Research On Key Technologies For Active Detection Of Sonar Signal Processing On Small Platforms

With the development of science and technology,detection sonar technology based on small platforms such as underwater unmanned aerial vehicles has become increasingly important.The active sonar mounted on a small platform has problems such as small array size and limited signal transmission capabilities.In this case,the target orientation estimation cannot meet high resolution and the signal-to-noise ratio of the echo signal is low,so the detection performance of the sonar system becomes poor.In view of the above problems,this article studies the design of active sonar emission waveforms and their echo signal detection methods,and the virtual array expansion technology based on vector arrays.The main research contents are summarized as follows:Firstly,the characteristics of three typical comb-spectrum signals are analyzed,and the waveform design of comb-spectrum signals is optimized for the problem of peak-to-average power ratio of comb-spectrum signals.The fuzzy function is used to analyze the anti-reverberation ability and time-frequency resolution of three traditional comb-spectrum signals,such as SFM signal,PTFM signal and GC signal.In addition,in view of the problem of the peak-to-average power ratio of the GC signal,from the perspective of spectrum shaping,an optimized design method of low peak-to-average power ratio comb-spectrum waveform based on alternating projection is studied.The time-frequency resolution,anti-reverberation ability,distance sidelobe level performance of the GC waveform generated under a specific PAPR and the anti-reverberation performance of the GC waveform generated under different PAPR are simulated and analyzed.And effectiveness.Secondly,in view of the limited aperture of small platform arrays,the virtual array expansion method based on fourth-order cumulant and the virtual array expansion method based on interpolation transform are studied and extended to vector array.The performance of the virtual extended array is analyzed from the perspectives of spatial spectrum,angular resolution,and azimuth estimation accuracy,and the effectiveness of the two virtual array extended methods is verified.Finally,the comb-spectrum signal detection method with low sidelobe matched filtering is studied.Comb-spectrum signals have relatively high side lobes after matching filtering.To solve the problem that the high side-lobes of comb-spectrum after matching filtering may overwhelm the adjacent weak target main lobes,the research based on deconvolution and An iterative weighted least squares sidelobe suppression method.The research results show that both methods can effectively achieve sidelobe suppression and improve the detection performance of weak targets submerged by strong targets.