顾及钟差变化率的GPS卫星钟差预报法

提出了一种基于钟差变化率拟合建模的卫星钟差预报方法。以附加周期项的线性或二次多项式作为基础模型对钟差变化率序列进行拟合,最优估计卫星钟差的趋势项系数,然后直接使用精密定轨得到的相应时刻的卫星钟差计算预报初始时刻的基准项系数,来建立卫星钟差的预报模型。以IGS发布的快速星历(IGR)的卫星钟差为试验数据,对GPS星座中各种型号的所有卫星钟差进行预报。结果表明:本文方法3、6、12与24h的预报精度分别可达0.43、0.58、0.90与1.47ns,相比于传统的基于钟差拟合的预报方法,精度分别提高69.3%、61.8%、50.5%与37.2%;与IGS发布的超快速星历(IGU)的预报钟差相比,钟差精度分别提高15.7%、23.7%、27.4%与34.4%。

A GPS Satellite Clock Offset Prediction Method Based on Fitting Clock Offset Rates Data

It is proposed that a satellite atomic clock offset prediction method based on fitting and modeling clock offset rates data.This method builds quadratic model or linear model combined with periodic terms to fit the time series of clock offset rates,and computes the model coefficients of trend with the best estimation.The clock offset precisely estimated at the initial prediction epoch is directly adopted to calculate the model coefficient of constant.The clock offsets in the rapid ephemeris (IGR)provided by IGS are used as modeling data sets to perform certain experiments for different types of GPS satellite clocks.The results show that the clock prediction accuracies of the proposed method for 3,6,12 and 24 h achieve 0.43,0.58,0.90 and 1.47 ns respectively,which outperform the traditional prediction method based on fitting original clock offsets by 69.3%,61.8%,50.5% and 37.2%.Compared with the IGU real-time clock products provided by IGS,the prediction accuracies of the new method have improved about 15.7%, 23.7%,27.4% and 34.4% respectively.