Patent GB-258741-A (GB)
Title: Improvements in telephone systems
IPC: H04Q3/00
Filed: 1925-03-25
Abstract: 258,741. Standard Telephones & Cables, Ltd., (formerly Western Electric Co., Ltd.), (Deakin, G., and Polinkowsky, L.). March 25, 1925. Automatic exchange and metering systems.- Repeated metering of calls in either direction over a two-wire trunk is controlled by apparatus associated with the trunk. Preferably a timing device at one end controls the metering of all calls. The timing device may be made to release a connection after (say) six minutes, the trunk being made free for other calls and the subscribers' lines, if they do not hang up, being disabled as described in Specification 258,775. Separate meters for local and trunk calls may be provided. Specification 197,797 is referred to in the Provisional Specification. The invention is described with reference to a rural office of the kind described in Specification 258,775, in which local calls are completed by means of connecting circuits, Fig. 1, comprising a call finder and a connector. Tie line calls, i.e. calls over direct trunks to another rural exchange, are set up by setting a local connector to a particular position, whereupon call finders FS1, FS2, Fig. 2. connected to tie lines to the wanted office, hunt for the calling line, and the local connecting circuit is released. At the distant office, local connecting circuits hunt for the calling line and the successful one is operated by further digits repeated over the tie-line. The circuit arrangement for setting up a tie line connection are the same as those described in connection with Fig. 3 of Specification 258,775, but additional relays and a timing arrangement are provided for controlling release and metering. Repeated metering-timing switch at outgoing end. When the called subscriber replies, the metering relay, as in the case of local calls, connects booster battery to the c-terminal of the finder. Relay Yr1 repeats the booster impulse over the bridge Ar, Xr, Zr, and the marginal relay Zr energizes relay Nr which locks up, takes release control from relay Br, energizes relay Rr and moves the timing switch TSM one step off-normal. Relay Rr puts a ground on one end of a common relay Jr, the other end of which receives battery impulses from a clock every six seconds. Relay Jr repeats these impulses to the timing switch magnet TSM, which thus moves the switch one step every six seconds. When however the wiper g1 encounters a terminal connected to the sluggish relay Qr the switch takes a step automatically, relay Qr operating as a stepping relay. Just before the end of the first three minutes, wiper e1 reaches position 34 in which ringing equipment is started over SRC and a tone signal is sent back therefrom over TRC and the switch moves automatically to position 37. If in response to the release of the connection relays Ir, Ar, Xr, Rr fall back by the time the switch reaches posi. tion 36, circuits are made for stepping the switch quickly out of position 37 and then less quickly under control of relay Qr from position 38 to normal. In positions 38, 40, 42, wiper e<1> energizes relay Pr which connects booster battery to the c-wire to operate meter MS which cuts in an opposing winding to make itself quick-to-release. Relay Cor, Fig. 1, falls back momentarily during the change-over of relay Pr and increases the time the meter circuit is broken. A relay Or in the booster circuit disables the local finders while the metering potential is on the c-terminal. In position 44 relay Nr is shortcircuited and release is completed by the relapse of relays Br, Cor, Cor1, Dr1. If, however, the three-minutes warning is ignored, relay Hr becomes energized in position 37, locks up, disconnects the metering terminals 38, 40, 42, and the releasing terminal 44 in the e bank and the last 7 terminals in the g bank, and prepares a further set of metering terminals 26, 32, 35. The six minutes warning is given in position 24 and metering tabes place in positions 26, 32, 35. If the call is released relay Hr which is short-circuited in position 36 is not re-energized in position 37 and metering and release take place in positions 38, 40, 42, 44. If the subscriber's call takes more than six minutes metering takes place every three minutes until the subscribers hang up, in positions 26, 32, 35, and after release a further three operations takes place in positions 38, 40, 42. Repeated metering-timing switch at incoming end. Relay Yr repeats the booster impulse to relays Sr, Rr. Relay Sr locks up, energizes relay Nr, and allows relay Ur to pull up over the tie line and lock up relay Rr. No metering can take place during the first six minutes of conversation, but when the calling party hangs up relay Lr1 removes a shunt from the high resitance bridge Vr1 Zr1 Relay Vr1 pulls up and holds relay Br1, but relay Ur falls back and releases relay Rr, and the local line relay releases the local connecting circuit. Relay Vr1 remains held by ground and battery supplied over back contacts of relay Rr. The timing switch is restored to normal and operates relay Pr three or six times as described above. Relay Pr replaces ground on the a-wire by booster battery to operate the marginal relay Zr1 which repeats the impulses to the subscriber's meter. When relay Nr is short-circuited, relays Pr, Sr and the operated relays at the outgoing end are released. In case the call takes more than six minutes, metering impulses are sent every three minutes to the left-hand winding of relay Zr1 relay Ur being released by relay Pr at each impulse and releasing relay Rr. Forced release after six minutes-timing switch at outgoing end. To provide for this, the connectors are altered as indicated by the dotted apparatus and crosses. As a result, the first operation of relay Pr unlocks relays Br, Rr, and when relay Nr is short-circuited, release is completed by the relapse of relays Cor, Dr. If the subscribers do not hang up their lines are disabled as described in Specification 258,775. Forced release-timing switch at incoming end. Metering takes place as previously described, and after the sixth impulse, relay Wr reverses the current flow in the tie line. The two windings of relay Xr1 then oppose one another and relays Fr1, Br1 fall back to complete the release at the outgoing end. The relapse of relay Nr completes release at the other end. Separate meters. Instead of controlling the same meter as is used for local calls, relay Pr may deliver impulses to a separate meter connected to the d-terminal in the call finders.