基于MATLAB的GPS信号的仿真

摘要

扩频通信是近几年来迅速发展起来的一种通信技术。在早期研究这种技术的主要目的是为提高军事通信的保密和抗干扰性能，因此这种技术的开发和应用一直是处于保密状态。扩频技术在军事应用上的最成功范例可以以美国和俄国的全球定位系统（GPS和GLONASS）为代表；在民用上GPS和GLONASS也都得到了广泛的应用，这些系统的基础就是扩频技术。

全球定位系统（GPS）用于对全球的民用及军用飞机、舰船、人员、车辆等提供实时导航定位服务。GPS系统采用典型的CDMA体制，这种扩频调制信号具有低截获概率特性。该系统主要利用直接序列扩频调制技术，采用的伪码有C/A码和P(Y)码两种。

本文讲述的是直接序列扩频通信技术在全球定位系统（GPS）中的应用。主要介绍扩频通信中的伪码仿真，简要论述M序列和伪随机噪声码（P码和C/A码）及其产生，并使用MATLAB7.0仿真M序列、P码和C/A码的编码过程和仿真结果，介绍直扩频技术伪码的相关知识，重点介绍P码。

关键字：全球定位系统；直接扩频通信；伪码仿真

Abstract

Spread spectrum communication is a communications technology developed rapidly in recent years. In early studies the main purpose of this technology is to improve the military communications confidential and anti-jamming performance, therefore the development and application of this technology is always in secret state. Spread spectrum technology in the most successful military application examples are the United States and Russia could the global positioning system (GPS and GLONASS) for representative; In civil GPS and GLONASS also have been widely used，which foundation of system is the spread spectrum technology.

Global positioning system (GPS) is used to provide real-time navigation and positioning services for global civil and military aircraft, ships, personnel, vehicles and so on. GPS system adopts the typical CDMA system, which kind of spread spectrummodulation signals have low intercept probability characteristic. This system mainly used the direct sequence spread spectrum modulation technology, using the PRN code including C/A code, P codes and Y codes.

This article tells the direct sequence spread spectrum communication technology applied in global positioning system (GPS) .The article mainly introduces the pn code spread spectrum communication simulation, briefly discussing M sequence and pseudo random noise code (P yards and C/A yards) and its produce and use MATLAB7.0 simulate M series, P yards and C/A yards of encoding process and the simulation results, introducing pn code straight spread-spectrum technology knowledge, especially P yards.

Key: GPS; DS-SS;Pn code simulation

目录

引言 (4)

1GPS理论及其特性 (5)

1.1GPS系统概述 (5)

1.2GPS信号构成 (7)

1.2.1M序列 (10)

1.2.2C/A码 (13)

1.2.3P码 (15)

1.3小结 (20)

2MATLAB软件 (21)

2.1MATLAB软件简介 (21)

2.2MATLAB应用概述 (22)

2.2.1 MATLAB功能介绍 (22)

2.2.2 MATLAB使用方法 (24)

3 GPS卫星导航信号算法及其MATLAB仿真 (31)

3.1 C/A码仿真代码及其仿真结果 (31)

3.2 P码的仿真代码及其仿真结果 (34)

3.3 结果分析及其相关性分析 (38)

结论 (39)

致谢 (40)

参考文献 (41)

附录A 英文原文 .................................................................................................. 错误!未定义书签。附录B 中文翻译................................................................................................... 错误!未定义书签。附录C C/A码源代码. (42)

附录D P码源代码 (56)