Time-Frequency High Resolution Separation Of Underwater Target Acoustic Scattering Signal

Using the active sonar to detect and identify the underwater quiet small target,the time-frequency characteristic of the target acoustic scattering is studied by various time-frequency analysis methods,which has been an important subject of underwater acoustic signal processing.In the case of using LFM(LFM)signal as the transmission signal condition,the underwater target acoustic scattering signal is mixed with each other in the time-frequency domain.Therefore,it is the focus of this paper to accurately isolate the signal characteristics of the underwater target acoustic scattering echo.In this paper,the physical acoustics method is used to solve the analytic solution of the acoustic field of the underwater target.The bright spot model is used to analyze the acoustic scattering signal structure of the underwater target.The geometrical acoustic scattering echo characteristics of the hemispherical cylindrical shell are deduced theoretically.The variation law of delay parameters is changed with the angle of incident wave.Based on the traditional time-frequency analysis method,the time-frequency characteristics of single bright point echo and multi-bright echo are analyzed emphatically.The reason of quadratic time-frequency analysis method,such as WVD and ambiguity function,is explained.According to the principle of Cohen class time-frequency distribution,this paper uses a time-frequency analysis method based on radial kernel function.By using the difference of self-term and cross term in the fuzzy domain,the ambiguity function is used to solve the radial function The radial angle is used to design the radial kernel function.Finally,the signal autocorrelation matrix is estimated based on the time-frequency analysis results,and the two-dimensional MUSIC spatial spectrum estimation is realized.According to the actual background of the underwater target detection,the stable feature extraction is realized for the geometric acoustic scattering signal.In this paper,the time-frequency analysis method based on radial kernel function and Chirp MUSIC spatial spectrum estimation algorithm are used to realize the separation of underwater target geometric acoustic scattering signals.The results show that the proposed method has good time-frequency aggregation performance and achieves the purpose of suppressing the WVD cross-term,and it also has a certain effect on the noise and effectively improves the signal-to-noise ratio.The experimental results show that the method can effectively separate the geometric scattering components in the underwater target echo.At the same time,the results show that the method has some anti-interference ability for reverberation,The feasibility of using the radial kernel function time-frequency method to separate the underwater target acoustic scattering signal is verified,which lays the foundation for realizing the underwater target active sonar detection and recognition.