Kobel, Cyril (2023). Incorporation of LEO GNSS observations into global network solutions. (Thesis). Universität Bern, Bern

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Abstract

This research focuses on specific aspects of geodesy with the aim of deepening the understanding of Earth's dynamic geodetic parameters and refining the precision and completeness of global network solutions. The work comprises various investigations, each addressing key aspects of geodetic research and contributing to a broader understanding. The central approach involves the integration of observations from Global Navigation Satellite Systems (GNSS) collected by satellite-based receivers aboard Low Earth Orbiters (LEOs) into the determination of a global GNSS network solution. The focus is on the influence of integrating LEO-GNSS observations on resulting parameters such as GNSS and LEO orbits, geodetic parameters, such as Earth's center-of-mass coordinates and Earth rotation parameters, and ground station coordinates. Fundamental to this is the current state of realizing terrestrial reference frames (TRFs). The incorporation of LEO-GNSS observations addresses conceptual deficiencies in TRFs by considering the gravity field. Satellites in low Earth orbits play a crucial role, acting in the role of "Space Ties", and being highly sensitive to the gravitational field. These satellites become integral components for various satellite geodetic techniques, promising a comprehensive and improved representation of Earth's geodetic reference frame. One aspect of the work involves an examination of traditional methods for precise orbit determination (POD) of LEOs using observations from the Global Positioning System (GPS). Traditionally relying on fixed GPS orbits and clock corrections derived from ground-based receivers, this work highlights the potential of integrating LEO-GNSS observations into global network solutions. A comprehensive analysis, including data from LEOs, equipped with dual-frequency GNSS receivers, is methodically scrutinized through a joint least-squares adjustment process, resulting in a combined GNSS-LEO solution. The analysis shows a significant improvement in the observability of the estimated geodetic parameters. Acknowledging the observational advantages of LEO satellites due to their proximity to the Earth's surface, this work emphasizes their complementary role alongside established systems like GPS. The investigation carefully analyzes the potential for further qualitative enhancements in the framework of network solutions when LEOs are seamlessly integrated, particularly in conjunction with multiple GNSS systems.

Item Type:	Thesis
Dissertation Type:	Single
Date of Defense:	14 December 2023
Subjects:	500 Science > 520 Astronomy
Institute / Center:	08 Faculty of Science > Institute of Astronomy
Depositing User:	Hammer Igor
Date Deposited:	08 Feb 2024 09:53
Last Modified:	08 Feb 2024 10:31
URI:	https://boristheses.unibe.ch/id/eprint/4865

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