基于测深侧扫声呐的DOA估计算法研究

Research on DOA estimation algorithm based on bathymetric side scan sonar

针对测深侧扫声呐进行波达方向(Direction of Arrival,DOA)估计时会受到阵元幅度、相位误差及低信噪比影响的问题,提出一种改进的波束域加权子空间拟合算法。首先,采用总体最小二乘-旋转不变子空间算法进行回波方向预估计;其次,将连续线阵划分为多个子阵,并将各个子阵在预估计方向做加权波束形成;再次,采用加权子空间拟合(Weighted Subspace Fitting,WSF)算法构造代价函数;最后,采用阻尼牛顿法求解得到高精度的DOA估计结果。仿真结果表明,文中所提算法在阵元出现幅度相位误差条件下的角度估计均方误差相对于WSF算法减少了约0.03°。海试数据分析结果表明,文中所提算法的测深点均方误差整体优于WSF算法,其相对测深精度提高了约9.8个百分点。以上分析结果表明,文中所提算法整体优于WSF算法,可以实现在阵元幅度相位误差及低信噪比情况下的高精度DOA估计。

The direction of arrival(DOA) estimate by bathymetric side-scan sonar is affected by the amplitude-phase errors of array elements and low signal to noise ratio(SNR).For this problem,a modified beam space weighted subspace fitting(MBS-WSF) algorithm is proposed.Firstly,the total least squares-estimation of signal parameters via rotational invariance techniques(TLS-ESPRIT) algorithm is used to pre-estimate the echo direction;secondly,the uniform linear array(ULA) is divided into multiple subarrays,and weighted beamforming is performed for each subarray in the pre-estimated direction;thirdly,the WSF algorithm is used to construct cost function;and finally,the high precision DOA estimation result is obtained by using the damped Newton method.The simulation results show that,the proposed algorithm improves the mean square error of angle estimation by about 0.03° compared with the WSF algorithm in the presence of amplitude-phase errors in array elements.The analysis of sea trial data shows that the mean square error of the proposed algorithm is better than that of WSF algorithm,and its relative bathymetric accuracy is improved by about 9.8 percentages,which shows that the proposed algorithm is superior to the WSF algorithm,and can achieve high precision DOA estimation under the conditions of the array elements with amplitudephase errors and low signal to noise ratio.