Performance of Galileo: Global coverage, precise orbit determination, and precise positioning

摘要

As one of the major global navigation satellite systems (GNSSs), the performance of the Galileo Satellite Navigation System (Galileo) has been of pressing concern. By the end of June 2018, there were 17 operational satellites that provide navigation and positioning services. However, there is little research evaluating the performance of the Galileo single-system in terms of the average satellite coverage and precise positioning. To address this, this study firstly uses the number of visible satellites to analyze the global average satellite coverage of Galileo. Then different data processing strategies are used to evaluate the accuracy of the Galileo satellite orbit and clock. Finally, the performances of precise point positioning (PPP) and baseline solutions obtained using the Galileo single-system are analyzed. Results show that the number of visible Galileo satellites globally is between 6 and 7 and the time percentage where the number of visible Galileo satellites is greater than or equal to 4 is more than 90% globally. For the orbit determination of Galileo satellites, the Galileo/GPS combined solution is better than that of the Galileo single-system. Using the GeoForschungsZentrum Potsdam (GFZ) multi-GNSS orbit product (indicated by GBM) as a reference, the root mean squares (RMSs) of three-dimension and radial component of Galileo/GPS three-day combined solution are 4.4 cm and 1.8 cm, respectively. The accuracy of the Galileo/GPS single-day combined solution is almost the same as that of the Galileo/GPS three-day combined solution. For the Galileo satellite clock, the Galileo/GPS combined solution provides a better result than the Galileo single-system solution. The convergence times of the static and kinematic PPP solutions of the Galileo single-system are both about 2 h. The average the RMSs of the east (E), north (N), and up (U) components of the static Galileo-only PPP solution are 1.9 cm, 0.5 cm, and 2.0 cm, respectively. Those of the kinematic Galileo-only PPP solution are 2.1 cm, 1.4 cm, and 2.6 cm, respectively. Moreover, the baseline solution accuracy of the ultra-short baseline (48 m) of the Galileo single system is comparable to GPS. For both static and kinematic solutions, the standard deviations (STDs) of the horizontal and vertical components are better than 6 mm and 8 mm, respectively. The accuracy of baseline solution results of the short baseline (1850 m) is poorer. For both static and kinematic solutions, the STDs of the horizontal and vertical components are better than 1.3 cm and 1.9 cm, respectively. (C) 2019 COSPAR. Published by Elsevier Ltd. All rights reserved.