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星基增强导航系统(SBAS,Satellite Based Augmentation System)通过向用户提供用户差分距离误差(UDRE,User Differential Range Error),来保证广播星历和星钟改正数的精度并增强用户的完好性性能.给出了一种用于主控站的UDRE计算方法,提出了卫星监视几何精度因子(SSDOP,Satellite Surveillance Dilution of Precision)的概念.基于UDRE和SS-DOP的表达式,通过数学推导发现UDRE受到SSDOP和限制因子的影响,而限制因子可以用其统计平均值0.7438来替代,建立了由SSDOP估计UDRE的表达式.仿真结果表明:利用SS-DOP估计出的UDRE值,其误差不超过0.8 m,能够反映出当前卫星UDRE的特性,可以作为用户在无法接收完好性信息时快速推算UDRE的一种可行手段.
The Satellite Based Augmentation System (SBAS) ensures the accuracy of broadcast ephemeris and satellite clock corrections and enhances the user’s integrity performance by providing the user with User Differential Range Error (UDRE). A UDRE calculation method for master station is proposed and the concept of Satellite Surveillance Dilution of Precision (SSDOP) is proposed. Based on the expression of UDRE and SS-DOP, UDRE is found through mathematical deduction. SSDOP and limiting factors, and the limiting factor can be replaced by its statistical average of 0.7438, and the expression of UDRE estimated by SSDOP is established.The simulation results show that the error of UDRE estimated by SS-DOP is less than 0.8 m , Which can reflect the characteristics of the current satellite UDRE can be used as a feasible means for users to quickly calculate UDRE when they can not receive intact information.