北斗系统GEO/IGSO/MEO卫星观测信息随机特性评估与分析

Evaluation and analysis of stochastic modeling of BeiDou GEO/IGSO/MEO satellite observation

首先从参数估计、精度评定和质量控制角度论证了在精密定位中随机模型的重要性;然后基于短基线单差观测模型,采用严密的方差分量估计方法计算了不同频率、不同卫星的相位和伪距观测值精度,任意频率之间的交叉相关性以及不同频率的相位和伪距观测值在不同时间间隔上的时间相关性;随后分析了随机模型对基线精度和整体检验统计量的影响。结果表明:北斗用户接收机数据精度都与高度角相关,建议采用高度角指数加权函数;北斗二号3个频率相位观测值之间存在不同程度的相关性,其他类型观测值之间的交叉相关性不明显,不同频率的相位和伪距观测值时间相关性较明显,高精度应用中需关注。另外,正确的随机模型计算的基线精度更接近理论精度。本文为用户正确认识北斗系统3个类型卫星观测信息、正确使用北斗系统提供支撑。

Firstly,the importance of stochastic model in precise positioning is demonstrated from the perspectives of parameter estimation,accuracy evaluation and quality control.Then,based on the single-difference functional model,the rigorous variance component estimation(VCE)method is used to allow the estimation of satellite-specific variances,cross correlations between two arbitrary frequencies,as well as the time correlations for phase and c+ode observations per frequency.The influence of the stochastic model on baseline precisions and the overall statistics was subsequently analyzed.The results show that the observation precisions of the BeiDou user receiver are overall elevation-dependent for phase and code of all frequencies.It is recommended to use the elevation-dependent exponent weighting model;there are different degrees of correlation between the three frequency phase observations,and the cross correlation between other types of observations is not obvious.The time correlation between phase and code observations of different frequencies is obvious,and attention should be paid to high-precision positioning.Furthermore,the baseline precisions that used the correct stochastic model match the theoretical ones very well for the three baseline components.The paper provides support for users to correctly understand the three types of satellite observation of the BeiDou system and correctly apply the BeiDou system.