基于改进锁频锁相的高动态同步算法

摘要

针对卫星定位导航系统多谱勒频移大的特点,根据设计的实际系统推导出锁频锁相算法的理论表达式.对叉积算法得到的结果利用改进的平滑算法进行处理,降低了噪声方差.与此同时使锁频环和锁相环同时工作,加快了更新时间.对上述改进算法进行单片FPGA实现,采用NiosⅡ代替传统的DSP对算法的锁频锁相部分进行实现,增加了系统的稳定性和可靠性.通过实验验证,提出的改进算法解决了环路跟踪精度和动态性能不能兼顾的矛盾,各项技术指标达到或超过系统设计的要求.%Aiming at the characteristics of navigation satellite system,theoretical expressions of frequency-locked and phase-locked algorithm are gained according to practical system.The results of AFC algorithm are processed using modified smoothed algorithm,and its covariance is decreased.Simultaneously,Frequency-locked loop and cestas loop work synchronously,which shorten the update time of them.Above algorithm is realized using single FPGA,frequency-locked loop and phase-locked loop are imple-mented by NiosⅡ replacing conventional DSP,and these enhance stability and reliability of system.Some tests prove that contra-diction between tracking precision and dynamic performance is resolved basically.All required technical guideline of the system are achieved or exceeded.