嵌入式实时北斗接收机软件研究与实现

发布时间：2018-03-12 16:16

本文选题：北斗二号　切入点：北斗接收机　出处：《西安电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着用户定位需求的不断扩大,卫星导航系统被广泛的运用到各个领域。为了打破美国和俄罗斯在全球卫星导航领域中的垄断地位,我国自主研发了能够独立运行的北斗卫星导航系统——“北斗二号”。北斗导航系统在导航方式和定位原理等方面与GPS导航系统相类似,但也有自身的独特优势。目前,“北斗二号”正处于不断地建设和完善当中。北斗接收机作为用户终端,是卫星导航系统中的重要组成部分,需要不断改进、发展与优化。因此在现阶段对基于北斗导航的实时接收机进行研究与实现具有非常重要的意义。鉴于北斗接收机需要对信号进行实时性处理,本课题选择了DSP与FPGA作为接收机的硬件平台,主要对接收机的软件部分和信号处理算法进行了研究、设计与实现,最终完成了接收机的定位等任务。论文介绍了国内外卫星导航系统和卫星导航接收机的现状与发展趋势以及北斗接收机的基本原理。设计了北斗接收机的系统框架以及FPGA与DSP的程序模块框架。基于DSP与FPGA的北斗接收机主要以DSP作为核心控制器,通过FPGA对基带信号进行处理;通过DSP对信号进行捕获、跟踪、同步并与FPGA进行数据交换,实时调整FPGA对基带信号的处理;最后通过DSP提取并保存导航电文,利用伪距定位算法计算出定位结果。论文重点对FPGA处理基带信号的各个模块进行了研究、设计与实现,并着重讨论了位同步与帧同步模块的主要设计思想以及导航电文的提取、纠错与校验方法。基带信号处理模块包括时钟模块、载波NCO模块、数字下变频模块、码NCO模块、测距码发生器、码相关运算器与帧同步模块等,这些模块相互连接,从而实现了对基带信号的处理。本文还介绍了基带信号的捕获算法、跟踪算法和伪距定位原理及算法,并根据实际情况选择了合适的算法在DSP平台上进行了实现:基带信号的捕获采用串行捕获方法;信号跟踪使用的码环采用二阶锁相环;载波环采用二阶锁频环辅助三阶锁相环;定位算法采用牛顿迭代法结合最小二乘法。论文的结论部分对该接收机的定位测试结果进行了展示,并和标准GPS的定位结果进行了比较。还对本课题所使用的各个模块和算法进行了总结。并讨论了该接收机需要进行改进和完善的一些后续任务。
[Abstract]:In order to break the monopoly of the United States and Russia in the field of global satellite navigation, satellite navigation system has been widely used in various fields with the increasing demand for positioning by users. Our country has independently developed the Beidou satellite navigation system, "Beidou II", which can operate independently. The Beidou navigation system is similar to the GPS navigation system in terms of navigation mode and positioning principle. But it also has its own unique advantages. At present, Beidou II is under continuous construction and improvement. As a user terminal, Beidou receiver is an important part of the satellite navigation system and needs continuous improvement. Therefore, it is very important to research and implement the real-time receiver based on Beidou navigation at this stage. In this paper, DSP and FPGA are chosen as the hardware platform of the receiver. The software and the signal processing algorithm of the receiver are studied, designed and implemented. The status quo and development trend of satellite navigation system and satellite navigation receiver at home and abroad and the basic principle of Beidou receiver are introduced. The system frame of Beidou receiver is designed. The Beidou receiver based on DSP and FPGA mainly takes DSP as the core controller. The baseband signal is processed by FPGA, the signal is captured, tracked, synchronized and exchanged with FPGA by DSP, and the processing of baseband signal by FPGA is adjusted in real time. Finally, the navigation message is extracted and saved by DSP. Using the pseudo-range localization algorithm to calculate the location results. This paper focuses on the research, design and implementation of each module of FPGA processing baseband signal, and discusses the main design idea of bit synchronization and frame synchronization module and the extraction of navigation message. The baseband signal processing module includes clock module, carrier NCO module, digital down conversion module, code NCO module, ranging code generator, code correlation operator and frame synchronization module. The acquisition algorithm, tracking algorithm, pseudo-range positioning principle and algorithm of baseband signal are also introduced in this paper. According to the actual situation, a suitable algorithm is selected to realize on DSP platform: serial acquisition method for baseband signal, second-order phase-locked loop for signal tracking, second-order frequency locked loop for carrier loop, and third-order phase-locked loop for carrier loop. Newtonian iterative method combined with least square method is used in the localization algorithm. In the conclusion of this paper, the localization test results of the receiver are presented. The results are compared with those of the standard GPS, and the various modules and algorithms used in this paper are summarized, and some further tasks which need to be improved and perfected are discussed.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN965.5

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