Patent GB-452425-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04M7/06
Filed: 1935-02-18
Abstract: 452,425. Automatic exchange systems. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, and BEALE, C. E., 59, Towers Road, Wavertree, both in Liverpool, and KENNEDY, T. A., 5, Caroline Place, Birkenhead. Feb. 18, 1935, No. 5243. [Class 40 (iv)] In a system involving satellites and subsatellites, the number of impulse-repetitions, occurring in a connection from, say, one subsatellite through the main exchange to another sub-satellite, is reduced by arranging that at successive stages of the extension of the connection the normal feed is automatically cut out in response to digits indicating a through call, and a bridge including a neon lamp in series with a relay is connected up to control release. Figs. 3-6 show a discriminator at a satellite used in extending calls from a sub-satellite, the junction between the satellite and sub-satellite being also used for calls in the reverse direction in which case it is seized either by a local discriminator or by an incoming selector terminating a junction from the main exchange. Operation of discriminator; out-going call to main exchange. When the discriminator is seized from the sub-satellite, relays A, B, BX operate and a single-motion switch (right-hand wipers - , + , Fig. 4, and H, P, Fig. 6) hunts for a junction to the main exchange. Relay K then operates in series with the driving-magnet JHM and grounds wiper P to operate junctionguard relays JA, JB. If all junctions are busy the switch moves to the end of its bank at which K operates. In either case, dialling- tone DT is transmitted. The first digit is repeated by relay A over the junction and to the vertical magnet VM, relay JG operating during the digit and releasing the normallyoperated relay ML. If the digit denotes a connection via the main exchange (1 to 6 or 8), relay SW operates over vertical bank VB and terminal J or X, energizing SR which completes a metallic circuit to the junction, with a bridge through neon-lamp NL and relay RX. Relay SW short-circuits ML, locks over its back contact ml1, and on the release of A holds B operated. Similar neon-lamp bridges are connected up at the main exchange and any further satellite and at the end of conversation, a high voltage is connected to the negative line at the terminating exchange causing the neon lamps to strike. At the discriminator, relay RX operates, releasing SW, B and causing the completion of a circuit for the release magnet ZM. Call completed locally. On receipt of the first digit (7), the release magnet ZM operates over terminal LA and bank VB, and when release is complete, relay AD operates energizing LD which releases BX and the junction. The second digit (1) is similarly absorbed, relay LC operating over terminal LB. Relay LX then operates, disconnecting the vertical bank VB, and the switch is set by the third digit and hunts for a free local final-selector. If the third digit represents a non-selectable level, post-springs NP1 close a circuit for relay OF to connect up NU-tone. Similarly, if the second digit is incorrect, relay OF operates over terminal X and bank VB. Long-distance call. Relay LD operates over terminal T releasing BX and the junction, and operating relay AR which connects up the rotary magnet RM to cause the selector to hunt over its normal level for a special high-quality junction to the trunk exchange. Relays H, SW, SR then operate, A, B release, and the call is held from the operator's position by ground fed back over wiper P to relay AR. Call to sub-satellite. For a call from a satellite subscriber to the associated subsatellite, relay BW operates over the incoming P-wire to switch through to the junction. For a call from the main exchange to the subsatellite, relay SW is operated followed by SR which switches through and connects in the neon-lamp bridge.