Patent GB-772013-A (GB)
Title: Improvements in or relating to automatic telephone systems
Inventor: READ DOUGLAS AUSTIN
IPC: H04Q3/42
Filed: 1954-04-24
Abstract: 772,013. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. April 5, 1955 [April 24, 1954], No. 11898/54. Class 40 (4). In an arrangement using motor uniselectors, common high speed hunting equipment selects an outlet and gives a gas tube therein, thereby marking the outlet for selection by the uniselector. The common equipment may then be released before the hunting operation of the uniselector is complete. The invention is described in relation to the selection of outgoing junctions J by uniselectors LRS whose outlets .are connected via a grading to the junctions. When the outgoing switch LRS is seized, line and hold relays A and B operate, the former earthing the start lead ST for the registerconnector RC. Connection to a register is then established over leads A2, B2, SW, LM and IMP, and the register is also connected to lead OT of the junction selector control unit FCU. The second and subsequent digits are repeated by A to the register over lead IMP. When digits indicating the required exchange have been received a hunting switch associates a translator with the register, provided the junction selector control unit FCU is marked free over lead OT. The translator TR then applies H.T. to leads HT (Fig. 2) and THT (Fig. 3) associated with all outgoing lines. The register earths LM to bring up relay ST, and STA, STB follow to associate the switch LRS with the junction selector control unit FCU. Relay UB follows to busy the control unit by disconnecting lead OT, and applies H.T. to tubes VK1, VK2 and priming potential to tubes VK1, VK3. Meantime the exchange code is transferred from the register to the translator. A pulse is then applied via lead PR to all tubes VK3 associated with outlets in the wanted direction. Firing thus takes place of those VK3 tubes which have been primed, i.e. those whose associated outlets can be reached over switches such as LRS which are controlled by the unit FCU. The corresponding VK5 tubes are thus primed over lead MK and the tube VK4 is fired if the outlet is free (DP unoperated). The cathode resistor of VK4 is contained in the translator TR and the potential across it provides a marking for high-speed hunting equipment, and when this marking is found a pulse is applied to the corresponding lead HSHS to fire tube VK5. VK5 fires VK6 which brings up relay DP, thereby causing VK7 to fire after a short delay. Relay DP busies the junction against selection by the translator. VK6 also applies bias to mark that one of a plurality of multi-metering units MMCU to which the translator must pass its metering information. The firing of VK5 also provides a pulse over lead SZ to all tubes VK1 in the various switch multiples having the circuit OJRS as an outlet. The primed VK1 tube strikes and potential over its cathode resistor provides a marking for the switch LRS. The translator also pulses lead SH to fire VK2 and relay SH follows to energize the latch magnet LM of the switch LRS which hunts, testing four outlets at a time over banks T1 ... T4 until the marked outlet is found, whereupon one of the test relays TA ... TD operates to stop the switch. Relay H is thereupon operated in combination with neither, either or both of the wiper switching relays WSA, WSB according as TA ... TD is operated. Relays H, STA, STB, UB, TA, TD and SH then release and VK1, VK2 are extinguished. The register wires A2, B2 are now connected to the -, + wires of the outgoing junction J and the remainder of the digits necessary to complete the call are transmitted to the next exchange. When this has been effected the register brings up relay SW in the switch to release A, and also to put +ve battery on the P-wire to bring up BB in the outgoing relay set OJRS. Relay SW also removes holding potential over lead H to release the register connector. Relay BB is followed by MF and BA which inserts the usual feed bridge in the talking circuit, line relay AA operating therein. When the called subscriber replies reverse battery is received over the junction, so that relay D comes up, releases MF, and connects a starting earth to lead ST of the multi-metering control unit MMCU, which at appropriate intervals operates J the requisite number of times. Warning tone is injected via the middle winding of AA on all metering operations except the first. Relay J reverts the usual booster battery on the P-wire. If the call is to a manual board reverse battery is not received but battery over the + wire operates MF via relay I. If all outlets are busy the translator stops after testing the last outlet and signals the register which thereupon operates SW so reverting busy tone via the middle winding of relay A, relay H not being operated in this case.