Real-time LEO satellite precise orbit and clock determination: Strategies and Challenges
Citation
Source Conference
Faculty
School
Collection
Abstract
To realize the various benefits brought by Low Earth Orbit (LEO) satellites in single-receiver high-precision GNSS-based Positioning Navigation and Timing (PNT) services, LEO satellite orbits and clocks need to be processed and delivered to users in real-time with precision of a few centimeters. While post-processing of cm-level LEO satellite orbits and clocks can be widely achieved, real-time processing faces various Challenges. When the number of LEO satellites increases, the observation data downlinked to the processing center may experience large and complicated discontinuities and incompleteness depending on the downlinking strategies. Even with the observations downlinked in real-time, the LEO satellite clock precision tends to be very sensitive to the continuity and quality of the GNSS real-time products. This study first introduces the procedure for ground-based cm-level real-time LEO satellite Precise Orbit Determination (POD), including near-real-time POD, short-term prediction, and ephemeris fitting/broadcasting. Next, the short-term predicted orbits and long-term predicted clocks of LEO satellites are introduced and properly constrained in filter-based real-time LEO satellite clock determination to achieve a precision of about 0.2 ns. Strategies to deal with sub-optimal observation data and GNSS products are explained. With the proposed methods, a Signal-In-Space Ranging Error at sub-dm to 1 dm can be achieved in practice.
Related items
Showing items related by title, author, creator and subject.
-
Xie, Wei; Su, Hang; Wang, Kan; Liu, Jiawei; El-Mowafy, Ahmed ; Yang, Xuhai (2024)Low Earth Orbit (LEO) satellites can augment the traditional GNSS-based positioning, navigation and timing services, which require real-time high-precision LEO satellite clock products. As the complicated systematic ...
-
Wang, Kan ; Liu, J.; Su, H.; El-Mowafy, Ahmed ; Yang, X. (2023)The augmentation of the Global Navigation Satellite System (GNSS) by Low Earth Orbit (LEO) satellites is proposed as an effective method to improve the precision and shorten the convergence time of Precise Point Positioning ...
-
Wang, Kan; Su, Hang; El-Mowafy, Ahmed ; Yang, Xuhai (2024)Low Earth Orbit (LEO) satellite orbits are required in real-time with high accuracy to enable the LEO augmentation to Global Navigation Satellite Systems (GNSSs) for its use in Positioning, Navigation and Timing (PNT). ...