Patent GB-886663-A (GB)
Title: Improvements relating to remote control systems
Inventor: GROSE BASIL HUBERT
IPC: H03K23/00
Filed: 1957-01-25
Abstract: 886,663. Electric selective signalling systems. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. Jan. 24, 1958 [Jan. 25, 1957], No. 2716/57. Class 40 (1). [Also in Group XIX] In a remote control system, the positions of control devices at the control office are continuously sequentially scanned, and scanning proceeds simultaneously with the scanning of the positions of the controlled apparatus. Counting chain.-A counting chain, Fig. 3, comprises main Eccles-Jordan binary stages EJ1 supplied with stepping pulses over a line SL1 and intermediate stages EJ2 supplied over a line SL2, each stage comprising a pair of crosscoupled transistors, the connections being such that each circuit when reversed primes the immediately succeeding circuit, the pulses on the lines SL1, SL2 being negative interruptions of a normally steady positive potential and supplied alternately so that the reversed condition is advanced down the chain, each circuit remaining in its reversed condition until a resetting operation takes place. Alternatively, there may be only one supply line for pulses delays for alternate application points of the pulses being provided. Connections (not shown) are provided between adjacent stages to enable resetting to proceed down the chain. Stepping pulses.-A single stepping generator in the form of a transistor multivibrator at the control office, Fig. 1, provides pulses for the office chain and also for the field stations over a transmission line LC by means of a carrier frequency f5. The output of the stepping generator is applied to transistor pulse circuits (Fig. 4, not shown) at the control office and field station which produce pulses to be applied to the lines SL1, SL2. Control equipment.-According to the position of two-position control devices, a frequency f 1 or f2 is sent over the transmission line LC, the control devices being sequentially scanned under the control of the counting chain. As shown in Fig. 5, lines SPx, where x denotes one of the counting stages, are connected through control devices CD to a common selector line S which is connected to a selector circuit EJ3 in the form of a bi-stable transistor circuit. The x stage of the counting chain produces a negative scanning pulse on the line SPx which, if the device CD is in the dotted position shown, passes to base of a transistor TR12 and is of such an amplitude as to overcome a synchronous positive pulse on a line ISL, thereby causing the transistor TR12 to conduct and causing a negative potential to be supplied over the line Lf 1. This potential persists during the stepping of the counting chain until a control device CD is reached which is in the full line position. The positive pulse on the line ISL then cuts off the transistor TR12 and negative potential is supplied to the line Lf2 but not Lf 1. The positive pulses over the line ISL may be dispensed with if the circuit EJ3 is replaced by a monostable arrangement. The transmitters f1, f2, Fig. 1, are energized in response to negative potentials on their supply lines Lf 1, Lf2. Registry stages, Fig. 6.-Negative scanning pulses from the intermediate counting chain circuits EJ2 are fed over lines SPR via transistor gates TR13, TR14 which are selectively opened by a negative potential on one only of lines LRf3, LRf4 so that a bi-stable circuit comprising transistors TR15, TR16 is caused to take up one of its stable states. The bi-stable circuit may be arranged to operate a relay when the transistor TR16 is energized (Fig. 7, not shown). Field station, Fig. la.-Relays, called function indication relays, are provided for each item whose position is to be indicated at the control office. These relays are scanned by pulses emitted by the field station counting chain and their positions determine which of two indication carrier frequencies f3 or f4 is transmitted to the control office. Field registry stages are provided in respect of each item whose position is controllable from the control office, and field registry relays associated therewith control the positions of the controllable apparatus. The receivers at the field station and those at the control office are adapted to give an output in the form of a steady negative potential, only in response to the absence of the corresponding frequency on the transmission line LC. Resetting -The control office chain is reset by means of a negative pulse derived from a transistor of the intermediate circuit EJ2 of the last counting stage. Synchronous resetting at the field station is obtained by arranging for an output from the main circuit EJ1 of the last office counting stage to cause the office to transmit both frequencies f1 and f2 simultaneously and by providing a circuit responsive to this unique line condition at the field station (Fig. 9, not shown). Reference has been directed by the Comptroller to Specification 686,829.