Load control receiver and method of operation

US4453156A · kind A · utility

Assignee

• Brown, Boveri & Co. AG · CH

Inventors

• Richard W. Brown · Cambridge, US
• Gary Winkler · Minneapolis, US

Key dates

• Filing date: Dec 11, 1981
• Grant date: Jun 5, 1984
• Expiry date: Dec 11, 2001

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B2203/545
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

Method for detecting the presence or absence of an audio-frequency signal (V.sub.T) superimposed on a power supply network, the audio-frequency signal (V.sub.T) having a known frequency (f.sub.T) and an amplitude (A.sub.T) lying within a permissible range of amplitudes (.DELTA.A.sub.T), where the power supply network transmits a signal mixture (V) containing a fundamental (V.sub.g, f.sub.g, A.sub.g), harmonic frequencies (V.sub.H, f.sub.H, A.sub.H) thereof and interference frequencies (V.sub.S, f.sub.S, A.sub.S), which includes, with a microcomputer (M.sub.C), generating a signal at the same point on adjacent waves of the fundamental (V.sub.g); PA1 after the occurrence of a first generated signal (ZCS 1), taking with an A/D-converter (ADC), at equal time intervals (.DELTA.t), a given number (N) of samples (S0) of the voltage (V) on the power supply network, and storing the digital amplitude widths thereof (S0.1, S0.2, . . . S0.N) in a read-write memory (RAM); PA1 after the occurrence of a further generated signal (ZCS 2), taking a further equal number (N) of samples (S1); PA1 forming a digital difference (D) of respective amplitude values (S0.1, S1.1) of the two samples (S0, S1); P…