运动小孔径水平基阵估计目标深度

Source depth estimation using a small-aperture horizontal moving array

针对浅海动态声场,基于简正波模型提出了一种利用运动小孔径水平基阵估计目标深度的方法。通过合成孔径算法将运动小孔径水平基阵扩展成虚拟的大孔径水平基阵,利用稀疏近似最小方差准则可以在相对较小的合成孔径上估计各阶简正波模态能量,不同深度的模态匹配度由Camberm距离的负指数度量,目标深度估计结果是模态匹配度最大值对应深度。数值仿真与实验结果表明,在简正波声场结构基础上,声源频率越低则实现目标深度估计需要的合成孔径距离越小,当声源与阵列端射方向成一定角度时,对所需合成孔径的影响与其相对速度变化时的影响相同,在典型浅海水平分层波导中,当单阵元输入信噪比为10dB时,准确估计200 Hz和350 Hz声源的深度,分别要求合成孔径大于12倍和16倍波导深度.利用实验数据验证了该方法对水下低频线谱声源的深度估计能力。

For the source depth estimation in shallow water,considering the normal mode theory which indicates the information of the depth that the depth information of the source and receiving hydrophones is contained in the modal energy distribution,an approach using a small-aperture horizontal moving array has been proposed.The normal mode model for the signals received by a horizontal moving array in the shallow water dynamic sound filed has been established and the real small aperture of array is expanded into a virtual large aperture using synthetic aperture algorithm.The sparse asymptotic minimum variance criterion was used to estimate the modal energy distribution.The negative index of Camberra distance was used to calculate the mode matched degree,which indicates the probability distribution of the source depth.Both simulations and experiments showed,based on the sound field structure of the normal mode theory wave model,the lower the source frequency,the smaller the synthetic aperture distance required to achieve estimate the source depth estimation.When the sound source is at a certain angle from the end-fire direction of the array,the effect on the required synthetic aperture is the same as that when the relative velocity changes.In a typical shallow-sea stratified waveguide,when the signal-to-noise ratio is 10 dB,the depth of the 200 Hz and 350 Hz sound sources is accurately estimated,and the synthetic aperture is required to be greater 12 times and 16 times the depth of the waveguide,respectively.