The Satellite Category-Related Weighted Method of BeiDou
PPP Based on Post-fit Residual
Xiao Chang, Junhong Liu, Defeng Gu, Xiaojun Duan
College of Science. National University of Defense Technology, Changsha, China
gudefeng@nudt.edu.cn.
Abstract: Indifferent from the navigation constellation of Global Positioning System (GPS), BeiDou
Navigation Satellite System (BDS) consists of three categories of satellites which are GEOs, IGSOs and
MEOs. And the three types of satellites show notable difference in positioning residual owing to the orbit
accuracy, the multipath effect and other factors. This article studies the strategy of weighted method and the
edition of the residual. In terms of the former one, a new weighted method of BeiDou PPP based on the
posterior residual is put forward: with the help of statistical analysis of positioning residuals, the observed
data is divided into two groups as GEOs and IGSOs/MEOs, and the relative weight is deduced for each
group. As for the edition of residual, in consideration of the fact that the residual of GEOs is larger than that
of the other two kinds of satellites and doing abnormal detection using “3” principle for all satellites
together may cause losing of useful GEOs data while leaving some abnormal data of the other two kinds, we
deal with the residual of three satellites respectively to lower the weight of abnormal data and improve the
accuracy of PPP on the basis of the first step. By using the one-month observed data from 9 stations of
MGEX with BeiDou orbit and clock products provided by GFZ, the positioning accuracy gets improved to
be 3.2 cm、2.8 cm and 7.1 cm in E, N, U directions respectively with new weighted methods in this paper,
compared to the former accuracy with 3.7 cm, 3.1cm and 7.5 cm in three directions.
Keywords: BeiDou; Precise Point Positioning (PPP); Weighted method based on post-fit method; The edition of
the residual
基于验后残差的北斗精密单点定位卫星分类加权方法
昌虓,刘俊宏,谷德峰,段晓君
国防科学技术大学理学院,长沙,中国,
410073
gudefeng@nudt.edu.cn
【摘要】不同于GPS卫星导航星座,北斗卫星导航星座由GEO,IGSO和MEO三类卫星组成。受轨道精
度,多径效应等因素的影响,三类卫星的定位残差差异较大。本文研究了两个方面的内容:在加权策
略方面,提出了基于验后定位残差的北斗精密单点定位加权方法。通过对三类卫星精密单点定位的残
差进行统计分析,根据残差差异将观测数据按GEO卫星和IGSO/MEO卫星分为两类,并给出了这两类
卫星的相对权重;在残差编辑方面,由于GEO卫星较其他两类卫星的定位残差更大,对所有卫星按3
准则进行统一的异常值检测时可能使GEO卫星正常数据被大量剔除,而IGSO、MEO卫星的部分异常数
据无法有效剔除,为此在上述验后残差加权的基础上对GEO卫星、MEO卫星和IGSO卫星分别进行残差
编辑,降低异常观测数据的权重,以提高北斗精密单点定位解的精度。选取9个MGEX地面观测站一个
月的观测数据和GFZ提供的北斗卫星轨道和钟差进行解算,利用卫星分类加权方法和残差编辑方法后
E、N、U方向精度分别从3.7 厘米、3.1 厘米和7.5 厘米提高到3.2 厘米、2.8 厘米和7.1 厘米。
【关键词】北斗,精密单点定位,验后残差加权,残差编辑
1 引言
北斗卫星导 航系统(BeiDou Navigation Satellite
System,BDS)是我国自主研发的全球导航定位系统,
不同于GPS(Global Positioning System),该系统星座由
地球静止轨道卫星(Geostationary Earth Orbit,GEO)、
倾 斜 地 球 同 步 轨 道 卫 星 (Inclined Geosynchronous
Orbit,IGSO)和地球中轨卫星(Medium Earth Orbit,
MEO)组成。自1994年正式进行试验系统的研制起,
如今北斗已经发展成为对亚太地区全面覆盖,具备定
位、授时和短报文通信功能的区域导航系统,并计划
于2020年完成全面建设,实现全球范围的公开服务
[1]
。
随着北斗导航系统的日益成熟,越来越多的学者着眼
于对北斗系统的信号质量,北斗卫星钟差,轨道精度
以及绝对定位
[2]
等方面开展研究。其中,北斗卫星的
轨道精度的研究和北斗精密单点定位研究得到了广泛
资助信息:国家自然科学基金(61370013,91438202)和iGMAS资
助