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Abstract The bottleneck of Precise Point Positioning (PPP) is the long convergence time for achieving the centimeter accuracy. Some researchers put forward to improve the diversity of available satellites’ geometric distribution and reduce the correlation of observation data by deploying the Low Earth Orbit (LEO) constellations in addition to the medium and high-orbit satellites. The prerequisite is to get the precise orbit products of all these orbiting satellites. This paper studies the combined precise orbit determination for high-, medium-, and low-orbit navigation satellite systems. In order to investigate the theory and algorithms of the high–medium–low POD and to study the effect of LEO to the POD of high-orbit satellites and the influence of ground data from LEO to its own POD, we simulate all the data, including high orbit to low orbit, medium orbit to low orbit, high orbit to ground stations, medium orbit to ground stations, and low orbit to ground stations. The results show that the combined POD can improve the precision of high-orbit satellites significantly, especially for the along-track component, which can reach to sub-decimeter even centimeter level. Also, the precision of LEO POD can be improved with the data from ground stations.







Keywords High, medium, and low orbit Navigation satellite Combined precise orbit determination Geometric distribution




H. Ge
B. Li (&)
Y. Shen
L. Nie College of Surveying and Geo-Informatics, Tongji University, Shanghai 200092, China e-mail: [email protected] H. Ge e-mail: [email protected] H. Ge
M. Ge
H. Schuh Department of Geodesy, GeoForschungsZentrum (GFZ), 14473 Potsdam, Germany © Springer Nature Singapore Pte Ltd. 2017 J. Sun et al. (eds.), China Satellite Navigation Conference (CSNC) 2017 Proceedings: Volume III, Lecture Notes in Electrical Engineering 439, DOI 10.1007/978-981-10-4594-3_15

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1 Introduction Nowadays, besides USA GPS and Russian GLONASS, the European Galileo and Chinese BeiDou are developing rapidly. The Galileo constellation will consist of 30 satellites in three orbital planes [10]. By the end of 2020, BeiDou system will be completed for global service, consisting of 5 Geostationary Earth Orbit (GEO) satellites, 27 Medium Earth Orbit (MEO) satellites, and 3 Inclined Geosynchronous Satellite Orbit (IGSO) satellites [4]. At that time, there will be over 100 satellites providing Positioning, Navigation, and Timing (PNT) service. Since the slow variation of GNSS satellites’ geometry with respect to a ground station, it takes nearly several minutes or even hours to achieve centimeter accuracy of PPP. Due to the poor geometry, there are some challenges for the POD of different constellations of GNSS satellites. Taking BDS IGSO and GEO satellites for example, they operate in higher orbits than MEO satellites and their geometric variations are less sensitive to the ground stations, especially for GEO satellites because of its geostationary characteristic, which leads to the great challenge for GEO POD. In re