基于FPGA的GPS基带信号处理的研究与实现

【作者】 宋杰；

【导师】 丁庆生； 黄伟；

【作者基本信息】 电子科技大学 ， 电子与通信工程， 2010， 硕士

【摘要】 GPS全球定位系统是美国国防部为军事目的而建立的卫星导航系统,其主要目的是解决海上、陆地和空中运载工具的导航定位问题。GPS作为新一代卫星导航系统,不仅具有全球、全天候、连续、高精度导航与定位能力,而且具有优良的抗干扰性和保密性。因此,发展全球定位系统是当今导航技术现代化的一个重要标志。本文的研究对象是GPS接收机的重要组成部分——基带信号处理模块,主要由两个部分组成——捕获模块和跟踪模块。在对GPS的系统组成和信号结构进行分析后,给出了设计方案,并结合工程设计的特点,对算法进行优化,得出FPGA的实现方案,最后还进行在板验证。本文的内容主要包括以下几个方面：1)对GPS系统的组成简单的介绍,并对GPS卫星信号的结构进行详细介绍,包括载波信号、伪随机码的产生和导航电文的详细内容。2)在GPS信号的捕获方面,比较传统的串行捕获和并行捕获的优缺点,在资源和性能上取合理的折中,选择串并结合的混合并行捕获方案,从而在加快信号的捕获速度和提高捕获性能的同时还减少了硬件资源的消耗。3)在C/A码的跟踪部分,本文采用的是非相干延迟锁定环。输入的中频信号经去载波处理后,分别与本地码的超前、滞后相位序列相乘,将相乘的结果进行积分累加,经过鉴相算法处理后,再将得到码相位和当前的载波频率送到载波跟踪环路。4)载波跟踪环,本文采用的是Costas环。同码跟踪环耦合形成跟踪模块。本文的创新点是使用FPGA对整个GPS信号的捕获及C/A码的跟踪进行工程化设计,使其在资源和性能上做到合理的平衡。更多还原

【Abstract】 Global Positioning System(GPS) is a satellite navigation system established to solve the navigating and positioning problems on land or sea and in the air. As a new generation of satellite navigation system, it not only has global, round - the - clock, continuous, high - precision navigating and positioning functions, but also possesses excellent interference immunity and confidentiality. Therefore, the development of GPS navigation technology has become ever more important in the advancement of navigation industry.The core parts of GPS receiver baseband signal process module - signal acquisition module, tracking module, were investigated in this paper. On the GPS system composition and structure analysis, combining the characteristics of engineering design optimization algorithm is presented, and the implementation scheme, finally implemented on the board.The contents of this paper include the following aspects:1) The composition of GPS simply introduced, and the structure of GPS satellite signal is introduced in detail, including the carrier signal, the generation of PN code and the detailed content of navigation message.2) GPS signals in the capture of the more traditional serial, parallel and capture the advantages and disadvantages of capture, the resources and the performance of the reasonable selection, and eclectic mix of parallel capture scheme, reduce the consumption of hardware resources, accelerate the speed of the signal, and improve the capture capture performance.3) A non - eoherent DLL is used to track the C/A code. The local carriers from carrier tracking loop turn the input signals into the baseband signal, and the baseband signals multiply the two different phase sequence of the local yards, then deal with cumulative results, at last, put the code phase and current carrier frequency into carrier tracking loop.4) Costas loop is used as the carrier tracking loop. With the code tracking loop coupling tracking module. In this paper, a novel approach by using FPGA to capture the GPS signals and track the C/A codes is employed. According to the characteristics of FPGA for engineering design, and implementation in resources and performance is achieved reasonable balance.更多还原