水下多途信道下的SAS图像统计特性及成像新算法研究

项目名称： 水下多途信道下的SAS图像统计特性及成像新算法研究

项目编号： No.61062013

项目类型： 地区科学基金项目

立项/批准年度： 2011

项目学科： 金属学与金属工艺

项目作者： 王静

作者单位： 云南大学

项目金额： 8万元

中文摘要： 合成孔径声纳（SAS）是高分辨率成像声纳，与传统声纳一样，会受到水下多途信道的污染，导致成像质量降低。解决多途污染的传统方法是信道建模。但是，实际应用中很难获取建模所需的精确的环境参数，而且，确定性模型很难反映水下信道的随机时变、空变性质。本项目研究SAS图像的统计特性，及水下多途信道对该统计特性的影响，为后续项目消除多途污染、提出新的SAS成像算法、提高SAS 成像质量奠定基础。 本项目通过理论推导、仿真验证、实际SAS图像处理，得出如下主要结论：第一，理想SAS图像的统计特性为呈现厚尾性质的K分布，其形状参数与声纳分辨单元内散射体或者散射斑数量成正比，与声纳接收阵列的波束宽度成正比，与发射波带宽成反比；第二，受多途污染的SAS图像统计特性为K+K混合分布，两个K分布的形状参数分别反映直达波及多途污染的情况。这些结果为进一步研究消除多途污染、提高SAS成像质量奠定了基础，具有重要科学意义。同时，也将服务于云南抚仙湖水下考古、水下地形地貌测绘、水下工程探查等，为地区国民经济建设服务，具有应用价值。

中文关键词： 水下；多途；合成孔径声纳（SAS）；厚尾（heavy-tailed）；统计特性

英文摘要： As with traditional sonar,synthetic aperture sonar(SAS),a kind of high-resolution imaging sonar,is susceptible to multipath contamination,resulting in the reduction of SAS image quality.The propagation channel modeling is the traditional solution for this problem.However, this traditional solution has got several disadvantages:no effective ways to get the necessary accurate environmental parameters and to describe the time and space-varying channel uncertainty with the above certain model. In order to solve the above disadvantages this project studied the related theories,the simulated and practical SAS images and came to the following conclutions:1. the statistics of SAS image is K distribution,its shape parameter is proportional to the number of the scatters or the patches within the resolution unit,proportional to the beam width of the receive array and inversely proportional to the sending beam width.2. the statistics of contaminated SAS image is K+K mixture distribution,the parameters of the two K distribution are related to the direct and the multipath signals seperately. All the above results will help to isolate the multipath contamination from the direct SAS signal and then to propose some new SAS imaging algorithms which will be able to improve the SAS image quality greatly. The project serves not only the scientific research field but also the local economic construction of Yunnan Province because the relevent technique can be widely used in underwater archaeology, terrain mapping and engineering etc.

英文关键词： Underwater;Multipath;Synthetic Aperture Sonar(SAS);Heavy-tailed;Statistics