Network-based precise orbit determination of broadband LEO satellites using Doppler-shift measurements

Abstract This paper presents a novel approach for precise orbit determination (POD) of broadband low Earth orbit (LEO) satellites employing Doppler shift measurements using a regional ground station network. Unlike traditional GNSS-based POD methods, our approach leverages the distinctive Doppler signatures generated by the high orbital velocities of LEO satellites, addressing the challenges posed by the signal characteristics and hardware constraints of broadband satellites. We develop a comprehensive mathematical framework for network-based POD and propose three distinct approaches to handle satellite clock synchronization: reference satellite selection, zero-mean constraint, and clock ensemble methods. Using simulated observations from a regional network of 18 continuously operating reference stations tracking Starlink satellites, we demonstrate the theoretical algorithmic potential for significant orbital accuracy improvements under simulation conditions, achieving theoretical upper bounds of mm-level positions (from 15 km initial errors), 10 −9 m/s velocities (from 1.5 km/s initial errors), and 2 × 10 −9 s/s clock drift precision (from 10 −8 s/s initial errors). These improvements translate to an enhancement in Doppler measurement accuracy from 1.5 × 10 3 m/s to 2 × 10 −9 m/s. The clock ensemble approach exhibits superior stability and robustness, though at a higher computational cost. These achievements confirm the theoretical potential of the developed model. Practical implementation is still constrained by hardware limitations, environmental factors, and signal processing complexities, which need further investigation. This research adds to the ongoing research in utilizing broadband LEO satellites for reliable positioning, navigation, and timing, particularly valuable for users where traditional GNSS signals may be compromised or insufficient.