BDS导航信号抗电离层闪烁载波跟踪的自适应卡尔曼滤波算法

Adaptive extended Kalman filter carrier tracking algorithm for BDS signals under ionosphere scintillation conditions

电离层闪烁会引起导航信号幅度和相位的快速衰落,严重影响跟踪环路的精度和稳健性,而相比频率跟踪和伪码跟踪,载波跟踪环路更易受电离层闪烁的影响而失锁。因此,提出一种基于相位锁定指示自适应扩展卡尔曼滤波的北斗导航信号抗电离层闪烁载波跟踪算法,其以同相与正交支路的积分结果估计相位锁定指示值,并采用该指示作为控制参数对不同闪烁场景下扩展卡尔曼滤波的观测向量进行自适应调整,这不仅能够提高跟踪环路的精度和稳健性,而且能够降低扩展卡尔曼滤波发散的概率。实验结果验证了相关分析和所提跟踪算法的有效性。

Ionospheric scintillation is a rapid change in the phase and amplitude of navigation signals,resulting in degraded accuracy and robustness of signal tracking loops. Compared with the frequency tracking loop and delay tracking loop,carrier tracking loop is much weaker,and will lose lock much more continually in scintillation. Therefore,a carrier tracking algorithm for Bei Dou signals scintillation mitigation based on adaptive EKF（ extended Kalman filter） was proposed. The integration of in-phase and quadrature channels was used to estimate the phase lock indicator values which are the control parameter to adjust the measurement vector of EKF adaptively with different scintillation scenarios. Through the adaptive measurement vector,the accuracy and robustness of the tracking can be improved and the probability of filter divergence can be decreased. Experimental results prove the validity of the analysis and the proposed carrier tracking algorithm.