基于稀疏分解的非合作猝发信号解调技术研究

1、杭州电子科技大学硕士学位论文基于稀疏分解的非合作猝发信号解调技术研究姓名：方耀申请学位级别：硕士专业：信号与信息处理指导教师：汪立新20100301杭州电子科技大学硕士学位论文 I摘 要 随着电子信息的发展，军事部门越来越依赖于利用无线电通信对部队进行指挥与部署。现代军事战争己演变为一场对电子资源利用与争夺的战争，敌对双方在信号截获与反截获的斗争将愈演愈烈，各种各样的通信方式不断涌现，随之而来的截获与识别手段也不断提升。无线电通信是以电磁波辐射的形式进行的，具有空间开放性，发送的信号被己方接收的同时，难以避免被敌方侦察到，也无法避免敌方干扰信号的侵入，因此利用一种安全可靠的通信方式进行信息的传递非常重要。而与之相对的，若能发现一种简单高效的信号识别手段也将对现代战争结局产生决定性的影响。在这样的背景下，基于稀疏分解的非合作猝发信号解调技术研究具有重要的应用价值和实际意义。 猝发通信发射机只在极短的时间里工作，其余绝大部分时间里保持静默，可在一定程度上避开敌方的干扰和测向，减少被截获的机会；并大大降低发射机的功率要求，缩小发射机的体积，还能缩短信道的占用时间。相对于普通信号而言，猝发信号

2、的出现时刻是随机的，而且持续时间非常短暂，具有强保密、抗干扰等优点。在非合作接收的情况下，由于缺乏必要的先验信息，对截获的猝发信号如何进行解调成为一个困难的问题。因此猝发信号成为军事通信领域中常用的一种通信信号。 稀疏分解作为一种新兴的信号分解方法，具有很多优良特性，它通过原子分解，可以将信号的频率、幅度、相位等参数反映在稀疏分量中，避开载波同步等环节。在信号处理中稀疏分解有非常广泛的用途，已经应用到信号的压缩编码、信号的识别、信号的时频分布等多个领域。本课题主要研究对象是非合作猝发信号，通过将稀疏分解引入到信号解调中，提出一种实现非合作猝发信号参数估计和解调的全新思路。 文章首先介绍采用猝发信号的通信双方建立对话的过程， 以及非合作方的信号截获措施，阐述了猝发通信的调制解调的基本原理与流程，同时认为现有的解调系统对猝发信号的解调有些力不从心，特别是对非合作状态下截获的猝发信号的解调更是无从下手。随后在比较分析了信号表示领域常用方法的优缺点，以及结合通信信号在一定的变换域上能表现出稀疏性后，提出可以将一种新的信号表示理论稀疏分解应用于猝发信号解调。在接下去的两章中对稀疏分解理论从寻优算

3、法设计和过完备字典构建两个方面展开讨论，提出相应的改进和优化，减少了计算量，降低了运算复杂度，在整体性能上有了一个较大的提升。接着将改进优化后的稀疏分解应用到信号的去噪和参数估计两个领域，并着重对当中的一些关键步骤和重点问题进行详细的分析和探讨。最后对全文涉及到的观点与想法做了相应的仿真，验证了理论研究的可行性与可靠性。 关键词：猝发信号，信号表示，稀疏分解，参数估计，解调 杭州电子科技大学硕士学位论文 IIABSTRACT With the development of electronic information, military departments use radio communication more and more for command and deployment in a war. Modern war turns into a fight on the utilization and scramble of electronic resources. With various communication modes continuously generati

4、ng, opposing sides concentrate on competitions of signal interception and anti-interception. As a result, intercepting and identifying means are also being improved. Radio communication is conducted in the form of electromagnetic radiation with an open space. When our own side received the sending-out signal, it is possible for belligerent to detect the signal at the same time. There is no way to prevent the invasion of enemys jamming signal. So, it is extremely important to use a safe communica

5、tion means for information transmission. In contrast, if we can find a simple and effective means of signal identification, it will play a decisive role in the outcome of modern war. In this background, researches on non-cooperative burst signal demodulation will bring great application value and practical significance. And this kind of demodulation is only based on sparse decomposition. Burst communication transmitter just does a short-time work. During most of the time, it keeps silent. To a c

6、ertain extent, this operating state not only can avoid enemys interference and direction to reduce the interception opportunities, lower the requirement on transmitters power, but also can sharply cut its volume. Besides, it can shorten the occupied time of signal channel. Relative to the normal signal, burst signals presentation time is random and the duration is very short. It possesses strong confidence, anti-interference, and other properties. In the situation of non-cooperative receiving, i

7、t is difficult to demodulate a burst signal, due to the shortage of necessary information. Therefore, the burst signal became one kind of communication signals which commonly used in military information resistance. As a new method in signal decomposition, the signal sparse decomposition has many good features. It reflected frequency, amplitude and phase on the sparse components through the atomic decomposition and avoided the carrier synchronization. It has been widely applied in signal process

8、ing, such as signal compression coding, signal identification, signal time-frequency distribution research and so on. The non-cooperative burst communication signal is the principal research object in this paper; we take the sparse decomposition theory into signal demodulation process, and propose a new paradigm in non-cooperative burst signal parameter estimation and demodulation. First of all, we introduced the establishment process between two communication sides using 杭州电子科技大学硕士学位论文 IIIburst

9、 signal, also introduced some interception measures of non-cooperative signal. Simultaneously, we explained the basic principles and flows of modulation and demodulation with burst communication signal, then pointed out that the present demodulation systems is powerless on burst signal demodulation, especially on demodulation of non-cooperative receivings. Compared with advantages and disadvantages of the commonly used methods in signal indication field, and also considering the sparse characteristic on certain transformation territory performed by communication signal, we suggest that a brand-new signal theory can be applied into burst signal demodulation. In the next two chapters, we begin with the sparse decomposition theory discussion from optimization algorithm for designing and establishment of over-complete dictionaries, and made corresponding improvement and optimization. This can reduce computation and operation complexity, and obtain a great improvement on the whole

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