A method for signal transmission via lines of an alternating current - said distribution network

摘要

1322461 Selective signalling LANDIS & GYR AG 26 May 1971 [11 June 1970] 17324/71 Heading G4H Signals are transmitted over the conductors of an A.C. distribution network by superposition of pulses of audio-frequency oscillation, the length of the superposed pulses lying within the range from one-eighth of a period to a whole period of the network A.C. voltage, a frequency band corresponding to the entire transmission range of the network above the A.C. fundamental being used, and the harmonics of this fundamental being filtered out. At a receiver, the pulses are passed by a high pass filter which blocks the A.C. fundamental and a comb filter which blocks its harmonics, a start pulse triggering a monostable to gate the other pulses and shift pulses derived from the A.C. to a shift register. If a diode matrix recognizes a particular address and order in the register, a relay is energized to carry out a desired switching operation. Measurement valves or meter conditions can also be transmitted.