水声信号稀疏重构高分辨角度-多普勒成像

针对傅氏空时二维谱估计分辨率低以及声呐空时采样数据样本数不足给角度-多普勒成像带来困难的问题,提出一种水声信号稀疏重构的高分辨角度-多普勒成像方法和抗混响空时滤波器的稀疏重构方法。该方法在声呐阵列单测量向量的极少观测样本条件下,建立阵列信号的空时稀疏表示模型,应用稀疏表示的匹配追踪算法和基追踪算法重构回波与混响的高分辨角度-多普勒像。并根据运动声呐回波与混响的空时分布规律及声呐待检测距离单元位置的先验信息,沿着混响空时分布脊线设计混响稀疏表示的专用空时导向向量字典,通过重构抗混响空时滤波器来抑制角度-多普勒平面的混响干扰。对运动声呐前视和侧视阵列的计算机仿真结果表明,在混响背景中,该方法采用声呐阵列单测量向量重构了低速运动目标多亮点回波的高分辨角度-多普勒像,频率分辨率突破傅里叶分辨率,角度分辨率突破阵列瑞利限,分辨率明显优于傅氏空时谱估计。 

High-resolution angle-Doppler imaging by sparse recovery of underwater acoustic signals

The low resolution of Fourier 2-D spatial temporal spectrum estimation and the insufficient sample size of sonar space-time sampling data often caused difficulties in high-resolution space-time spectrum estimation.Aiming to solve this problem,we proposed a high-resolution angle-Doppler imaging method and designed an anti-reverberation space-time filter based on the sparse recovery of underwater acoustic signals.The proposed imaging method established the spatio-temporal sparse representation model of array signal under the condition of few observation samples of single measurement vector,and reconstructed the high-resolution angle-Doppler image of echo and reverberation through the matching pursuit algorithm and base pursuit algorithm.By utilizing the space-time distribution characteristics of echo and reverberation and the prior information of sonar rangecell under test,a reverberation dictionary composed of special space-time guidance vectors was designed,and was used to reconstruct the reverberation and formed an anti-reverberation space-time filter to suppress the reverberation interference of angle-Doppler plane.Computer simulations indicated that,under two conditions of forward and side-view array of moving sonar,the single measurement vector of sonar array was successfully used in the reverberation background to reconstruct the high-resolution angle-Doppler profile of low-speed moving target multi-spot echo.Its frequency resolution had a better performance than the Fourier resolution and the angle resolution broke through the Rayleigh limit of the array,the resolution was obviously superior to the Fourier space-time spectrum estimation.