金彪, 陈姗姗, 李祝莲, 李语强, 李子潇. SBAS GEO卫星URE精度及定位增强研究[J]. 武汉大学学报 ( 信息科学版). DOI: 10.13203/j.whugis20210091
引用本文: 金彪, 陈姗姗, 李祝莲, 李语强, 李子潇. SBAS GEO卫星URE精度及定位增强研究[J]. 武汉大学学报 ( 信息科学版). DOI: 10.13203/j.whugis20210091
JIN Biao, CHEN Shanshan, LI Zhulian, LI Yuqiang, LI Zixiao. SBAS GEO Satellite User Range Error and Position Augmentation Research[J]. Geomatics and Information Science of Wuhan University. DOI: 10.13203/j.whugis20210091
Citation: JIN Biao, CHEN Shanshan, LI Zhulian, LI Yuqiang, LI Zixiao. SBAS GEO Satellite User Range Error and Position Augmentation Research[J]. Geomatics and Information Science of Wuhan University. DOI: 10.13203/j.whugis20210091

SBAS GEO卫星URE精度及定位增强研究

SBAS GEO Satellite User Range Error and Position Augmentation Research

  • 摘要: 分析星基增强系统(SBAS) GEO卫星用户测距误差(URE),研究GEO卫星测距对导航定位性能的影响,可为SBAS系统设计和民航应用提供有益参考。本文利用WAAS、BDSBAS、GAGAN和MSAS等增强系统的SBAS信息对GPS和GEO卫星星历、时钟和观测值进行改正,固定测站位置,根据改正数残差方差加权计算接收机钟差,得到GEO卫星测距误差;将GEO卫星观测值纳入SBAS定位解算,评估GEO卫星测距对定位结果的影响。通过实测数据分析,WAAS GEO卫星URE优于1.6m; BDSBAS3颗GEO卫星分别存在14.32m、12.64m和17.44m的系统偏差,经系统性误差改正后,GEO卫星URE优于2.9m; GAGAN和MSASGEO卫星URE分别优于13.9m和3.2m。当GPS卫星数较少时,联合GEO卫星观测值进行SBAS解算能够有效减小定位保护级,提升系统可用性。

     

    Abstract: Satellite Based Augmentation System (SBAS) improves the positioning accuracy and integrity by broadcasting ephemeris corrections and associated integrity parameters through Geostationary Earth Orbit (GEO) satellites. SBAS GEO satellite can also be used as a ranging source together with Global Positioning System (GPS) satellites to improve the system performance. User range error (URE) of the GEO satellite and their effect on positioning results are investigated. URE of SBAS GEO and GPS satellite is determined by weighting the observation residuals which are derived with fixed station coordinates. SBAS messages are applied to correct the orbit and clock errors contained in broadcast ephemeris and the ionosphere delay. Ranging data from GEO satellite is engaged in the SBAS positioning process to explore the impact on positioning accuracy, integrity and availability. SBAS messages broadcast by Wide Area Augmentation System (WAAS), BeiDou Satellite Based Augmentation Systems (BDSBAS), GPS Aided Geo Augmented Navigation (GAGAN) and MTSAT (Multi-functional Transport Satellite) Satellite based Augmentation System (MSAS) and real data from International GNSS Service (IGS) stations are applied to perform the assessment. European Geostationary Navigation Overlay Service (EGNOS) and System for Differential Corrections and Monitoring (SDCM) are not included because of the absence of the ranging capability. It was found that WAAS GEO satellite has the best performance with ranging accuracy better than 1.6m. The 99.9% error bound is less than 6.8m while the broadcast User Differential Range Error (UDRE) for the GEO satellite is 7.5m, which meets the integrity requirement. The 3 GEO satellites of BDSBAS show ranging biases of 14.32m, 12.64m and 17.44m respectively, and the accuracy is better than 2.9m. After removing the bias, the related 99.9% error bound is 8.60m, 7.80m and 11.60m which suggests an UDRE of 11~12. An URA of 15 is broadcast in message type 9 for the BDSBAS GEO satellites. URE of the GAGAN GEO satellite is better than 13.9m and for MSAS it is better than 3.2m. The UDRE of GAGAN and MSAS is 14. URE of GPS satellite after augmented by SBAS is also calculated for comparison purpose. Ranging accuracy of GPS is 0.60m, 0.53m, 0.21m and 0.34m for WAAS, BDSBAS, GAGAN and MSAS respectively. WAAS GEO satellite is selected to perform the positioning analysis whose UDRE is less than 14 so that it can be weighted properly in the solution. Engagement of GEO satellite in SBAS positioning will lead to lower Position Dilution of Precision (PDOP) and reduce the protection level especially for the blockage circumstance. The system availability of Localizer Performance with Vertical guidance 200 (LPV200) approach is improved from 99.984% to 99.997% with collaboration of 3 GEO satellites' observation. With sufficient GPS satellites, the combination of GEO satellites will decrease the positioning accuracy because of the relative larger range error. Results suggest that SBAS GEO ranging data should be included in the SBAS solution for aviation users.

     

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