Patent GB-290362-A (GB)
Title: Improvements in automatic or semi-automatic telephone systems
IPC: H04Q3/42
Filed: 1927-02-12
Abstract: 290,362. Standard Telephones & Cables, Ltd., Wright, E. P. G., Cameron, A. H., and Chanter, A. J. Feb. 12, 1927. Automatic and semi-automatic exchange systems.-In a system employing register-controllers of the code-translating type, a common set of sending switches MS, NS, VS, WS is provided for the group of registercontrollers, and a switch SFS operates before each digit is sent to connect up one of the sending switches. A common distributing frame is employed. The sending switches are constantly rotating, and are seized over their own bank terminals in one of two positions according to the pause necessary before the actual transmission of impulses, which starts when a certain position is reached. For example, only a short pause is necesary in the case of the first digit, and in the case of the digit following a positive holding up of the sending in certain contingencies. In order to reduce the hunting time of the switch SFS, the wipers of the sender switches are arranged in different relative positions. The sending operation is controlled by an additional switch SS which rotates six times as fast as the sender switches. The switch SFS may be replaced by a group of relays. Normal call. When the register-controller is seized, line relay A and release relay B energize, and the impulse springs LSI, LS2, are tested as described in Specification 256,300. If they are operating correctly, relays LC1, LC2 pull up, and the control switch SC- moves to position 2. When two exchange digits have been registered, the digit distributing switch DD moves to position 3, and the magnet R8 operates to step the switch SFS at a speed five times that of the sender switches, test relay SF being connected to wiper F, the terminals of which are connected to the 11th and 23rd terminals of the sending switches. Assuming the switch WS to be the first to reach position 11 or 23 relay SF energizes and stops the hunting motion. When the switch WS reaches position 14 or 1, starting relay SA energizes and locks and connects impulse springs LS2 across the out-impulse wire. The springs LS1, LS2 are used alternatively according to which pair is closed when the starting circuit is completed, and discrimination is effected by means of relay SQ, which energizes over wiper Q when either of the switches MS, NS is taken into use. Relay SF falls back. Assuming the first translated digit to be 6, impulses are sent out until the switch WS reaches position 20 or 7 when a circuit is closed over the distributing frame and wiper WP1 of the office register for stopping relay, SZ which locks, short-circuits the impulse springs, and disconnects relay SA. Relay SQ energizes (if not already operated) and the control switch SC moves to position 3. The switch SFS operates again, but test relay SF is now connected to wiper S, the terminals of which are connected to the 6th and 18th terminals of the sending switches. Accordingly a sending switch is seized in position 6 or 18, and a pause ensues until the switch reaches position 14 or 1. The impulse sending continues in a similar manner, and after the units digit has been sent, the switch SC moves to position 12, relay CO energizes over terminals COB, locks and disconnects release relay B. Routing code with less than six digits. The ineffective wipers of the office register are connected to strip terminals DCO over which impulses are sent by way of relay W over terminals of the switch SS to advance the control switch SC through the corresponding positions. Non-numerical calls. The first of the ineffective wipers of the office register is connected over to terminals 'COB, so that relay CO energizes and releases the register controller. Call to coder call indicator. In this case, when two successive hunting movements have to be made, relay D energizes due to the reversal of current over the out-impulse wires, and disconnects relays SF, SQ and the magnet R8 to stop the sending operations. When relay D is released, a sending switch is taken into use in position 11 or 23, so that only a short pause occurs before the next digit is sent. Sending operations overtake dialling operations. For example, if the tens digit has not been registered when the control switch SC moves to position 10, relay SQ falls back and only a short pause occurs when sending is resumed, as described in the last paragraph.