Research On Signal Processing For Underwater Acoustic Moving Target Using Phase Characteristics

The detection of underwater acoustic signals with low signal-to-noise ratio(SNR)is a current hot topic in the field of underwater acoustics,and it is also one of the technical problems that have been urgently resolved in the underwater acoustics field.In order to realize the long-distance detection of underwater targets,aiming at the problem of weak signal detection of underwater acoustic targets,this paper studies the long-time cumulative signal processing method based on the phase characteristics.The specific work is as follows:Firstly,the characteristics of the received signal from the moving target are analyzed.The polynomial phase characteristics of the received signal are demonstrated by establishing a mathematical physical model of the moving process of the uniform moving target.The relationship between the coefficients of the time term of the received signal and the parameters of the moving target is derived.Through simulation,it is shown that the long-term cumulative received signal of moving target can be approximately described by polynomial phase characteristic signal of finite order.The theoretical analysis shows that the received signal of the moving target in the ocean waveguide which described by the normal wave theory still has the polynomial phase feature.Secondly,research on signal detection for moving target using the local polynomial Fourier transform.The local polynomial Fourier transform is derived theoretically.The fast algorithm of local polynomial Fourier transform is improved,and the amount of calculation is reduced,Through theoretical derivation and numerical simulation,and compared with the traditional Fourier transform,it shows that the fast algorithm of local polynomial Fourier transform has excellent polynomial phase signal processing ability,time-frequency clustering,and has a restraining effect on cross terms and noise.The validity of the fast algorithm of local polynomial Fourier transform method for the processing of moving target signal is verified by sea test data processing and analysis.Finally,research on signal detection for moving target using matched Fourier transform.The matching Fourier transform method is derived theoretically,and the second-order matching Fourier transform and the two-step matching Fourier transform are studied.Numerical simulation analysis and comparison with traditional Fourier transform and the fast algorithm of local polynomial Fourier transform prove that the matched Fouriertransform has excellent polynomial phase signal processing ability,time-frequency aggregation,and suppression effect on cross term and noise.The validity of the matching Fourier transform method for moving target signal processing is verified by sea test data processing and analysis.