Patent GB-354821-A (GB)
Title: Improvements relating to electric signalling arrangements adapted to be used in telephone systems
IPC: H04Q1/38
Filed: 1930-05-15
Abstract: 354,821. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, and CHRISTIAN, D. A., Morven, Charlton Road, Charlton, both in London. May 15, 1930, No. 14940. [Class 40 (iv).] In electric signalling arrangements, more particularly for automatically associating an operator's key strip with an order wire leading to the required exchange as determined by the group of junctions containing the junction selected by the operator, a transmitting switch is rotated synchronously with a receiving switch and is adapted to apply to signalling conductors, potentials characteristic of the signal to be transmitted, to operate through the receiving switch a corresponding combination of relays. In this manner the relays may mark an order-wire finder switch in response to a signal transmitted over a cord circuit from a transmitting switch common to the group of junctions containing the junction selected by the operator. The transmitting and receiving switches may be mechanically coupled. The Figures show the invention applied to key-sending arrangements for use by " A " operators in a telephone system. The transmitting switch comprises wipers 5 . . 8 common to a group of junctions and adapted to control the transmission of a signal characteristic of the group to receiving relays CA .. CF, over a cord circuit and a receiving switch comprising wipers 1 .. 4 which are common to all the cords at a position. On receiving a call for a distant exchange the A operator makes the usual test and plugs into a free junction jack JJ, Fig. 2. Relays M, H operate (N remaining inoperative owing to the high resistance of H), relay M on disconnecting the testing apparatus whilst relay H prepares Swhich is operated and locked up when wiper 7 engages its earthed segment. Relay S short-circuits H to cause operation of N which disconnects the speaking key SK and connects the plug to wipers 3, 4. The jack also is connected to wipers 5, 6 and transmission of the signal is initiated. During rotation wipers 5, 6 transmit impulses over the cord circuit and corresponding relays CA, CE, CF are operated and locked up to mark the appropriate contact in the bank OF1 of the order-wire finder over chain contacts ca2 .. cf2. When wiper 8 engages its earthed segment relay z is operated and relay is released, the outgoing junction circuit being closed and the short-circuit across H being removed to permit release of N and the reconnection of the plug to the speaking key. Earth is then connected over wiper 1 to operate relay CH which energizes relay E, disconnects wipers 3, 4 from the cord circuit and illuminates lamps CL, SL. Relay E prepares circuits of relay T and stepping magnet DM and connects relay P to the key SK. Consequent upon the release of relay N, line relay at the incoming end of the junction is operated over the b wire and marking is effected in the banks of the junction finders and switches associated with the incoming end of the order wire are taken into use to search for the marked junction and for an idle register sender. When both of these have been found and an association of the order wire and junction is made, battery is connected to the a wire and the wire on of the order wire conductor. When lamp CL lights, the key SK is operated to connect the operator's instrument to the cord and relay P is operated over the a wire. Relay P operates F which closes the stepping circuit of magnet DM to drive the order-wire finder up to the marked contact when relay T is energized to prevent further stepping and effect connection cf the digit keys DK to the order-wire over wipers OF3 .. OF6 of the finder. Lamp SL also is extinguished to signify that digit transmission may be effected. When the number is registered at the distant exchange, battery is disconnected from wire on and T releases to effect disconnection of the digit keys and allow operation of relay LCO over wiper. 2. Relay LCO effects release of the operated relays CA .. CF and relay CH, to restore the equipment to normal condition. After conversation the operator withdraws plug and effects release of relays M, H. The equipment may be restored to normal at any stage of operation by actuation of key RK. If an impulse sender is located at the outgoing end of the junction, the switches 5 .. 8, 1 .. 4 may be utilized for the transmission of the code from the digit key over the cord circuit to digit storing relays in the sender. Synchronously rotated cams operating peripherally arranged contacts may be employed instead of wiper switches. Specifications 296,170, [Class 40 (iv), Telephones &c.], and 352,529 are referred to.