow. Calls routed through the main office. Three routing digits are followed by the two or three office digits as registered. In this case the relevant wiper 803 or 804 stands on a terminal connected to terminal GPV. With R530 up, a PV pulse on wire 1425 energizes cycle relay R720 whereupon main office relay R740 operates in series with R540 and skip relay R970 and connects stop relay R1160 to terminal YA to determine the first routing digit, which is sent as described above. The second and third routing digits are determined similarly by connections to terminals YB, YC. When the call is a local one, the first office digit is determined by a strapping from terminal YD and terminal XS, the first digit 5 having been absorbed, and the subsequent office digits are controlled over wipers 808, 805. When the call is non-local, however, R730 is back and a skip circuit exists for sequence relay R610, and the two office digits are controlled over wipers 808, 805. Alternative routing. This is provided on local calls not normally routed through the main office by straps between vertical bank V and terminal G. Since R730 is up, sequence relay R420 connects re-route relay R1230 to vertical wiper 809, and the latter operates if an alternate route is provided, followed by R1240. If an all-trunks-busy condition occurs, ground on wire 304 when R640 is up energizes R1210 which locks provided R1240 is up and operates main office relay R740. Ground is removed from wire 309 to release the selector 212 and sequence relay R540 reoperates, so that the director now re-routes the call via the main office. On non-local calls not normally routed through the main office, R730 is back and operation of R1230, R1240 follows that of interdigit relay R1220 during the zone metering control. In this case ground on wire 304 energizes R1210 when R650 is up. Release of director. Each operation of cycle relay R720 is followed by that of R1150 and R1120 energizes to ground on pulse-out wire 306. When the connection is complete, however, R1120 fails to energize and allows the operation of release relay R1130. Should the calling subscriber fail to dial, the non-operation of dialling relay R950 effects release of the connection after a timed interval. Toll calls. The single digit 1 is registered and post springs S704 are operated. With line relay R940 up, one-digit code relay R920 energizes in the charging circuit of condenser 944 and puts R940 under the control of cycle relay R720 to send a single impulse to rotary magnet M701. Sequence relay R430 operates in place of R420, connecting up send sequence relay R510 and releasing R920. No zone metering digits are required, and digits are sent back to route the call to a toll switchboard at the main office. R630 prepares circuits over springs S704 for release relay R1130 and also for re-route relay R1210 if desired. Special service calls. Two digits 31 are registered and post springs S704 are operated. Two-digit code relay R930 follows R920 during the first digit and the second digit goes to rotary magnet M701. A single digit is sent to route the call to the appropriate switchboard. Registering and sending of additional digits, e.g. on calls to a PBX or party-line. The fifth numerical digit goes to register 1305 while sequence relay R470 is up. Dialling relay R950 connects up R480, which holds if the first numerical register is occupied, and, at the end of the digit, R430 comes up again. If at this stage a further digit arrives, R950 operates unassigned code relay R1010 to return busy tone. But if R480 does not hold, the further digit sets the first numerical register, and subsequent digits may be received in the same way. After the fifth numerical digit has been sent with R670 up, interdigit relay R1220 operates R1250 (lower) which connects fresh dialling tone to R940 and is released differentially when R950 next comes up. R1170 follows R1250 and prepares a fresh circuit for R630 for the sending of the additional digits.