Weak Target Extraction Technology In Strong Interference Based On Array Signal Processing

In the process of modern underwater acoustic detection,due to the complexity of the marine environment,the sonar system is often affected by some strong interference in the work,resulting in poor ability to distinguish the weak target,and even completely obscure the weak target.Therefore,the weak signal from the strong interference extracted,is the field of underwater acoustic exploration is an important issue,it directly affects the follow-up of a variety of processing.In this paper,two kinds of weak target extraction methods are studied on the basis of conventional beamforming and minimum variance error-free response(MVDR).The first is the weak target extraction technique based on multi-objective resolution,which is characterized by the interference and target And the second is a weak target extraction technique based on interference suppression.It suppresses the strong interference by suppressing the beam output of the interfering azimuth signal,so that the weak target is highlighted.The main work is as follows:Aiming at the weak target extraction method of multi-target resolution class,two methods of deconvolution beamforming method and beam domain high resolution algorithm are studied.The output of the deconvolution beamforming is the impulse function of the direction of the signal incidence and therefore has a very narrow main lobe width and a very low sidelobe level.The beam domain high resolution algorithm can suppress interference outside the beam and has a beam-Higher resolution.Then the performance of these two algorithms is analyzed by simulation,including its anti-noise,anti-jamming and resolving performance.Aiming at the weak target extraction method of interference suppression class,the MVDR algorithm and the method of optimizing the beam using second order cone programming are studied.The MVDR method can use the covariance matrix of interference plus noise to construct the weighting vector so that the variance of the interference in the output and the noise is the smallest.Using the second-order cone programming to optimize the beam can make the beam form a nulling in the interference direction,The impact on the signal.Then,the performance of these two methods to suppress the interference is analyzed by simulation,including anti-noise,anti-interference and robustness.Finally,the actual performance of the algorithm for coherent and noncoherent interference suppression is verified by the processing of sea test data.