基于MATLAB的GPS软件接收机捕获与跟踪算法实现

研究了GPS软件接收机的捕获和跟踪算法,并基于Matlab软件平台和射频前端在PC上实现了GPS软件接收机样机。介绍了GPS软件接收机的结构和数据采集硬件,讨论了GPSC/A码的特性、产生原理以及捕获过程。针对传统的串行搜索算法慢的缺点以及高动态GPS软件接收机的特点,在该样机中实现了快速的基于循环卷积的并行捕获算法,并联合使用超前滞后环和对相位反转不敏感的科斯塔斯锁相环分别对码相位和多普勒频偏进行跟踪,解调得到导航电文。仿真和测试结果表明,使用GPS软件接收机进行信号处理的思想使用户在算法处理和软件升级等方面具有更大的灵活性,可应用于下一代任何全球导航卫星定位系统(GNSS)和空基增强系统(SBAS)接收机的设计。

Realization of acquisition and tracking algorithms for GPS software receiver based on MATLAB

Acquisition and tracking algorithms for GPS software receiver were studied. A prototype of GPS software receiver that runs on PC was developed based on Matlab platform and RF front-end. The structure of GPS software receiver and the data collection hardware were presented. The properties and generation principle and acquisition process of the GPS C/A code were discussed. Since the conventional serial searching algorithm is slow and considering the demand of high dynamic GPS software receiver, a fast parallel tracking algorithm based on cyclic convolution was implemented in the sample receiver, and early-later code tracking loop and Costas phase lock loop were used to track code phase and Doppler frequency shift, respectively. So the navigation data could be demodulated. Simulations and experiments show that the ideas of signal processing using GPS software receiver provide more flexible in algorithms processing and software updating for users, and can be applied to the next generation Global Navigation Satellite System and Space Based Augmentation System receivers design.