【作者】 简波；

【导师】 张爱丽；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2011， 硕士

【摘要】 近些年来,扩频通信在各个领域都得到了快速的发展,它不仅在军事通信中的地位显得越来越重要,在民用通信中也得到了越来越广泛的重视。作为扩频通信体制中的一种重要类型,跳频(Frequency Hopping)通信以其出色的抗干扰、抗衰落能力和高保密性能,在扩频技术中脱颖而出。为提高数据传输的可靠性,需要首先解决的问题是选择一种具有较高通信效率的数字调制方式,这对于提高系统的抗干扰性能和频带利用率都很重要。因此,本文将对不同调制方式下的跳频通信系统的抗干扰性能进行研究。另一方面,跳频同步一直以来就是跳频技术研究的重点问题,是跳频通信的关键技术,为了更好的实现同步信息的捕获和跟踪,因此需要精心地设计同步方案。本文首先分析了扩频通信系统的基本原理,并对其特点、结构进行了描述,然后通过描述跳频通信系统的基本结构和概念,给出了其数学模型,并对它的通信原理进行了理论分析,接着介绍了跳频通信的一些关键技术和技术指标,重点描述了跳频同步的基本理论、同步方法和同步过程,并对调制方案的选取进行了简要的分析。其次,基于Matlab/Simulink建立三种不同调制方式下的跳频系统模型(包括二进制频移键控BFSK,二进制相移键控BPSK和高斯最小移频键控GMSK),分别搭建了宽带阻塞式干扰模块、多频连续波干扰模块、部分频带干扰模块和频率跟踪式干扰模块,并通过仿真,分析并比较在三种调制方式下,跳频系统对以上各种干扰的抗干扰性能,为现代跳频通信技术中选用合适的调制解调方式提供一定的理论参考。最后,对一种TOD+同步字头法的同步方案进行了祥细的描述分析,通过对该方案进行数值仿真,详细分析了其同步性能,然后基于差分跳频的基本原理,给出一种同步改进方案。该方案将差分跳频机制引入跳频同步过程,通过误跳纠正的频率序列检测算法来检测同步信息,并对该方案算法进行仿真分析,结果表明：在进行了误跳纠正的情况下,系统在较低信噪比时仍然可以获得较高的同步捕获概率,且其同步捕获概率远远高于无误跳纠正时的捕获概率；相比于TOD+同步字头法的同步方案,该方案在获得较短同步捕获时间的同时也能够得到较高的同步捕获概率,从而为研究跳频同步方案的学者提供了一定的参考。更多还原

【Abstract】 With the rapidly development of SS (spread spectrum) technique, SS communication is not only becoming increasingly important in the military, but also has obtained more and more extensive attention in the civilian communications in recent years. FH (Frequency Hopping) system plays an important part in the SS communication system and has gone in the fore part of the SS techniques because of its excellent anti-jamming, anti-fading capability and high security.In order to guarantee the reliability of data transferring, it is necessary to find an efficient data modulation. It is very important for both enhancing system anti-jamming performances and bandwidth efficiency. Therefore, on one hand, this article is to research the anti-jamming performances under different FH system environments in terms of different data modulations. On the other hand, the FH-synchronization is the key focus of FH technique field, which is also the key technology. For better instant information receiving and tracking, we need to design exquisite instant programs.First of all, This article analyzed the principles of spread spectrum commucication system, and then described its characteristics and structures. Based on the descriptions of FH system structures and definitions, this article set up a mathematical model, followed by its theoretical analysis in terms of its principles, some key technologies and related indicators about FH system. This article focally described the basic theories, instant methods, and related progress of FH system, followed by related simple analysis of modulation programs.Secondly, it builds different FH system models under the different types of way of modulation (including the binary frequency shift keying BFSK, binary phase shift keying BPSK and Gaussian minimum shift keying GMSK) based on Matlab/Simulink in the article. Then it respectively set up the models of Wideband Noise Jamming, Multi-tone Noise Jamming, Partial Band Noise Jamming and Follower Jamming, and then analyzed the different anti-jamming performances under the three different modulation based on the practical tests. Through analyzing the curves comparatively, we can get a theoretical reference for the modern FH communication system when an appropriate modulation and demodulation scheme is needed.At last, this article shared the detail description of the synchronization program based on TOD (Time of Day) and synchronization-head, and analyzed its synchronization efficiencies based on the simulation. Then an improved scheme of FH-synchronization is proposed based on the basic principle of DFH (differential frequency hopping). The scheme introduces DFH mechanism into the process of FH-synchronization and synchronization information can be detected through the frequency sequence detection algorithm which can correct error detection. Then it analyzes the scheme and the simulation of mathematical algorithms has been given, and the results show that:the FH system can still obtain a higher probability of synchronization-acquisition under the lower SNR condition with correcting error detection and the probability is much higher than that without correcting error detection. Compared with the scheme of FH-synchronization which is based on TOD (Time of Day) and synchronization-head, this synchronization scheme can obtain not only a shorter acquisition-time but also a higher probability of synchronization-acquisition, so it provides a reference to the scholars who study the FH-synchronization scheme.更多还原