MATLAB直扩MSK系统的码同步技术研究
通过对各种文献的了解，简单的介绍了直扩MSK信号系统的结构并对各个部分功能进行了简单分析介绍。给出了一般该信号的调制方法，利用MATLAB进行仿真检验其正确性。另外，还通过仿真出该信号的各种特性曲线，进一步来验证信号产生的合理性和有效性。直扩MSK信号的捕获。着重讨论了如何将其相位差初步锁定在正负Tc/2之内，并且介绍了消除大多普勒频偏的方法。直扩MSK信号的跟踪。介绍了如何实现精确同步的方法。
关键字 扩频 MSK 捕获 跟踪 MATLAB
毕业论文设计说明书外文摘要
Title Research on code synchronization technology for DS- MSK system
Abstract
This paper combines Spread spectrum communication technology(SSC) and the Minimum frequency Shift Keying signal, discussing direct sequence spread spectrum MSK technology (hereinafter referred to as direct expansion MSK) technology. It has a combination of the two advantages, with all the wide channel bandwidth, the good secrecy characteristics and strong anti-jamming capability, widely used in the field of military and satellite communications. The code synchronization research is necessary for signal dispreading. So, the study of direct expansion MSK system code synchronization technology is of great significance.
This paper derives the baseband expression of MSK signal first, realizing its signal, focusing on the study of the spread spectrum MSK signal code synchronization technology, including coarse synchronization - code capture technology, and fine synchronization - code tracking technology.Code capture technology mainly adopts the matched filtering technique. Threshold Settings bases mainly on Neyman-Pearson signal detection criterion. In this paper, the research also finds that under the large doppler frequency offset, matched filtering correlation peak has a certain impact. Thus, frequency offset estimation based on FFT is adopted. Code synchronization technology uses the digital non-coherent ahead–lay delay phase-locked loop. This paper also discusses the performance of the loop, such as loop jitter, based on the MATLAB simulation.
Keywords spread spectrum MSK capture tracing MATLAB
目 次
1 绪论 1
1.1 课题研究的背景 1
1.2 国内外研究动态 1
1.3 论文的主要工作及章节安排 2
1.4 本章小结 3
2 直扩MSK调制原理 4
2. 1 扩频原理 4
2.2 直扩MSK信号调制原理 5
2.3 直扩MSK信号的产生 8
2.4 本章小结 11
3 直扩MSK的码捕获 12
3.1 直扩MSK接收机 12
3.2 匹配滤波器原理 12
3.3 基于奈曼-皮尔逊准则的门限判决 14
3.4 大多普勒频谱下的码捕获 16
3.5 本章小结 19
4 码跟踪技术的研究 20