目标回波时频分布的几何结构图像形态特征

Image Morphological Characteristics of Geometrical Structure of Target Echo Time-frequency Distribution

沉底目标识别的关键在于从混响背景中提取出稳定的目标回波信号特征。目标的棱角散射能够携带目标的几何形状信息,在时频域内具有较规则的分布特性,但是各棱角散射回波声程差小,而且淹没在混响中。已有的时频分析方法局限于其抗混响能力及时频分辨力,为得到一种有效的目标几何特征提取方法,提出将一维几何回波时域信号在二维时频域中的几何分布特征作为图像特征进行特征提取,通过研究几何亮点回波和混响在时频平面上的形态特征,构造与几何亮点时频特性匹配的结构元并对时频分布图像进行形态滤波。通过仿真与湖试数据分析,相比已有方法,文中所提方法能够在实现目标几何亮点结构的识别同时进一步抑制混响。

The key of underwater bottom target recognition is to extract the stable target echo signal fea- ture from reverberation background. The edge scattering of target carries its geometrical information, and it has regular distribution on the time-frequency plane. But the path difference of edge scattering is little, and it＇ s always drowned out by reverberation. Because of the limited time-frequency resolution and the limited anti-reverberation ability of existing time-frequency analysis method, there hash＇ t been any effec- tive feature extraction method of target geometrical characteristics. The geometrical distribution feature of target echo on the time-frequency plane is extracted as an image feature. The morphological characteris- tics of geometrical highlight and reverberation on the time-frequency plane are researched. The structural element matched with the time-frequency distribution is constructed, and the time-frequency distribution image is morphologically filtered. The experimental data processing result shows that, compared with ex- isting method, the proposed method can be used to recognize the geometrical highlight structure of target and suppress the reverberation at the same time.