GB1021833A - Improvements relating to remote control systems - Google Patents

Abstract

1,021,833. Electric selective signalling systems. WESTINGHOUSE BRAKE AND SIGNAL CO. Ltd. May 24, 1963 [May 29, 1962], No. 20621/62. Heading G4H. In a signalling system for transmitting the changes that occur in the positions of a number of switches CS1, CS2 &c., at a control station to a remote station, each change of switch position is registered in one of a pair of triggers 1A, 1B; 2A, 2B; &c. of a main store MS, the main store is scanned continuously by a binary counter BC and a diode decoding matrix DD and each time a " one " bit is discovered in the main store (indicating that a switch has changed its position since the last scan) the scan is temporarily inhibited and the count: in the binary counter BC is transmitted to the remote station, this transmission is serial in groups of three bits under control of a sub-counter SCC and is characterized in that the data is transmitted at least twice differently coded each time until two items are received at the remote station which agree with each other whereupon a comparison circuit CD emits a signal causing the discovered "one" bit in the main store to be reset to zero and the corresponding stage of a register RS to be set to " one." As described, the transmission of the twelve bits in the scanning counter BC is effected in four steps. First bits 1 to 3 are transmitted using three different frequency generators CT 1 , CT 2 , CT 3 , and then the remaining groups of three bits 4 to 6, 7 to 9 and 10 to 12 are transmitted similarly. The second transmission of the contents of counter BC is similar to the first except that the way in which the bits of each group of three bits are associated with the three frequencies is altered. The circuit described only effects one alteration and then returns to the first association but it is stated that a sequence of several alterations could be used.