【作者】 卢亮；

【导师】 李海森；

【作者基本信息】 哈尔滨工程大学 ， 信号与信息处理， 2010， 硕士

【摘要】 随着人们对水下探测需求的增长,传统的二维成像声呐已渐渐不能满足人们的要求,三维成像声呐由于能提供水下目标的三维信息,得到的图像更直观,受到了越来越多关注。而目前常用的水下三维成像方法,需要经过多次多角度重复测量,或者需要较复杂的面阵或声透镜。为此,本文研究一种简化的面阵-L型基阵对水下目标进行三维成像的方法。本文改进了一种基于常规的波束形成技术的三维成像方法。将两条线阵的多波束接收数据,按照一定的顺序一一对应相乘,生成一组新数据,再通过对该数据的处理,提取出目标的三维信息,就可以得到目标的三维图像。同时,还从两个不同角度得到了目标的二维图像,从这两幅图像中,也可以提取出目标的三维信息。多子阵波束Root-MUSIC(MSB-RMU)算法较常规高分辨方位估计方法需要的信噪比条件低,又能使空间分辨力不受阵列孔径的限制。在本文中,利用L型基阵这种特殊的阵列形式,将一维MSB-RMU算法扩展到二维,用于三维成像,还对采用的参数配对方法做了进一步分析,结合成像仿真结果,采用了分组排序的参数配对方法。另外,还采用了一种结合了MSB-RMU算法与二维MUSIC算法的参数自动配对的算法。最后,通过建立的仿真成像场景,对上述几种三维成像方法的成像效果进行了对比分析。采用二维MSB-RMU算法的成像效果要明显好于前两种方法。其中,对强度不相等的信源来说,两种采用高分辨技术的算法的成像效果相似,不过,参数自动配对的DOA估计方法对等强度信源同样有效,而二维MSB-RMU算法则会失效。更多还原

【Abstract】 As the conventional 2-D imaging sonar can not fully meet the demands for underwater detection anymore, the sonar system that can provide real-time 3-D images underwater become more and more important. But the real-time 3-D imaging sonar usually depends on 2-D planar array or acoustic lens technology, which are much more complex and expensive than linear array. In this paper, some new 3-D imaging methods that depend on an L shaped array are proposed.A new method that makes use of conventional beam-forming technology is proposed. Its basic principle is multiplying the beam-forming data received from one of the linear array and the beam-forming data received from another linear array together to forming a group of new data, and then forming the 3-D imaging of the object region based on this new data. 2-D images can also be drawn at the same time. With the help of 2-D images, the 3-D imaging of the object region can be more complete.MSB-RMU algorithm is a high resolution DOA estimation algorithm with less SNR requirements than conventional ones. In this paper, 1-D MSB-RMU algorithm develops into 2-D MSB-RMU algorithm by using L shaped array. It can be used for 3-D imaging after parameter matching. Two parameter matching methods are applied. They both depend on the estimation of the strength of target and have some differences in the procedure of matching. Then a new method that combines 1-D MSB-RMU algorithm with 2-D MUSIC algorithm is mentioned too. There is no need to use parameter matching method in this new algorithm. And it can be used for equal-power targets estimation.At last, a simulated imaging model is built and the methods mentioned before are applied. The results of algorithms that use high resolution DOA estimation technology turn out to be much better than the others. The two high resolution algorithms have the same performance to the targets of different strength. But 2-D MSB-RMU algorithm will fail if the targets are have same strength. And this will not happen to the other algorithm.更多还原