基于UKF的GNSS高动态载波跟踪环路设计与性能分析

摘要

对高动态环境下的全球卫星导航系统(GNSS)载波信号跟踪方法进行了研究,提出了一种基于无迹卡尔曼滤波器(UKF)的开环载波跟踪方法.此方法采用四维相位估计模型提高跟踪精度,同时对估计值进行开环补偿以减少滤波器估计滞后性,并能够消除BPSK相位翻转对UKF造成的不良影响.通过模拟高动态运动下的GPS接收信号,从跟踪精度、失锁概率和误码概率三个方面,与基于UKF的闭环载波跟踪结构的环路性能进行了比较.结果表明,基于UKF的开环跟踪方法可显著提高相位跟踪精度,误差仅为基于UKF的闭环结构的50％,并具有更强的收敛性,可以降低环路失锁率,同时误码率提升1.5dB.%The carrier tracking loop of global navigation satellites system ( GNSS) receiver in high dynamic conditions was researched, and an open-loop carrier tracking method based on unscented Kalman filter (UKF) was proposed. This new method adopts the four-dimensionality UKF phase estimator to increase the tracking accuracy, and compensates the estimated values to reduce the hysteresis of the filter. Besides, it can eliminate the harmful affect of BPSK modulation on the UKF. The performance of this open loop was compared with the closed loop in the aspects of tracking errors, unlocking probability and bit error rate (BER) by simulating the received signal of GPS in high dynamic movement, and the results show that this open-loop compensation method can remarkably improve the tracking precision ( decreasing the tracking errors by 50% ) , the convergence of UKF (leading to lower probability loss of lock), and the BER performance (improved by 1.5dB).