Study Of Modulation Identification And Signals Feature Extraction

Automatic modulation identification is widely used to confirm the interference identification, radio interception, electronic countermeasures, and signal detection, and other fields. This paper provide some mothodes to detect the AM, MASK, MFSK, MPSK signals, and also give parameter estimation methods.The method used in modulation identification based on the signal peaks and the number of signal frequency. The identification method to analyze the analog signal is based on the instantaneous characteristics of signals and to the digital signal is based on the rate, frequency, and the higher-order statistics, constituting Digital signal recognition methods. Use the autocorrelation function to get the power spectrum, and get the carrier of the signal. Through the relationship between the bandwidth and the symbol rate, symbol rate is obtained.The simulation with Matlab proved the theoretical validation and the advantage of the higher-order statistics in the modulation recognition. Finally, use the Matlab wavelet toolbox, which choosed haar wavelet function and db3 wavelet function to analyze the 8 PSK signal and 4FSK signal. The wavelet analysis methods can detect the phase transition point of 8PSK signal and the signal component with differtent carrier, but the analysis result is sereously affected by the choice of wavelet function.