Patent ID: 7340012

Claim:
A method for decoding information from a substantially sinusoidal waveform containing encoded digital data at selected phase angles θ n , the waveform having an amplitude Y=sin θ at phase angles lying outside of data regions, the waveform having an amplitude Y=sin θ at phase angles lying inside the data regions having a range of Δθ beginning at each phase angle θ n where data of the first value is to be encoded, the waveform having an amplitude Y defined by a function different from Y=sin θ at phase angles lying inside the data regions having a range of Δθ beginning at each phase angle θ n where data of the second value is to be encoded, comprising: receiving the sinusoidal waveform containing encoded digital data; generating a reference sinusoidal waveform from said substantially sinusoidal waveform containing encoded digital data, said reference sinusoidal waveform having a constant phase relationship with said sinusoidal waveform containing encoded digital data; mixing said reference sinusoidal waveform and said substantially sinusoidal waveform containing encoded digital data in a balanced mixer; extracting said encoded digital data from said balanced mixer; detecting zero-crossings of one of said sinusoidal waveform and said reference sinusoidal waveform; and generating a sync signal from the detected zero crossings.