Abstract:

The linear frequency modulation (LFM) signal is a kind of important underwater acoustic signal. Under the condition of low signal-to-noise ratio (SNR) and α-stable distributed noise, it is difficult to identify the LFM signal. To sdve this problem, an LFM signal recognition method suitable for low SNR conditions is proposed under shallow sea acoustic multi-channel with impulse noise. In this method, the impulsive noise is suppressed by nonlinear transformation, and then the discrete fractional Fourier transform (DFRFT) is carried out. The recognition feature is constructed by the result of fractional Fourier transform (FRFT). Finally, the identification of the LFM signal is completed by the support vector machine (SVM). The simulation results show that the correct recognition rate is higher than 94% when the mixed signal-to-noise ratio (MSNR) is -15 dB.