GPS-SBAS-Based Orbit Determination for Low Earth Orbiting Satellites

• Published in: International journal of aerospace engineering 2023-10, Vol.2023, p.1-9
• Main Authors: Kim, Mingyu, Kim, Jeongrae
• Format: Article
• Language: English
• Subjects: Accuracy; Aerospace engineering; Aircraft; Dynamic models; Error correction; Error reduction; Extended Kalman filter; Global navigation satellite system; Global positioning systems; GPS; GRACE (experiment); Ionosphere; Kinematics; Low earth orbit satellites; Low earth orbits; Orbit determination; Real time; Satellite navigation systems; Service areas; Space Based Augmentation Systems; Synchronous satellites; Time use
• ISSN: 1687-5966; 1687-5974
• DOI: 10.1155/2023/3033205

A space-based augmentation system (SBAS) provides real-time GNSS correction signals via geostationary satellites for near-ground GNSS users. To use the SBAS correction for low Earth orbit (LEO) satellites, the correction, especially the ionosphere correction, must be adjusted for the LEO altitude. We apply modified SBAS data to LEO satellite onboard navigator to improve the positioning accuracy of a LEO satellite for possible real-time use. The onboard navigator requires high positioning reliability, and code pseudoranges, rather than phase pseudoranges, are used for the primary measurements. The Galileo NeQuick G model is used to determine the real-time conversion factor of the SBAS ionosphere correction for a LEO satellite. The GPS L1 data from GRACE satellite are combined with the SBAS data from the ground receiver. The onboard navigator combines the precise satellite dynamic model with an extended Kalman filter to improve positioning accuracy and stability. The kinematic positioning method, which uses the weighted least square method without the dynamic model, is also performed for comparison. The SBAS correction reduces the positioning error in both the kinematic positioning and the dynamic positioning. The positioning error reduction of the GPS and WAAS case over the GPS-only case is 25.2% for the kinematic method and 30.6% for the dynamic method. In the case of the dynamic method with the SBAS corrections, the positioning error remains smaller than that of the GPS-only dynamic method even after the satellite has left the SBAS service area.