基于极大似然估计器的GNSS矢量跟踪算法
收稿日期: 2013-11-11
修回日期: 2014-03-21
网络出版日期: 2014-03-28
基金资助
国家自然科学基金（61201120）；国家“863”计划（2010AA7010213）
GNSS Vector Tracking Algorithm Based on Maximum Likelihood Estimator
Received date: 2013-11-11
Revised date: 2014-03-21
Online published: 2014-03-28
Supported by
National Natural Science Foundation of China (61201120); National High-tech Research and Development Program of China (2010AA7010213)
矢量跟踪是一种将全球导航卫星系统（GNSS）接收机的信号跟踪与导航解算融为一体的跟踪算法。传统的基于矢量延迟/频率锁定环（VDFLL）的跟踪算法普遍采用延迟锁定环（DLL）和锁频环（FLL）鉴别器计算伪距和伪距率偏差观测量，由于锁频环鉴别器存在近似误差和一步延迟效应，在高动态环境下容易造成环路失锁。从直接估计卫星信号特征参数的角度出发，基于中频信号模型构建码相位和载波多普勒的极大似然代价函数，采用非迭代估计算法得到各通道码相位和多普勒频移的估计偏差，转换为卡尔曼滤波器的观测矢量，提出一种基于极大似然估计器（MLE）的矢量跟踪算法。理论分析和仿真结果表明：新算法结合了极大似然估计和矢量跟踪的优点，克服了FLL的延迟效应，与基于VDFLL的矢量环路相比，高动态环境下的跟踪稳定性更好，可以对被遮挡的卫星保持持续的跟踪。
程俊仁 , 刘光斌 , 张倩 , 范志良 . 基于极大似然估计器的GNSS矢量跟踪算法[J]. 航空学报, 2014 , 35(9) : 2559 -2567 . DOI: 10.7527/S1000-6893.2014.0027
Vector tracking is an advanced algorithm combining the signal tracking with the navigation of global navigation satellite system (GNSS) receivers. Traditional vector delay/frequency lock loop (VDFLL) generally loses of lock under high dynamic conditions because the pseudo-range and range-rate are always calculated by the delay lock loop (DLL) and frequency lock loop (FLL) discriminators, which may cause an approximation error and a one-step delay effort. Therefore, from the point of view of estimating the signal parameters directly, this paper proposes a vector tracking algorithm based on maximum likelihood estimator (MLE). This algorithm constructs the cost function of code delay and Doppler shift based on incoming signals firstly, and then calculates and converts the estimation errors to measurements by the noniterative filter method. Finally, all the measurements are input to a Kalman filter to complete the vector tracking. Theoretical analysis and simulation results show that compared to the traditional VDFLL, the new algorithm takes both advantages of the MLE and vector tracking, overcomes the delay efforts of FLL and performs a more robust tracking during the periods of signal blockage under high dynamic conditions.
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