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为了提高北斗用户接收机的双向授时精度,通过对北斗导航系统双向授时方法以及接收机中温补晶振误差模型的研究,提出了用闭环自适应卡尔曼滤波算法对观测值进行相位和频率的估计,并对下一采样时刻的钟差和钟差变化率进行预测的方法。介绍了Kalman滤波器噪声方差阵的自适应估计算法,设计了自适应Kalman滤波器。将北斗用户接收机对卫星的双向授时数据进行采集仿真。从仿真数据得出:使用自适应Kalman滤波算法可以大大提高北斗接收机中晶振的钟差和钟差变化率的估计精度,且随着估计间隔的增长,其估计精度会更加精确。同时用于评价晶振频率稳定度的艾仑方差也会被稳定在10-15数量级上。最后对该结论产生的原因进行了分析。
In order to improve the bidirectional timing accuracy of the Beidou user receiver, the closed-loop adaptive Kalman filter algorithm is proposed to estimate the phase and frequency of the observed value by studying the bidirectional timing method of the BeiDou navigation system and the temperature compensation crystal model of the receiver. And the next sampling moment of clock error and clock rate of change forecasting method. The adaptive estimation algorithm of Kalman filter noise variance matrix is introduced and an adaptive Kalman filter is designed. Beidou user receiver on the satellite two-way timing data acquisition and simulation. The simulation results show that using the adaptive Kalman filtering algorithm can greatly improve the accuracy of the crystal oscillator clock and the clock rate of change in the Beidou receiver, and the estimation accuracy will be more accurate as the estimation interval increases. The Allan variance, which is also used to evaluate the stability of the crystal frequency, is also stable on the order of 10-15. Finally, the reasons for the conclusion are analyzed.