PAN Xiong,HUANG Weikai,WANG Cong,et al.BDS-3 Clock Error Prediction Algorithm Based on Semi-parametric-SVM Combined Model[J].Geomatics and Information Science of Wuhan University,2025,50(4):617-627.
PAN Xiong,HUANG Weikai,WANG Cong,et al.BDS-3 Clock Error Prediction Algorithm Based on Semi-parametric-SVM Combined Model[J].Geomatics and Information Science of Wuhan University,2025,50(4):617-627.DOI:,10.13203/j.whugis20220787
BDS-3 Clock Error Prediction Algorithm Based on Semi-parametric-SVM Combined Model
针对卫星钟差序列中非线性特性较为复杂的问题,为了有效地分离周期项改正误差和顾及不能函数化的因素,提高钟差预报的精度,将钟差周期项模型扩充到半参数模型。利用核估计方法将窗宽参数与模型参数解算综合考虑,建立了半参数变系数模型,综合支持向量机进行卫星钟差数据的参数解算、周期项改正分离、异常值识别和残差拟合。首先,利用泰勒展开式对非参数分量进行修正,引入核估计方法,建立了半参数变系数模型;然后,构造分值检验统计量进行异常值识别,提出了一种综合分值检验统计量的钟差异常值识别方法;最后,为了避免对观测值过拟合或拟合不足,对经过预处理的残差利用支持向量机进行拟合,提高模型的预报精度。采用北斗三号全球卫星导航系统(BeiDou-3 global navigation satellite system,BDS-3)的钟差数据与常用方法进行了对比实验,验证了新模型的可靠性。实验结果表明,建立的模型能够精确高效地对BDS-3钟差异常值进行定位,识别并分离周期项改正,有效地提高BDS-3钟差数据预处理的质量和效率。建立的组合模型预报精度优于传统的二次多项式模型、周期项模型和半参数模型,对于1 h、6 h和12 h预报,新模型的钟差数据的预报平均精度优于0.164 ns。
Abstract
Objectives
2
The nonlinear characteristics of satellite clock offset sequences are complex. To effectively separate the correction error of the periodic term while accounting for non-functionalized factors and improving the accuracy of clock bias prediction
this study extends the clock error periodic term model to a semi-parametric clock error model.
Methods
2
By employing the kernel estimation method
both the window width parameter and parameter solution of the kernel function are comprehensively considered
resulting in the establishment of a semi-parametric varying coefficient model. First
the kernel estimation method is introduced
and the parameter components are modified by Taylor expansion. By synthesizing the kernel function and window width parameters
the parameters and periodic term correction estimates of the semi-parametric varying coefficient model are obtained via a three-step estimation method. Then
score test statistics are constructed to detect outliers
and an outlier identification method is proposed for the semi-parametric varying coefficient clock difference prediction model with periodic correction. Finally
to avoid over-fitting or under-fitting of the observed values
a support vector machine is used to further fit the pre-processed clock residual data
thereby improving the model's fitting and prediction accuracy. The reliability of the proposed model is verified by comparing BDS-3 satellite clock difference data with conventional methods.
Results
2
Experimental results show that the proposed model can accurately and efficiently determine the constant value of the BeiDou-3 global navigation satellite system (BDS-3) clock difference
identify and separate periodic term corrections
and significantly improve the quality and efficiency of BeiDou navigation satellite system clock difference data preprocessing. The prediction accuracy of the proposed combined forecast model surpasses that of the traditional quadratic polynomial model
periodic term model
and semi-parametric model. For 1 h
6 h
and 12 h forecasts
the average prediction accuracy for BDS-3 satellite clock difference data is better than 0.164 ns.
Conclusions
2
The proposed model provides a high level of precision and efficiency in preprocessing and predicting BDS-3 satellite clock difference data. It demonstrates superior performance compared to traditional models and offers significant potential for broader applications in satellite clock offset prediction tasks.
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