Research On Anti-principal Flap Interference Method Of Hydroacoustic Array Signal Based On Adaptive Beam Formation

With the advancement of the ocean power strategy,a large number of electronic devices have emerged to process underwater information.As one of the main instruments for exploring the ocean,hydroacoustic transducer arrays can effectively improve the quality of the received signal.Adaptive Beamforming(ADBF)technology is an important aspect of array signal processing and can effectively eliminate side flap interference signals from the received signal.When the interference signal falls within the main beam,the ADBF technique suppresses the interference signal by forming an internal trap in the direction of the main flap,resulting in a deformation of the main beam in the beam response diagram.However,in the case of high intensity of main flap interference and the presence of the desired signal in the sampled data,the traditional anti-main flap interference algorithm will have the problem that the main flap interference eigenvector is not easily distinguishable and the desired signal is selfcancelling,resulting in shallow internal trapping of the side flap interference signal and reduced Signal to Interference and Noise Ratio(SINR)of the output signal.In this paper,we propose an anti-interference algorithm based on the projection matrix and grey wolf optimization for the complex marine environment channel under the BELLHOP model,which can effectively suppress the interference signal and improve the SINR under the premise of high intensity of the main flap interference and the presence of the desired signal in the sampled data.The main work accomplished in this paper is as follows:(1)A covariance construction method based on spectral estimation is proposed for the problem that the main flap interference signal is not easily distinguishable due to the variable strength of the main flap interference signal in the complex ocean environment and the problem that there may be useful signals in the sampled data causing the desired signal to self-cancel.The method firstly finds the covariance matrix of the angle region of the main flap interference signal according to the characteristics of the spatial power spectrum amplitude by using spectral estimation and integration of the power spectrum,secondly decomposes the eigenvalues of the covariance matrix,calculates the eigenvector corresponding to the maximum eigenvalue of the covariance matrix and the eigenvector obtained from the eigenvalue decomposition of all signals plus noise covariance matrix,which can extract the eigenvector corresponding to the main flap interference signal more accurately,and then uses this eigenvector to construct the eigenprojection matrix to achieve the effect of accurate suppression of the main flap interference signal,and the suppression effect is not easily affected by the intensity of the interference signal.In addition,the covariance matrix of the angular region of the desired signal is also obtained by using the spectral estimation and integration of the power spectrum,and the covariance matrix is eliminated from all the signal plus noise covariance matrices to obtain the interference plus noise covariance matrix.Beamforming using interference plus noise covariance matrix will effectively solve the problem of self-cancellation of the desired signal.(2)In order to solve the problem of weakened suppression effect of side flap interference signal and main beam deformation caused by high intensity of main flap interference signal,a method based on the improved grey wolf optimization algorithm is proposed to optimize the weight vector,firstly,the performance of the improved grey wolf optimization algorithm is verified by the benchmark function,secondly,the output signal to dry noise ratio is designed as the fitness function of the improved grey wolf algorithm,and the improved grey wolf optimization algorithm is used to find the weight vector that makes the output signal to dry noise ratio highest,optimize the beam formation weight vector,make the highest gain of the main beam of the array beam response map point to the desired signal,deepen the zero trap at the side flap interference direction,and improve the output SINR.(3)Simulation to verify the effectiveness of the anti-principal flap interference algorithm based on projection matrix and gray wolf optimization.In this paper,we simulate the model of hydroacoustic channel by BELLHOP toolbox,and conduct simulation experiments based on the model,using the calculated correlation value,output signal-to-noise ratio and beam direction diagram as the evaluation index of the anti-dominant flap interference algorithm.In the case of three interference-to-noise ratios,the proposed algorithm improves the correlation calculation difference by at least 0.638 compared with the traditional method,and the output signal-to-noise ratio improves by at least 3.054 d B compared with the four anti-principal flap interference algorithms.It is proved that the proposed algorithm has better performance in antiprincipal flap interference.In summary,the algorithm proposed in this paper can eliminate the problem of self-cancellation of the expected signal,effectively suppress the interference,and improve the output signal-to-noise ratio,effectively improve the reception quality of the hydroacoustic array signal in the complex marine environment where the main flap interference strength is variable and there is a useful signal in the sampled signal,and provide some theoretical support to promote the development of underwater wireless transmission system,both theoretical value and practical application value.