毕业设计（论文）
题 目：GPS C/A码的捕获仿真研究
目录
摘要 ............................................................................................................................................ 1 Abstract ....................................................................................................................................... 2 1
绪论 ..................................................................................................................................... 3 1.1 研究背景及应用现况 .................................................................................................. 3
1.1.1 GPS的发展史及系统概述 ................................................................................. 3 1.1.2 GPS定位技术应用现况 ..................................................................................... 3 1.2 各国导航定位系统研究现状 ...................................................................................... 4 1.3 课题研究内容及意义 .................................................................................................. 4 1.4 论文章节安排 .............................................................................................................. 5 2
GPS导航定位信号及定位原理 ......................................................................................... 6 2.1 GPS系统结构 ............................................................................................................... 6 2.2 GPS信号结构 ............................................................................................................... 7
2.2.1 GPS信号产生 ..................................................................................................... 7 2.2.2 GPS卫星的导航电文 ......................................................................................... 9 2.2.3 C/A码及其产生 ............................................................................................... 10 2.3 GPS系统定位基本原理 ............................................................................................. 13 3
GPS卫星信号的捕获 ....................................................................................................... 14 3.1 GPS信号接收机 ......................................................................................................... 14 3.2 GPS卫星信号捕获的考虑 ......................................................................................... 14
3.2.1 GPS卫星信号的多普勒效应 ........................................................................... 14 3.2.2 捕获的最大电文长度 ...................................................................................... 16 3.2.3 捕获的频率步长 .............................................................................................. 16
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3.3 GPS卫星信号的捕获方法 ......................................................................................... 16
3.3.1 传统捕获方法 .................................................................................................. 17 3.3.2 循环相关捕获方法 .......................................................................................... 19 3.3.3 延迟与累积捕获方法 ...................................................................................... 21 3.4 捕获不确定性的相关处理 ........................................................................................ 21 4
C/A码捕获的仿真实现 ................................................................................................... 24 4.1 MATLAB简介 ............................................................................................................ 24 4.2 传统捕获及循环相关捕获方法仿真 ........................................................................ 24
4.2.1 单个采样C/A码的产生 ................................................................................. 24 4.2.2 生成C/A码并数字化 ..................................................................................... 25 4.2.3 执行捕获 .......................................................................................................... 26 4.3 仿真结果及分析 ........................................................................................................ 27 结论 .......................................................................................................................................... 30 谢辞 .......................................................................................................... 错误！未定义书签。 参考文献 .................................................................................................................................. 31
GPS C/A码的捕获仿真研究
摘要：全球定位系统（GPS）是由美国开发的卫星导航定位系统，广泛应用于军事、国防建设以及交通导航等领域，
通过C/A码捕获的仿真研究可以为GPS信号的进一步跟踪和解调提供基础。本文主要研究了传统捕获和循环相关捕获方法，介绍了延迟与累积捕获手段，运用MATLAB仿真软件来确定C/A码的起始点和载波频率。首先，学习了GPS信号基本结构及C/A码的产生原理，阐述了GPS定位基本原理；然后学习了三种捕获方法的基本工作原理，论述了捕获中的不确定性及处理方法，研究分析了C/A码捕获的具体过程；最后通过MATLAB软件进行仿真实现。仿真过程中，主要运用了循环相关捕获方法，并且在仿真中消除了捕获过程中的不确定性，找到C/A码的起始点以及它的载波频率，最终完成了对GPS C/A码的完整捕获。
关键词：GPS系统；C/A码；捕获；MATLAB仿真
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Research on GPS C/A Code Acquisition Simulation
Abstract：Global positioning system (GPS) is a satellite navigation and positioning system developed by the United States.
The technology is widely used in military, national defense construction, traffic navigation and so on. The simulation of C/A code acquisition can provide the foundation for further tracking and demodulating GPS signals. This undergraduate dissertation mainly studies the traditional acquisition method and cycle-related acquisition method, introduces the delay and cumulative acquisition method, and determines the starting point and carrier frequency of C/A code based on MATLAB simulation. Firstly, the basic structure of GPS signal and the principle of C/A code generation are studied, and the basic principle of GPS positioning is expounded; Then the basic working principles of the three acquisition methods are studied, the uncertainties in the acquisition and the treatment are discussed, and the specific process of C/A code acquisition is analyzed; Finally, the study is simulated based on MATLAB. In the simulation process, the cycle-related acquisition method is mainly used, and the uncertainties of the acquisition process are eliminated in the simulation. Through the simulation, the starting point and carrier frequency of the C/A code are found and the complete acquisition of the C/A code is realized.
Key words：GPS system；C/A code；acquisition；MATLAB simulation
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