导　　师： 李月

学科专业： 081002

授予学位： 硕士

作　　者： ;

机构地区： 吉林大学

摘　　要： 在一些应用领域,混沌信号以噪声的形式存在,此时人们通常对在混沌噪声中信号的检测和提取问题感兴趣,这类信号处理在如海洋杂波中信号检测,混沌保密通信,语音处理等问题中应用很广。文中介绍了现有的几种混沌背景中信号提取方法,并简单作出分析。本文系统分析了混沌吸引子的几何结构特性以及受到其它干扰时其几何结构所发生的变化,混沌具有确定性,具有特殊的几何结构,是奇怪吸引子,这一点同普通噪声不同,也与其它确定性信号不同。在此理论和前人工作的基础上提出了基于余弦变换的相空间投影方法和基于主分量分析的局部相空间投影方法,以实现较低信噪比条件下混沌和信号的分离。另外,在基于离散余弦变换的相空间投影法中,优化近邻点的选取,以提高提取的精度。本文以Lorenz混沌系统作为混沌背景信号,以正弦信号作为目标信号,对上述两种方法进行了一系列仿真实验,并对实验结果进行了分析。 The chaos theory is one of the most important achievements in the field of the non-linear science. Along with the theory of relativity, quantum mechanics, the chaos theory is one of the three major twentieth century revolution in physics. The emergence of chaos theory provides new challenges and opportunities to signal processing. The chaos is a complex behavior showned by nonlinear deterministic dynamical systems. It provides a powerful concept, so that people can use the easy power system to explain the very irregular exercises caused by the nature of the performance of certain physical phenomena. One direction of Chaos engineering research is based on chaos theory. Chaotic signal processing is to solve the problem of the separation of the chaotic signal /(noise/) and useful signal. In accordance with the different purpose of the separation, it can be divided into two situations. A situation wish to get more pure chaotic signal, which is the issue of noise reduction. Another situation is extract useful signal from the chaos' background, which is the signal extraction problem. When infront of with different situations, these two issues are different. This article focuses on the signal extraction from the chaotic background, especially in the direction of weak signal extraction. Meanwhile, there is no priori knowledge beside the observations time series. This is a typical problem blind source separation. Researching on blind source separation problem has two main purpuses. First blind source separation problem is one important theoretical issues of chaotic signal processing. It has not only the important theoretical significance, but also great actually value. For example,target signal extracted from sea clutter/(which has been proved to be chaotic/), fetal electrocardiogram extracted from matrix in biomedicine, weak signal extracted from visual evoked potential and resisting chaotic interference all belong to signal extraction from chaotic background.On the other hand,signal extraction blindly from chaotic

关 键 词： 混沌背景 相空间重构 优化近邻点 局部投影 信号提取

领　　域： [电子电信] [电子电信]