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题名	GPS软件接收机原理和实现
作者	高洁雯
学位类别	硕士
答辩日期	2007-06
授予单位	中国科学院测量与地球物理研究所
授予地点	武汉
导师	柳林涛
关键词	软件接收机 信号捕获 曲线拟合 信号跟踪 信号模拟 导航信息
学位专业	大地测量学与测量工程
中文摘要	GPS全球定位系统目前是应用最广泛的全球精密导航、指挥和调度系统。对于终端用户来说，GPS系统的核心部分则是GPS接收机，其主要任务是：捕获到待测卫星的信号，并跟踪这些卫星的运行，对接收的GPS信号进行变换、放大和处理，以便测量出GPS信号传播时间，解译导航电文，实时地计算出测站的三维位置，甚至三维速度和时间。本论文旨在开发直接运用于用户端的GPS软件接收机，即通过软件算法来完成各种功能，使之具有更好的可扩展性、应用环境适应性、低成本高灵活性、方便小型化等多种特点，这就打破了长期以来设备的通信功能实现仅仅依赖于硬件的发展格局。论文着重研究并实现了软件形式的接收机各个主要部分的功能，主体结构包括GPS信号的仿真模拟、软件接收机捕获模块的实现、软件接收机跟踪模块的实现、数据解码以及导航信息的提取四个部分。在捕获模块的实现中，通过对比传统的捕获方法包括时域滑动相关和频域循环相关两种方法，求得捕获环节的重要参数C/A码初始位置和初始载波频率，同时比较了两种方法各自的优缺点以及针对不同信噪比的信号，如何选取相对更加适合的方法进行捕获；同时在此基础上，首次尝试采用一种降低频率搜索步长并结合二次曲线拟合的方法以获取高精度的载波频率，进而更好地提高整个捕获准确性以及精度，优化了捕获环节。在跟踪模块的实现中，利用捕获的结果进一步跟踪信号的变化情况，主要采用两个环路同时对信号进行跟踪，包括载波环路和C/A码跟踪环路，其中载波环路采用的是COSTAS环，以及时的更新信号载波频率的变化。并在此基础上深入分析了环路中各鉴相器的选择和环路实施过程中，多个门限参数的设置情况。最终成功地对多颗卫星信号实现了一段时间的持续跟踪。而GPS信号的仿真模拟则可以为整个软件接收机提供可以再现，可控的测试环境，以证明以软件的形式对GPS信号进行处理的可行性和准确性。数据解码和导航信息的提取则是为最终计算测站三维位置，卫星距离等结果所做的一些 准备工作。论文对软件接收机多个主要功能模块的设计以及实现还是基于实验阶段，距离真正意义上可供用户使用的软件接收机还具有一定的距离，但是其中所作的工作、模块功能的优化和所得出的一系列结论对于实现真正可以投放市场的软件接收机都具有一定的借鉴意义
英文摘要	So far, the GPS system has been considered as the most wildly used precision navigation system. For the End-users, the core of the whole system is the GPS receiver. The receiver is used to capture and track the signal coming from the satellite, and then do the signal processing and amplifying to calculate the navigation data and time of transmission. At last, the three-dimensional position, the time, and even the velocity can be acquired. This thesis’s target is to develop GPS software receiver which can be used by the End-users, make it functional through arithmetic. And this kind of receiver will be more compatible, adaptive, flexible, inexpensive and convenient. It also break the structure of hardware reliant. This thesis is focus on the realization of four primary parts of GPS software receiver, including the simulation module of GPS signal, the acquisition module of GPS signal, the tracking module of GPS signal, the decoding module of navigation data. In the realization of the acquisition module, two conventional methods are carried out, these two methods are serial search method based on slide correlation of time domain and parallel search method based on the frequency domain. Then do the comparison of the two to choose a better way for different SNR signal. The acquisition module gets two important parameters, the initial carrier frequency and the initial position of C/A code. On the basis of what have got, the author tried a new way of conic fit and reduce the frequency resolution to get more precise carrier frequency to make the acquisition module more accurate and precise. In the realization of the tracking module, two circuits are carried out to track the signal, these two circuits are carrier tracking loop and C/A code tracking loop, the carrier loop uses COSTAS loop to make sure the carrier frequency can be updated on time. And more work is done on how to choose the discriminator and the setting of some thresholds on the implementation of the whole tracking loop. At last, the real signal can be tracked through the loop successfully. The goal for the realization of the simulation module is to provide some circumstance, under which the GPS software receiver can be tested and controlled, and also the feasibility and accuracy of the GPS signal processing can be testified. And the decoding module of navigation data is the preparation for the final calculation of the three-dimensional position. The design and the implementation of the whole GPS software receiver is carried out tentatively, so far, it is not a real GPS receiver that can be sold as a product in the market, but all the work which has done in this paper, and all the conclusions which this paper give out is very significant, and can be used for reference in the later research
语种	中文
公开日期	2013-01-25
内容类型	学位论文
源URL	[http://ir.whigg.ac.cn//handle/342008/3704]
专题	测量与地球物理研究所_学生论文_学位论文
推荐引用方式 GB/T 7714	高洁雯. GPS软件接收机原理和实现[D]. 武汉. 中国科学院测量与地球物理研究所. 2007.

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