Patent GB-392317-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/58
Filed: 1932-03-04
Abstract: 392,317. Exchange systems. ELLIS, H. 0., 13, Atkins Road, Clapham Park, London, and WINCH, B., 41, Woodland Gardens, Isleworth, Middlesex. March 4, 1932, Nos. 6527 and 18828. [Class 40 (iv).] Groups of subscribers are associated with a single line to a manual or automatic exchange at a switching station comprising a number of selecting relays and obtaining its operating current from the exchange. Selection is effected in the system described by means of currents of different strength and in some cases different polarity over the talking line or over a separate auxiliary line, direct current receiving relays associated if necessary with rectifiers being employed. Reference is made to the use of polarized receiving relays. The systems described provide for reverting calls which are non-secret. Reference is made to systems in which only outgoing and incoming calls are possible and in which tone currents are supplied to the lines not engaged in a call. In the automatic system a relay combination is provided at the exchange for selecting the meter of the calling party and a discriminating switch controls the release of the exchange switches in reverting calls. According to the first Provisional Specification, mechanically latched relays may be used at the switching station or selection may be effected in accordance with the frequency of alternating currents. 4-Line station on manual exchange with control wholly over speech line, Fig. 1. When any subscriber calls, the common line relay L at the exchange lights a calling lamp. The operator plugs into the answering jack AJ energizing CO to extinguish the lamp and GA .. GD to busy the line at the calling jacks. On learning the calling and wanted numbers she removes the plug, releasing CO, GA.. GD and inserts it in the jack of the calling subscriber, the sleeve relay KA .. KD of which disconnects the corresponding relay GA .. GD and energizes the other three. The sleeve relay energizes CB which is followed by CA which locks, CD and CC which locks itself and cuts off CB, which falls sluggishly followed by CD. As a result the lower line wire is first connected to + or - strong or weak battery and then to ground over F. At the switching station, the selecting relay or combination, A, A and B, C or C and D is energized in series with X. The selected combination locks up over the upper line wire in series with XX, the operation of which is delayed by a short-circuit until X has been released by the termination of the selecting impulse. XX completes the talking circuit at the switching station. F pulls up on the relapse of CB, locks and makes a clean talking path at the exchange. A retard ZZ or retard and condenser may be connected to the lower line to balance the selecting combination on the upper line. On an incoming call the selecting combination is controlled in the same way, L is energized in the holding circuit and energizes F. A reverting call is completed by plugging into IT before plugging into the wanted jack. P energizes S to prevent the operation of F by the relapse of CB. Ringing current from the cord energizes RR which connects up a ringing source RG. When the key is restored RR falls and the reply of the called party energizes F which locks up and releases the selective combination and relay S which completes the circuit to the feed in the cord which the operator now plugs into AJ, removing the other plugs. 10-Line station on manual office with control over auxiliary line. In a modification, Fig. 2 (not shown), the individual sleeve relays connect + or - strong or weak battery to two auxiliary wires, each of which is grounded at the switching station through oppositely directed rectifiers in series respectively with a single relay and with a pair of relays of different sensitivity. In this case the subscriber receives a tone signal until the operator answers. The relays CA.. CD, F and S and the special reverting call jack are omitted. 8-Line system on automatic office, Fig. 3. (1) Outgoing and reverting calls. The individual line relay LA.. LH at the switching station pulls up in series with the line relay AC at the exchange which is followed by BC, AG, BG and GA.. GH which busy the various appearances of the line in the final selectors. BG connects battery over relays P .. S to the auxiliary wires CL1, CL2 which are grounded at switching station through selecting relays A .. D, resistances and holding windings and contacts of the line relays. As a result a combination of P .. S and a corresponding combination of A .. D representative of the calling party are energized and he is given exclusive use of the line. The P .. S combination locks up in series with GX which loops the outgoing line to start the line switch. AC repeats the digits to the selecting switches and to magnet CS of the switch CS1, CS2, CS3. If the call is not a reverting one, the relapse of the parallel relay CC after one of the first three digits energizes TC which locks, cuts off AC putting the selectors under direct control of the dial and holds the selective combination after the relapse of BC, BG. In a reverting call, however, TC remains unoperated and at the end of the 3rd digit WN arranges for the operation of K at the end of the 4th. K releases the selector switches and relay AG and over CS2 energizes the relay KA .. KH of the wanted party which releases the corresponding relay GA .. GH, energizes X and connects strong or weak battery to the auxiliary lines to operate the appropriate selecting combination A... D at the switching station. BG falls on the relapse of AG and energizes LN which rings the line. When the subscriber replies, F releases LN and reoperates AG to release the switching station relays. Talking feed is derived from AC. (2) Incoming call. Relay KA .. KH is operated in accordance with the route over which the line is seized, energizes X which energizes IC and also all the relays GA .. GH except the one corresponding to the wanted subscriber and operates the selective combination at the switching station. IC cuts off AC and the line is rung in the usual way from the final selector. Non-reply in reverting calls. After the operation of LN, earth pulses on 60, 61 operate TP, Z in succession. If F has not operated by this time, Z energizes AG, releases LN, locks up and connects up busy tone at 62. Metering. Meters are connected to the individual sleeves in the manual systems. In the automatic system the required meter is selected by the P .. S combination and operated over a 4th wire ME.