Impact analysis of arc length in multi-GNSS ultra-rapid orbit determination based on the one-step method

Abstract

With the development of near real-time and real-time high-precision global navigation satellite system (GNSS) applications, users’ requirements for the accuracy and stability of ultra-rapid orbits have increased, especially for multi-constellation orbits. Generally, several factors affect the accuracy and stability of multi-GNSS ultra-rapid orbit determination; however, this study is focused only on analyzing the orbit arc length of ultra-rapid orbits of the GPS, GLONASS, BeiDou-2, and Galileo satellites based on the one-step method. To realize nearly ideal conditions in the process of analysis, one full year’s rapid orbit products during 2018 provided by the GeoForschungsZentrum multi-GNSS experiment analysis center were used as fitted observed orbits and also as a reference orbit for comparison to the predicted orbit. In terms of residual analysis of orbit difference and stability analysis of Helmert transformation parameters, the numerical results showed that the optimal orbit arc lengths of quad-constellation medium earth orbit (MEO) satellites for 6 h and 3 h predicted ultra-rapid orbits based on the one-step method were in the range of 44–45 h and 41–44 h, respectively. Overall, for both 6 h and 3 h predictions, when only considering the impact of the orbit arc length on the accuracy and stability of the orbit itself, 44 h can be considered as the overlapping optimal orbit arc length of quad-constellation MEO satellitesʼ ultra-rapid orbits generated by the one-step method. In addition, these ranges of orbit arc length can contribute to the multi-GNSS ultra-rapid orbit determination.

Improved Ultra-Rapid UT1-UTC Determination and Its Preliminary Impact on GNSS Satellite Ultra-Rapid Orbit Determination

“…GNSS satellite ultra-rapid orbit is the key in determining real-time precise orbits and achieving real-time precision point positioning (PPP) [4,5]. The accuracy and stability of GNSS satellite ultra-rapid orbit determination directly or indirectly affects and limits the performance and promotion of real-time PPP and related applications [6][7][8]. UT1 is the angle of the Earth's rotation about the CIP (Celestial Intermediate Pole) axis defined by its conventional linear relation to the Earth Rotation Angle (ERA), and UT1-UTC is the difference between the UT1 parameter derived from observations and UTC (Coordinated Universal Time) [9].…”

Analysis and improvement of the Bancroft algorithm for GNSS satellite orbit determination

“…Precise ephemeris information is typically obtained using GNSS observations and initial trajectories with poor accuracy [13,14]. In addition, based on the precise ephemeris, high-precision prediction values can be extrapolated in a short period of time, and the accuracy will decrease significantly as the extrapolation time increases [15,16].…”