基于矢量水听器阵列空域预滤波处理的多重信号分类算法研究

矢量水听器能同时拾取声压和振速信息,在相同的信噪比、阵元数及阵列孔径下,矢量阵定向性能优于声压阵列。目前,以多重信号分类算法(Multiple signal classification,MUSIC)为代表的高分辨定向算法已经广泛应用于矢量水听器阵列中。但是随着信噪比降低、信号源方位间隔减小,传统MUSIC算法定向精度及分辨概率显著下降。本文采用最小二乘法设计适用于矢量水听器水平阵列的矩阵空域滤波器,用于阵列数据的空间滤波预处理,可以对阻带扇面噪声进行有效抑制。由滤波后的数据协方差矩阵可以得到新的噪声子空间,在传统MUSIC算法基础上修正通带扇面内阵列流型的畸变后即可得到滤波后MUSIC算法的方位谱。仿真结果表明,当信噪比较低时,改进算法有效提高了通带扇面内目标方位分辨性能。最后本文对四基元矢量水平阵列海试数据进行了处理,改进算法对窄带信号定向较常规算法-3 dB束宽减小了13°,旁瓣级降低约8 dB。对有一定带宽的行船辐射噪声定向处理得到了更加精确的航迹图,海试数据处理结果证明了该算法的可行性和有效性。

Research on spatial prefiltering MUSIC algorithm based on vector hydrophone array

A vector hydrophone can collect both the sound pressure and velocity underwater and the performance of direction of arrival (DOA) estimation for the vector array is superior to the scalar hydrophone with the same signal-to-noise ratio (SNR), array elements and array aperture. Now, high resolution direction finding algorithms, represented by multiple signal classification (MUSIC) algorithm, have been widely used in vector hydrophone arrays. However, the directional accuracy and probability of traditional MUSIC algorithm decreases significantly as signal-to-noise ratio (SNR) decreases and the distance between targets decreases. In this paper, spatial filter matrix which is based on least square (LS) was applied to the vector hydrophone horizontal array. The data of the hydrophone array was preprocessed by this spatial filter, and the noise in the stop band can be suppressed effectively. A new noise subspace can be obtained from the covariance matrix of the data after filtering. Then, the azimuth spectrum of improved MUSIC algorithm can be obtained after modifying the distorted array manifold which is based on the traditional MUSIC algorithm in the pass band. Simulation results show that the improved algorithm can effectively improve the performance of DOA estimation in the pass band with low SNR. Finally, the sea-trial data of horizontal vector array of four elements was processed by the improved algorithm. Compared with conventional algorithm, the -3dB beam width is reduced 13 °, and side-lobe level is decreased about 8dB. A more accurate track plot was obtained from the band ship-radiated noise, which shows that the algorithm is feasible and effective.