基于FPGA的可重构多模导航基带处理技术研究

发布时间：2018-01-22 21:44

本文关键词： 可重构多模捕获跟踪 FPGA　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：多模定位是指运用多个卫星导航系统进行联合定位,可以极大地增强卫星导航的可用性、连续性、完好性和定位精度,扩大了可用范围,提高了接收机的环境适应能力和抗干扰性。因此,多模导航接收机是未来导航定位发展的必然方向。目前能够实现全球定位的卫星导航系统有GPS、BDS、GLONASS、Galileo四个,能同时兼容四个系统的多模接收机很少。本文设计的多模接收机的基带处理系统为可重构设计,包括捕获模块和跟踪模块,四模间可手动切换,并基于FPGA硬件实现并验证。主要工作有:介绍了多模(GPS、BDS、GLONASS、Galileo)的信号形式及特点。分析了常用的捕获方法和GPS的跟踪方法。研究了多模接收机的捕获、跟踪技术。首先就多模接收机中不同GNSS系统采用的捕获和跟踪技术的异同进行了分析对比。然后对多模捕获所需下变频、多普勒搜索范围、伪码速率和周期进行了详细分析。针对Galileo E1B信号调制有CBOC(6,1,1/11)副载波的特点,采取了BPSK-Like的处理方式,采用二次采样算法首先去除了副载波,使其能和GPS的捕获、跟踪结构兼容。设计了并行码相位搜索的多模捕获方案,尤其根据多模伪码的不同周期和码长,详细分析并设计了共用一个FFT核的方案。通过计算和Matlab仿真确定了跟踪模块的锁相环参数,并对多模跟踪方案进行了设计,使四个系统都能兼容同一种跟踪算法。最后运用Matlab对设计的多模捕获、跟踪结构仿真,验证了设计的可行性和正确性。对前面设计的多模接收机的捕获、跟踪方案用Verilog HDL硬件描述语言实现。分模块对捕获、跟踪各部分进行了设计、综合、优化和仿真,优化代码尽可能使多模捕获、跟踪共用部分最大化,节省制造成本,对不同的部分单独设计实现,以达到重构目的。给出了各个子模块的硬件仿真图和RTL电路图。设计了一个状态机用于实现对捕获、跟踪模块工作状态的控制。最后,对捕获、跟踪模块在FPGA上测试和验证并进行联合调试,各GNSS间能够顺利切换,通过和Matlab仿真结果的对比,捕获模块功能验证正确,成功解调出了各GNSS的导航电文,跟踪模块验证正确,正确实现了多模可重构基带处理。
[Abstract]:Multimode positioning refers to the use of multiple satellite navigation system positioning, can greatly enhance the availability of satellite navigation, continuity, integrity and accuracy, expand the range of available, improved the receiver's ability to adapt to the environment and anti - interference. Therefore, the multimode navigation receiver is the inevitable direction of the future development of the navigation and positioning at present. The satellite navigation system to achieve global positioning are GPS, BDS, GLONASS, Galileo four, compatible with four multimode receiver system. Few multimode receiver baseband processing system designed in this paper for the reconfigurable design, including the capture module and tracking module, manual switching between the four modes, and FPGA hardware implementation based on and verified. The main work is as follows: the multimode (GPS, BDS, GLONASS, Galileo) signal form and characteristics. Analysis of the tracking method and GPS capture method commonly used. On the ground of multimode Capture receiver tracking technology. Firstly, analyzes the similarities and differences in the acquisition and tracking technology with different GNSS system. Then the multi-mode multimode receiver to capture a desired frequency, Doppler search range, PN code rate and cycle are analyzed in detail. According to the Galileo E1B CBOC (6,1,1/11) signal modulation characteristics of vice the carrier, processed by BPSK-Like, using two sampling algorithm first remove the subcarriers, which can capture and track GPS, compatible with the structure is designed. The multi-mode parallel code phase search acquisition schemes, especially according to the different period and the multimode PN code length, and a detailed analysis of the common one the FFT core design. Through calculation and Simulation of Matlab phase-locked and tracking module loop parameters were determined, and the multimode tracking scheme is designed, so that the four systems with a tracking algorithm using the M compatible. Atlab for the design of multimode capture, tracking structure simulation, verified the correctness and feasibility of the design. The design of the multimode receiver capture and tracking scheme using Verilog HDL hardware description language. The module of acquisition, tracking all parts of the design, synthesis, optimization and simulation, optimize the code as much as possible so that the multimode capture, tracking share maximization, save manufacturing cost of different parts of separate design and implementation, to achieve the purpose of reconstruction. Each sub module of the hardware simulation diagram and RTL circuit diagram is given. The design of a state machine is used for capturing, tracking control module working state. Finally, the capture and tracking module in the FPGA test and verification and debugging, can smoothly switch between the GNSS and Matlab, by comparing the simulation results, verify the successful capture module function, to demodulate the navigation power GNSS In this paper, the tracking module is verified correctly and the multimode reconfigurable baseband processing is realized correctly.

【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN967.1;TN791

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