Multipath error detection and correction for GEO/IGSO satellites  

作　　者：WU XiaoLi ZHOU JianHua WANG Gang HU XiaoGong CAO YueLing 

机构地区：[1]Shanghai Astronomical Observatory,Chinese Academy of Sciences Shanghai 200030,China [2]Beijing Global Information Application and Development Center,Beijing 100094,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2012年第7期1297-1306,共10页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National High Technology Research and Development Program of China (863) (Grant Nos.2009Z12A324 and 2009AA12Z328);the National Natural Science Foundation of China (Grant Nos. 10703011, 11073047 and 11033004);the Science and Technology Commission of Shanghai (Grant No. 06DZ22101)

摘　　要：Constellations of regional satellite navigation systems are usually constituted of geostationary satellites (GEO) and inclined geostationary satellites (IGSO) for better service availability. Analysis of real data shows that the pseudorange measurements of these two types of satellites contain significant multipath errors and code noise, and the multipath for GEO is extremely serious, which is harmful to system services. In contrast, multipath error of carrier phase measurements is less than 3 cm, which is smaller than the multipath of pseudorange measurements by two orders of magnitude. Using a particular combination of pseudorange and dual-frequency carrier phase measurements, the pseudorange multipath errors are detected, and their time varying features are analyzed. A real-time multipath correction algorithm is proposed in this paper, which is called CNMC (Code Noise and Multipath Correction). The algorithm decreases the influence of the multipath error and therefore ensures the performance of the system. Data processing experiments show that the multipath error level may be reduced from 0.5 m to 0.15 m by using this algorithm, and 60% of GEO multipath errors and 42% of IGSO multipath errors are successfully corrected with CNMC. Positioning experiments are performed with a constellation of 3 GEO plus 3 IGSO satellites. For dual-frequency users the East-West position accuracy is improved from 1.31 m to 0.94 m by using the CNMC algorithm, the South-North position accuracy is improved from 2.62 m to 2.29 m, and the vertical position accuracy is improved from 4.25 m to 3.05 m. After correcting multipath errors, the three-dimensional position accuracy is improved from 5.16 m to 3.94 m.Constellations of regional satellite navigation systems are usually constituted of geostationary satellites （GEO） and inclined geostationary satellites （IGSO） for better service availability. Analysis of real data shows that the pseudorange measurements of these two types of satellites contain significant multipath errors and code noise, and the multipath for GEO is extremely se- rious, which is harmful to system services. In contrast, multipath error of carrier phase measurements is less than 3 cm, which is smaller than the multipath of pseudorange measurements by two orders of magnitude. Using a particular combination of pseudorange and dual-frequency carrier phase measurements, the pseudorange multipath errors are detected, and their time varying features are analyzed. A real-time multipath correction algorithm is proposed in this paper, which is called CNMC （Code Noise and Multipath Correction）. The algorithm decreases the influence of the multipath error and therefore ensures the performance of the system. Data processing experiments show that the multipath error level may be reduced from 0.5 m to 0.15 m by using this algorithm, and 60% of GEO multipath errors and 42% of IGSO multipath errors are successfully correct- ed with CNMC. Positioning experiments are performed with a constellation of 3 GEO plus 3 IGSO satellites. For du- al-frequency users the East-West position accuracy is improved from 1.31 m to 0.94 m by using the CNMC algorithm, the South-North position accuracy is improved from 2.62 m to 2.29 m, and the vertical position accuracy is improved from 4.25 m to 3.05 m. After correcting multipath errors, the three-dimensional position accuracy is improved from 5.16 m to 3.94 m.

关 键 词：multipath error carrier smoothing pseudorange GEO satellite position error 

分 类 号：V551[航空宇航科学与技术—人机与环境工程] TV697.23[水利工程—水利水电工程]