| Author: | Shao, Jingheng |
| Title: | Using dual-frequency SBAS in BDS-3 for UDRE optimization |
| Advisors: | Jiang, Yiping (AAE) |
| Degree: | M.Sc. |
| Year: | 2023 |
| Department: | Department of Mechanical Engineering |
| Pages: | x, 89 pages : color illustrations |
| Language: | English |
| Abstract: | Global Navigation Satellite Systems (GNSS) have found widespread applications in various fields, especially in the commercial aviation for its low-cost and continuous navigation. However, the precision of Global Navigation Satellite Systems (GNSS) can be significantly impacted by atmospheric delays and satellite errors. To improve the reliability and accessibility of GNSS, various augmentation systems have been developed, including the satellite-based augmentation system (SBAS). One of the key function for SBAS is to provide users with satellite ephemeris-clock (SEC) corrections, and generate corresponding confidence bound (UDRE/DFRE) to users, which serve as a means to evaluate the quality of the computed corrections. The initial phase of this research endeavor focuses on elucidating the basic theory of two SEC algorithms, namely WAAS and BDWAAS. A comprehensive comparison between these algorithms is conducted, examining their respective characteristics and performance. Furthermore, a static user location determination experiment was conducted to investigate the efficacy of the generated Satellite Ephemeris-Clock (SEC) corrections in the context of GPS-only positioning and GPS-BDS joint constellation positioning. The experimental findings reveal a substantial enhancement in positioning accuracy through the utilization of both WAAS and BDWAAS algorithms. Moreover, the SEC corrections generated based on WAAS and BDWAAS exhibit similar performance characteristics within a narrowly-distributed SBAS model, such as the HK region. The positioning enhancement is substantial, transitioning from meter-level to sub-meter level precision, with a particular emphasis on the GPS-BDS constellation. The second major contribution of this study is the development of a chi-square code carrier coherence (CCC) monitor aimed at detecting potential code carrier divergence (CCD), which would degrade the performance of computed satellite corrections. In this part of the study, we begin by analyzing the impact of CCD on the generation of satellite corrections. Additionally, we compare the characteristics of different CCC monitors and subsequently design an optimal chi-square monitor using an overbound technique. The results of the Probability of Missed Detection (PMD) analysis demonstrate that the proposed chi-square CCC monitor is capable of detecting smaller divergences while meeting the same integrity requirement across all 11 simulated divergence fault modes. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 7475.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 49.16 MB | Adobe PDF | View/Open |
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