Patent ID: 8472564

Claim:
An automatic zero-crossing signal demodulation and classification device for rapidly identifying an unknown modulation in a signal, comprising: a normalized digitized intermediate frequency (IF) phase-shifted keying signal f(k) is sent to a sample delay circuit and a symbol timing circuit; said IF signal having an amplitude, a plurality of random amplitude fluctuations at multiple zero crossing points, a susceptibility to random noise, an unknown center frequency fc and an unknown modulation; said sample delay circuit produces a delayed signal fed into a differential phase estimator; said differential phase estimator having a plurality of zero-crossing counters and a means for differential phase shift keying; said symbol timing circuit, having a means for DC bias sends a symbol timing input to said differential phase estimator and converts said IF signal to a sinusoidal signal g(k); said sinusoidal signal g(k) is shifted to said DC bias means and is converted into a square waveform output gs(k); said differential phase shift keying means codes said symbol timing input; said differential phase estimator calculates a time difference value between a plurality of zero-crossing samples and converts said IF signal to a rectangular waveform fs(k) having a time delay, said time delay synchronizes a plurality of zero-crossing points of a timing waveform g(k); said differential phase shift keying means demodulates said delayed signal and said symbol timing input and said differential phase estimator provides a differential phase output to a means for generating an estimated phase histogram; said histogram generating means generates an estimated phased histogram and evaluates a plurality of statistical patterns to determine a plurality of modulation types; a means for histogram comparison compares said estimated phased histogram to said plurality of known templates from a histogram storage module to determine an optimal match; and said histogram comparison means provides a comparison output to a modulation type module, said modulation type module rapidly develops an increased accuracy modulation output that identifies said unknown modulation for a user on a display means.