Patent ID: 7184937
Filing Date: 2007-02-27
Classification: G01R,H03K,H04L

Abstract:
1. A proportional-delayed zero-crossing estimator device, comprising: a periodic signal, g(x), is sent to a hysteretic nonlinear converter, said signal g(x) having an amplitude, a plurality of random amplitude fluctuations at multiple zero crossing points and a susceptibility to random noise; said converter adds a positive delay threshold, α, and a negative delay threshold, −α, to said amplitude to suppress a plurality of random noise fluctuations; a zero crossing time-difference counter detects a zero crossing time, x(k), whenever said signal g(x)=0; said counter counts a zero-crossing time difference between any two consecutive time samples, x(k) and x(k−1), of the multiple zero crossing points, measures a multitude of pulses from a local oscillator between said two consecutive time samples, reports a current value of a counter output, n(k), and resets to zero in order to count a next state of n(k+1); said counter feeds said counter output to a means for signal repetition-rate estimation, said signal repetition estimation means, having a repetition-rate algorithm, provides a repetition-rate estimate of the signal g(x) to a means for analyzing signal modulation type and a reciprocal operator for frequency calculation purposes; said signal modulation analysis means with the repetition-rate estimation forms a modulation index estimate and a modulation analysis output; said reciprocal operator with the repetition-rate estimation performs a frequency calculation and sends an estimated frequency output to said signal modulation analysis means; said reciprocal operator converts said repetition-rate estimate to an oscillating frequency; said plurality of random amplitude fluctuations at the multiple zero crossing points being removed from said signal g(x); and a means for differentiation receives said estimated frequency output and calculates a frequency difference output, a frequency aging estimate output and an estimated frequency-drift to provide an increased accuracy frequency estimation with a reduced random noise susceptibility.