| 摘要 |
326,252. Associated Telephone &. Telegraph Co. Nov. 28, 1927, [Convention date]. Divide'd on 301,399. Drawings to Specification. Selective distant control and signalling systems. -Relates to a system for the selective operation of apparatus units, such as circuit breakers at a number of substations or signalling devices such as call bells of a train despatching system or the semaphores of a train signalling system. The substations are arranged in parallel across a pair of line wires and selection of any particular unit at a substation is effected by a three-train impulse code, the total number of impulses of the three impulse codes being fixed. The system described is identical with that described in Specification 301,399, but the claims relate to the step-by-step selective switches employed at the substations. Each switch is responsive to the three-train code, selection of any particular device at a substation being effected by the first and second trains of impulses, and operation of the selected device being effected at the termination of the last train which brings the switch into an off-normal position from which it is driven to normal in response to the transmission of a further impulse from the control station. The first train of impulses is also characteristic of the station at whch the device to be selected is located, the switches at the other stations being unresponsive to the second and third trains.
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