BLIND IDENTIFICATION METHOD OF 16APSK MODULATION PATTERN BASED ON POWER SPECTRUM FLATNESS

The invention discloses a blind identification method of 16APSK modulation pattern based on power spectrum flatness, which mainly solves the problem that the signal-to-noise ratio is low due to the long signal transmission distance in satellite communication, thus leading to the high misidentification rate of 16QAM and 16APSK modulation signals. Especially when the signal-to-noise ratio is too low and the sampling multiple is too high, due to the limited amount of data transmitted by satellite communication, the effective feature quantity is relatively small, which makes signal identification extremely difficult. The realization steps of the invention are as follows: 1) signal preprocessing to obtain discrete signal sampling sequence s(n); 2) feature extraction based on the power spectrum flatness to obtain the quartic spectrum flatness plain; 3) completing signal classification identification according to the quartic spectrum flatness plain, and completing frequency offset estimation by using a correction algorithm base on sequence peak energy to obtain the signal modulation type and frequency offset offsetFrep; 4) completing the classification identification and frequency offset estimation of 16QAM and 16APSK signals. On the premise that the signal-to-noise ratio is high than 10dB, the invention quickly and accurately realizes the classification identification and frequency offset estimation of 16QAM and 16APSK signals, the frequency accuracy (the sampling rate is less than 1GHz) can reach 10kHz, and the identification accuracy can reach more than 90%, thus effectively improving the classification identification accuracy of 16QAM and 16APSK signals, providing reliable demodulation parameters for subsequent demodulation work, and being applicable to an integrated communication reconnaissance system.