LEO星载GPS PPP定位周期误差分析及处理策略

Analysis of PPP period error of LEO satellite spaceborne GPS

采用GRACE卫星的星载GPS观测数据进行动态精密单点定位解算,发现定位误差存在明显的周期特性,第一个特性为每间隔四天的定位误差序列的波形基本重合,第二个特性为相邻两天定位误差序列有横坐标平移的趋势.基于此,提出了两种消除周期性误差的方法,分别为基于中位数建模的周期项误差剔除方法和基于平移预报的周期项误差剔除方法.前者对一组数据序列中的中间序列的精度提升较为明显,后者对精度的提升在整体上较为稳定,对两种方法的改善效果进行综合分析,最终可以将定位精度从5 dm提高到2 dm,三个方向的均方根(RMS)值得到显著降低.

Using space-borne GPS observation data of GRACE for kinematic precise point positioning,it is found that the positioning error has obvious periodic characteristics.The first characteristic is that the waveforms of the positioning error sequences at intervals of four days basically coincide,and the second characteristic is that the positioning error sequences of two adjacent days have a tendency to shift along the abscissa.Based on the above two characteristics,two methods for eliminating periodic errors are proposed,which are the periodic item error elimination method based on median modeling and the periodic error elimination method based on translation prediction.The former improves the accuracy of the intermediate sequence in a group of data series obviously,while the latter is more stable on the whole.A comprehensive analysis of the improvement effect of the two methods is carried out.Finally,the positioning accuracy is improved from 5 dm to 2 dm.The RMS values in the three directions are obtained significantly reduced.