Method of automated demodulation and classification of phase-shift-keying signals using hysteretic differential zero-crossing time samples

Abstract

An automatic zero-crossing signal demodulation and classification device for rapidly identifying unknown modulation in a signal identifies unknown modulation in a signal, demodulates differential phase shift keying signals and automatically recognizes certain phase shift keying signals. This is accomplished by eliminating unknown term fin differential phase estimation, introducing a symbol rate tracking mechanism, applying hysteresis nonlinearity to eliminate phase shaping effect and using weighted average to estimate phase difference. Better estimates are accomplished by using hysteretic nonlinear function to detect zero-crossing points in eliminating false detecting of zero-crossing points caused by additive noise, and calculating differential phase without directly using center frequency to simplify estimation process. Present invention also encompasses automated zero-crossing signal surveillance demodulation and classification device for rapidly identifying unknown modulation in a signal and method for automatic zero-crossing demodulation and classification of unknown modulation signal.