GNSS Satellite Clock Real-Time Estimation and Analysis for Its Positioning
Real-time and high-precision Multi-GNSS positioning technical has been playing an important role in the determination of low earth orbiter (LEO) and monitoring of geologic hazards. The key concern should be on the achievement of the high-precision satelli
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GNSS Satellite Clock Real-Time Estimation and Analysis for Its Positioning Bingbing Duan, Junping Chen, Jiexian Wang, Yize Zhang, Jungang Wang and Li Mao
Abstract Real-time and high-precision Multi-GNSS positioning technical has been playing an important role in the determination of low earth orbiter (LEO) and monitoring of geologic hazards. The key concern should be on the achievement of the high-precision satellite orbit and clock products. In this paper, real-time clock estimation strategy was introduced. Based on the mean square root filtering method, dates via 35 global uniformly distributed IGS observations were used to estimate real-time satellite clock errors of GPS and CLONASS, which was proved 0.2 ns and 0.8 ns respectively. The outcomes were verified again via precise point positioning. Consequently, compared with the positioning accuracy via only GPS, that of GPS and GLONASS improved 26 % in X direction, 40 % in Y direction and 2 % in Z direction. The convergence time shorten 2 to 4 times as well.
Keywords GPS GLONASS Real-time clock estimation tioning Mean square root filtering
Combination posi-
62.1 Instruction Precise point positioning (PPP) of Global navigation satellite system (GNSS) can achieve centimetre-level accuracy for static positioning and decimetre-level for kinematic respectively. Its precision depends mainly on the quality of satellite orbit B. Duan (&) J. Wang Y. Zhang J. Wang L. Mao College of Surveying and Geo-informatics Building, Tongji University, Shanghai, China e-mail: [email protected] J. Chen Shanghai Astronomical Observatory, Chinese Academy of Sciences, SHAO, ShangHai, China e-mail: [email protected]
J. Sun et al. (eds.), China Satellite Navigation Conference (CSNC) 2014 Proceedings: Volume III, Lecture Notes in Electrical Engineering 305, DOI: 10.1007/978-3-642-54740-9_62, Ó Springer-Verlag Berlin Heidelberg 2014
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and clock. At present, the precision of GPS broadcast ephemeris is 7 ns for clock error (http://igscb.jpl.nasa.gov/components/prods.html) while GLONASS is 15 ns, which is far from the requirement of precise positioning [1]. From November 5, 2000 (GPS Week 1087), International GNSS Service(IGS) began to offer ultrarapid(IGU) services, but the predicting part is still not accurate enough (5 ns). Besides that, RTG (Real-time GIPSY) developed by JPL analysis center could estimate real-time GPS orbit and clock products based on 60 NASA global networks (http://galia.gdgps.net/igds). The precision is 1 ns and has about 4 seconds latency, but the production is secretive [2]. Natural Resources Canada(NRCan, http://www.cdgps.com) can also estimate real-time GPS clock using ultra-rapid orbit but need to be authorised [3]. Till now, almost all the real-time GPS clock products are paid and GLONASS clock products provided by CLONASS control center (MCC, ftp.glonass-iac.ru/MCC) and Shanghai Astronomical Observatory (SHAO, http://202.127.29.4/shao_gnss_ac/) could not satisfy the need of precise positioning. So,
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