利用水平阵模态域波束形成判别声源深度*

针对近水面声源和水下声源的深度判别问题，根据近水面声源难以激发低阶模态的物理现象，研究利用声源波数谱结构和波数位置的不同来分辨近水面声源和水下声源。通过采用MVDR的谱估计方法进行模态域波束形成，补偿水平阵各阵元之间各号简正波的相位差，获得主瓣窄、旁瓣低的声源信号波数谱。波数谱的波数位置与频率呈近似线性关系，水中声速剖面、海底参数、海深都会影响波数谱的具体结构和位置。此外，声源信号的到达角估计误差同样也会影响波数谱主瓣的位置估计。数值仿真结果表明，在浅海负跃层声速剖面条件下，可利用水平阵模态域波束形成判别声源深度，区分近水面声源和水下声源。

Source depth discrimination based on beamforming in modal domain by a horizontal array

In order to distinguish the depth of the near-surface sound source and the underwater sound source, according to the physical phenomenon that the near-surface sound source is difficult to excite low-order modes, the identification of the near-surface sound source and the underwater sound source is studied by using the difference of wavenumber spectrum structure and wavenumber position of sound sources. The spectrum estimation method of MVDR is used to beamforming in modal domain to compensate the phase difference of the modes between the elements of the horizontal array, and the wavenumber spectrum of the source signal with narrow main lobe and low side lobe is obtained. The position of wavenumber of wavenumber spectrum is approximately linear with frequency. Sound velocity profile, seabed parameters and sea depth will affect the specific structure and location of wavenumber spectrum. In addition, the DOA estimation error of the source signal also affects the position estimation of the main lobe of the wavenumber spectrum. The numerical simulation results show that in the case of negative thermocline of shallow water, the horizontal array modal domain beamforming can effectively distinguish the sound source depth, and distinguish the near-surface sound source from the underwater sound source.