近赤道地区强电离层闪烁情况下基于软件接收机的GPS载波相位特性分析

论文总字数：29065字

摘 要

全球定位系统（GPS）具有能够克服恶劣天气、持续工作时间长、定位精度较高等特点，在导航和用户定位方面发挥着举足轻重的作用。目前GPS系统已经广泛应用于我们的日常生活，比如：测绘、车辆和行人导航，智能手机以及很多其他的领域。GPS与我们的生活息息相关，GPS接收机的性能更是极大的影响到了定位的精确度和可靠度。近年来，GPS软件接收机凭借着其低成本、灵活易改的特点获得了更大发展前景和研究价值。本文重点对L1波段的数据进行了捕获跟踪和定位原理，并研究电离层闪烁对软件接收机性能的影响。

首先，本文介绍了GPS系统目前的发展状态和基本的构成。然后阐述了GPS卫星发射信号的构成的相关理论知识。结合基于MATLAB的软件接收机研究信号捕获、追踪和定位的过程，分析软件捕获追踪的仿真结果。此外本文依据软件接收机捕获追踪的结果和得到的图像，研究电离层闪烁对接收机的性能影响。通过研究发现，电离层闪烁会导致一系列的GPS软件接收机的的I/Q支路的跟踪变化、信号载噪比的衰落、幅度衰落和相位周跳等。电离层闪烁对GPS应用的精确度和准确度造成了相当大的威胁。

本实验过程舍弃了传统的硬件接收系统，采用基于MATLAB的软件接收机，大大提高了修改参数，提高精度的便捷程度。通过修改对应的参数来改变捕获和追踪的时间和精度，节约了成本和扩大了适用范围。基于MATLAB的运行环境下，使得软件接收机的维护和修改更为方便，运行速度也相应提高。

关键词：GPS，捕获，追踪，电离层闪烁

ANALYSIS OF CHARACTERISTICS OF GPS CARRIER PHASE BASED ON SORFWARE RECEIVER WHICH IS EFFECTED BY THE IONOSPHERIC SCINTILLATION NEAR THE EQUATORIAL REGION

Abstract

The Global Positioning System (GPS) has the characteristics of wide coverage. With the ability of working on bad weather makes it plays a significant role in navigation. Nowadays, GPS systems have been applied in many fields, including mapping, vehicle and pedestrian navigation, smart phones and many other areas. GPS receiver will affect the navigation both in the accuracy and reliability. Compared with the traditional hardware receiver, GPS software receiver has more development space and research value, because the software receiver is more flexible and much easier to change its settings. This thesis focuses acquisition，tracking，positioning on the data of L1 carrier. Secondly, this thesis introduces the basic principle of tracking and phase measurement, and tries to study the influence of ionospheric scintillation on the performance of software receiver.

Firstly, the thesis introduces the development of GPS system. What’s more, it also introduces the three parts of this system. Then, the theoretical knowledge of the carrier, PN code and data code of the GPS satellite transmitting signal is described. Combining with the process of signal acquisition, tracking and positioning of the software receiver which is based on MATLAB, the simulation results of acquisition and tracking are analyzed. In addition, based on the results obtained from the 1 hour acquisition of software receiver and the obtained simulation images, the influence of ionospheric scintillation on the receiver performance is studied. Through the study found that the ionospheric scintillation can lead to a series of GPS pseudo range measurement delay and GPS carrier phase measurement phase advance. The ionospheric scintillation caused a considerable threat to the accuracy and accuracy of the GPS application.

In experiment, we don’t rely on the traditional hardware receiving system. Instead, we adopt the software receiver which is based on MATLAB. Using the software receiver can greatly improve the accuracy of the system. It will be much easier to change the time and precision of acquisition and tracking by changing the corresponding parameters, which helps save the cost and expanding the scope of application. Fast running speed in MATLAB environment is helpful to improve the speed and precision of GPS positioning.

KEY WORDS：GPS, Acquisition , Tracking, Ionospheric Scintillation

目 录

摘要 Ⅰ

Abstract Ⅱ

第一章 绪论 1

1.1引言 1

1.2 GPS系统的发展现状 1

1.3电离层闪烁的研究现状 1

1.4本文研究目的和主要研究内容 2

第二章 GPS的组成和定位原理 3

2.1 GPS的基本组成 3

2.2 GPS信号 3

2.2.1载波 3

2.2.2伪码 4

2.2.3数据码 5

2.3 GPS的定位原理 5

2.4 本章小结 5

第三章 信号的捕获 6

3.1参数介绍 6

3.1.1信噪比和载噪比 6

3.1.2噪声带宽 6

3.2信号捕获原理 6

3.3并行码相位搜索捕获算法 7

3.4信号捕获的图像 9

3.5本章小结 8

第四章 信号的跟踪 9

4.1锁相环 9

4.2码环 9

4.2.1码环的工作原理 11

4.2.2码环工作流程 12

4.3本章小结 13

第五章 电离层闪烁 15

5.1电离层闪烁简介 15

5.2电离层闪烁指数 15

5.2.1幅度闪烁指标 15

5.2.2相位闪烁指标 16

5.3电离层闪烁对GPS接收机的影响 16

5.3.1电离层闪烁对载波相位的影响 16

5.3.2电离层闪烁对跟踪的影响 17

5.3.3电离层闪烁对定位精度的影响 17

5.4本章小结 17

第六章 结合图像分析电离层闪烁对GPS接收机的影响 18

6.1实验概述 18

6.2对卫星捕获的影响 18

6.3对载波相位的影响 19

6.4对I/Q支路跟踪值的影响 19

6.5对载噪比的影响 20

6.6对信号强度的影响 21

6.7本章小结 22

总结 23

致谢 24

参考文献（References） 25

1. 绪 论

1.1 引言

随着全球经济的发展，全球定位导航系统的发展也相当迅速。小到手机导航、车载导航，大到测绘定位、军事战役等无一不涉及到GPS的应用。为了满足民用、军用以及现代化应用对定位的不同精度的要求，现阶段的GPS卫星上有三个频率，分别是L波段的L1、L2和L5，用以发射卫星信号，以满足民用、军用、商用等不同方面的需求^[1]。本文主要针对民用波段L1进行讨论和研究。

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