海底掩埋物下视合成孔径三维成像方法研究

Downward-looking 3D Imaging Method for Buried Objects in the Seabed

受海底沉积层回波影响,掩埋物探测及成像难于实现,针对此问题本文提出一种基于平面阵的合成孔径下视三维成像算法,该算法采用平面阵合成孔径处理方法,可以有效地提高沿航迹方向的成像分辨率。与此同时,垂直航迹方向通过基于实孔径阵列的常规波束形成实现目标成像。仿真实验表明:基于平面阵的合成孔径下视三维成像算法沿航迹方向的成像分辨率依赖于合成孔径长度及信号的中心频率,沿航迹方向信噪比随着合成孔径长度增加而增加。另一方面,垂直航迹方向分辨率随测绘高度的增加而明显下降。采用沿航迹方向单排阵元的简化平面阵声纳进行浅海海域掩埋线缆目标的海试试验并处理了海试数据。处理结果显示,在现实的浅海水域环境下,采用平面阵布阵方式的合成孔径下视成像声纳可以对海底掩埋目标进行有效成像。

Echoed sonic wave generated by the sediments will interfere the expected back-scattering signal,which makes it more difficult to achieve acoustical image of buried objects,compared with those just in the water.The downward-looking three-dimensional underwater acoustical imaging algorithm using synthetic aperture processing based on planar array is presented to improve the performance of buried object imaging in along-track direction.Meanwhile,conventional beam forming(CBF)based on real-aperture array is applied to the across-track direction.The simulation results show that the along-track resolution is dependent on the length of the synthetic aperture and center frequency.The SNR of image in along-track direction improves with the increase of the length of the synthetic aperture.While the across-track resolution degrades with the increase of depth of the objects.One single line of along-track array was applied to real marine environment and the sea trial data was processed to verify the effectiveness of the algorithm.The sea trial result shows that SAS based on planer array can image the buried liner object in the seabed.