星载GPS伪距测量数据质量分析

Data Quality Analysis of Space-borne GPS Code Measurements

研究了星载GPS伪距测量精度评定方法以及粗差的探测方法,用自编的软件对CHAMP卫星和SAC-C卫星的星载GPS实测数据进行了详细的分析。结果表明：随着卫星高度角的不同,多路径效应与伪距测量噪声对星载GPS伪距测量精度的影响在0.5-3.0 m之间;CHAMP和SAC-C星载GPS观测数据中,伪距粗差观测值所占的比例分别达到1.2%和3.0%。

The accuracy of satellite real-time orbit determination is directly depended on the data quality of spaceborne GPS code measurements. In this paper, P-code multipath errors and noise are estimated with linear combinations of code and carrier-phase measurements, meanwhile pseudo-range outliers and anomalies are isolated by data preprocessing before single point positioning. The experimental results from three days data set collected from CHAMP and SAC-C missions are presented. These results have demonstrated that P-code muhipath errors and noise vary between 0.5 m at high elevations and 3.0 m at less than 10° elevations, that outliers and anomalies of ionosphere-free P-code linear combinations from CHAMP and SAC-C amount to 1.2% and 3% of the total number of observations respectively. More than 70% of these outliers are less than 100 m, and some outliers come from GPS satellites of high elevation. These results of data analysis contribute to support the design of optimal data editing and weighting strategies in real-time and precise orbit determination applications.