GPS软件接收的关键技术

The key technology of GPS software receiver

目的讨论GPS软件接收机中核心模块的实现算法,重点研究捕获算法。方法在捕获模块中采用基于DFT的频域快速相乘相关算法,通过相位关系计算出精确的载波频率,同时优化计算;跟踪算法采用软件锁相环路(PLL)实现。结果用MATLAB仿真实现了捕获跟踪过程,相关点峰值高于预设的阈值,成功捕获了GPS信息。结论所采用的基于DFT的频域相关优化算法不仅实现了准确的相关捕获,且可适应实时性需要,为软件接收机的设计实现提供了一种有效的算法。

Aim To discuss the key implementation algorithms for GPS software receiver.Emphasize on acquisition module.Methods The correlation algorithm based on DFT which can fast multiply in frequency field is used in the acquisition module.Then a more accurate carrier frequency is calculated by a phase relationship.Optimization algorithm is used in the calculation.As for tracking module,the software phase lock loop（PLL） is used.Results A processing of acquisition and tracking was simulated by MATLAB.The peak value of correlation point was higher than the presumed threshold.The GPS information was acquired successfully.Conclusion The optimized frequency field correlation algorithm based on DFT not only has realized acquisition correctly,but also can adapt to real-time needs.This algorithm can be used to software GPS receiver effectively.