北斗系统UERE及定位精度评估

用户测距误差（URE）与用户设备误差（UEE）是影响定位精度的主要因素.民航是北斗系统的高端用户，监测其对民航机场的覆盖性和服务性能十分必要.本文根据华东、华南、华北、西北地区4个民航机场观测站的北斗实测数据，分析了各机场卫星的可见性.根据URE的解算方法、电离层修正模型、对流层修正模型以及定位精度的评估方法，给出了对应的性能评估结果.研究发现:可见星数均在6～14颗，满足定位要求； 95%置信度下，电离层延迟优于7.50m，对流层延迟优于13.28m，地球静止轨道卫星（GEO）、倾斜地球同步轨道卫星（IGSO）、中圆轨道卫星（MEO）卫星的URE值分别优于2.36m，1.72m，2.59m，满足北斗规范的要求；95%置信度下，定位精度水平方向优于3.63m，垂直方向优于6.98m.结果表明北斗系统在民航机场监测站的覆盖性及服务性能良好. 

Evaluation on UERE and Positioning Accuracy of BDS

User Ranging Error (URE) and User Equipment Error (UEE) are the main factors affecting the positioning accuracy. Civil aviation is the high-end user of BeiDou Navigation Satellite System (BDS). It is necessary to monitor the coverage and service performance of BDS at civil aviation airports. Based on the measured data of BDS at four civil aviation airport observatories, this paper introduces the satellites visibility of each airport, URE solution method, ionospheric delay correction model, tropospheric delay correction model and the evaluation of positioning accuracy. The results show that the number of visible satellites is from 6 to 14, which meets the positioning requirements. At 95% confidence level, the ionospheric delay is better than 7.50m, the tropospheric delay is better than 13.28m, and the URE values of Geostationary Earth Orbit (GEO) satellites, Inclined Geosynchronous Orbit (IGSO) satellites and Medium Earth Orbit (MEO) satellites are better than 2.36m, 1.72m and 2.59m respectively, which meet the requirements of Beidou open service performance specifications. At 95% confidence level, the positioning accuracy is better than 3.63m in the horizontal direction and better than 6.98m in the vertical direction. The coverage and service performance of BDS at the civil airport monitoring stations are good.