Research On The Adaptive Beamforming With Vector Array

The port channels,island fortresses and our important military facilities are key areas for the enemy's submarines to conduct blockade operations.In order to break through the blockade and safeguard security,it is necessary to realize long-range early warning detection of enemy submarines.The main purpose of shore-based vigilance sonar is to achieve security awareness in important areas.The early shore-based sonar is composed of scalar long linear arrays.With the development of vector hydrophone technology,vector shore-based sonar composed of vector hydrophones has higher detection capability and detection efficiency.Compared with the conventional sound pressure hydrophone array,the vector array can obtain more independent channel data with the same number of array elements,which brings greater array gain,left and right resolution,and side lobe suppression for vector array signal processing.Vector array brings a series of problems while bringing various advantages.1.The long line array uses the large aperture of the array to achieve higher detection accuracy,but high resolution limits the integration time available in signal processing.At this time,the resulting data covariance matrix is often disproportionate.Therefore,the performance of the adaptive beamforming algorithm will be affected.The number of independent data channels of the vector array is 4 times that of conventional sound pressure arrays.This brings considerable array gain to the vector array and also increases the dimensions of the covariance matrix,which also leads to an increase in the number of geometric quantities that can be calculated.This is not tolerable in real-time processing systems.2.The steering vector of the matrix is composed of the steering vector of the vector channel and the steering vector of the sound pressure channel.The error source for each steering vector is often different.When a tolerant adaptive beamforming algorithm is applied to a vector matrix,how to design different steering vector error constraints becomes a new problem.3.The main purpose of the shore-based vigilance sonar is to detect underwater dangerous targets that are unfavorable to us.Therefore,close-range surface vessels are uninteresting interference targets,but surface vessels will severely reduce the efficiency of early-warning detection of underwater targets based on alert sonar.4.In underwater acoustic communication(UWAC)channels with limited frequency band resources,code division multiple access and space division multiple access are the most considered multiple access methods.When the user's capacity is large,the number of pseudo-random sequences is limited becouse of the order of the pseudo-random sequence of Code Division Multiple Access(CDMA)is low.At the same time,the single-channel receiver has a low SNR,and the channel equalizer is susceptible to the space-time changes in the channel.The paper will use the vector array adaptive beamforming algorithm to solve the above problems faced by UWAC.In the research process,this paper uses the shore-based vector array sonar as the background.Based on the existing research results,content such as tolerance adaptive beamforming,strong interference suppression,vector signal processing,etc.Explore ways to improve detection performance,interference suppression capability,and passive communication of shore-based vector array sonar.First,on the basis of MVDR,RCB,and other algorithms,the application of adaptive beamforming algorithm in the case of limited data is studied.An improved RCB algorithm suitable for long linear arrays is proposed,and the performance of the algorithm is compared with the traditional methods.The advantages of this method are as follows:(1)When the data snapshot is limited,the RCB algorithm retains the features of high resolution,strong interference suppression,and high tolerance;(2)Since the algorithm uses singular value decomposition instead of matrix inversion,the algorithm has a small amount of calculation and it is suitable for engineering applications.Secondly,in view of the problems of the shore-based vector array sonar combined with the characteristics of the vector hydrophone,three adaptive beamforming algorithms are proposed in this paper.One is to expand the scalar modified RCB algorithm into vector arrays;The second is the use of vector hydrophone array weighted vector features,it can be divided into array weight vector and vector weight vector,for different situations choose appropriate weight vector for azimuth estimation,and then proposed a vector weight decomposition RCB algorithm.The third is to combine vector-based decomposition RCB algorithm with beam-domain beamforming theory,and propose a beam-domain vector weight decomposition RCB algorithm.In the case that the performance of the algorithm is not greatly lost,the amount of system operations is greatly reduced.The performance of various algorithms was analyzed by simulation data.By using the sea trial data to compare and analyze each algorithm,it can be proved that the vector weight decomposition RCB algorithm and the beam domain vector weight decomposition RCB algorithm have higher processing gain than the traditional algorithm.Thirdly,for the problem that the shore-based vector array will be plagued by a large number of near-distance strong interference targets in practical applications,this paper proposes a strong interference based on broadband target screening based on MRABF strong interference suppression algorithm.The algorithm solves the problems of unresolved ocean channel fluctuation and target radiation noise frequency distribution characteristics in the MRABF algorithm,and improves the stability and practical availability of the algorithm.The data simulation proves that the algorithm can suppress strong interference with a difference of 35 dB.In order to prove the versatility of the algorithm,combined with the test data of the triplet side array sonar,the strong interference and disturbance in the wake region are suppressed.Finally,the application of vector array signal processing method in underwater acoustic communication is studied.Mainly for the horizontal long line array type and vertical array type,using RCB adaptive beamforming algorithm for robust beam output,using the processing gain of the horizontal long linear array to increase the working distance of underwater acoustic communication,and based on the characteristics of the long linear array with high azimuth resolution,combined with the M-ary spread spectrum underwater acoustic communication system.The multi-user underwater acoustic communication of code division multiple access combined with space division multiple access is realized,and the user capacity of underwater acoustic multi-user communication is improved.In addition,beamforming is performed in the vertical direction in the form of a vertical array,and the idea of spatial filtering is used to suppress the multi-path channel.The complexity of demodulation and channel equalization at the receiving end of the underwater acoustic communication is simplified,and the application basic research is completed.