补偿码多普勒和本地钟偏的GNSS弱信号捕获

摘要

Weak signal acquisition technology is one of the research difficulties of Global Navigation Satellite System(GNSS).The conventional weak signal acquisition methods only consider the influence of code Doppler while ignoring the impact of local clock skew,and in the process of code Doppler compensation,local code sequences needs to be updated frequently,which increases computation complexity significantly.To address these problems,after an impact analysis of code Doppler and local clock skew on weak signal acquisition,this paper proposed a new method which compensates the code Doppler and local clock skew simultaneously.In the new method,code Doppler is compensated in the procedure of down-sampling,which avoids frequent update of local codes ; local clock skew is compensated in the process of non-coherent accumulation producing a performance improvement of acquisition.Test results show that the new method not only bring about a much lower computation complexity but also achieves a higher sensitivity than conventional methods.%弱信号捕获是全球导航卫星系统(GNSS)领域的研究难点之一.已有的弱信号捕获方法,仅考虑了码多普勒的影响而忽视了本地钟偏的影响,且在码多普勒补偿过程中需要频繁更新本地码表,导致运算量过大.为解决上述问题,在分析了码多普勒和本地钟偏对弱信号捕获性能影响的基础上,提出一种同时补偿码多普勒和本地钟偏的弱信号捕获新方法.改进方法在降采样环节补偿码多普勒,无须频繁更新本地码表；在非相干累加环节补偿本地钟偏,提高了捕获性能.测试结果表明,与已有方法相比,改进方法不仅显著降低了运算量,还可实现更高的捕获灵敏度.