GBAS Station SBAS Ephemeris Integration
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Solution Overview
Problem
Ground Based Augmentation Systems (GBAS) are susceptible to spatial decorrelation errors due to GPS satellite ephemeris faults, leading to potential loss of function and increased bounding errors, which impact continuity and availability requirements, especially when satellites are reintroduced or when GBAS stations are brought back online after downtime.
Innovation Solution
Integrating a Space Based Augmentation System (SBAS) receiver into the GBAS station to receive industry-standard messages containing SBAS ephemeris data, which improves error bounds and reduces the time required to reintroduce satellites and bring GBAS stations back online by using SBAS ephemeris standard deviations to compute and broadcast more accurate decorrelation parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GBAS stations use traditional ephemeris monitoring methods (FOH and MDM), then integrity monitoring is maintained, but satellites must be excluded for two days when faults occur, causing loss of function and large bounding errors
Solution Approach 1:
The patent introduces SBAS ephemeris data as an intermediary resource to resolve the conflict between integrity monitoring and satellite availability. When GBAS detects ephemeris faults, instead of immediately excluding satellites for two days, the system uses SBAS ephemeris data as a mediator to maintain continuous monitoring capability, allowing satellites to remain in service while integrity is preserved through the alternative data source.
Solution Approach 2:
The patent changes the parameter of ephemeris data source from purely ground-based (FOH/MDM) to a hybrid approach incorporating space-based SBAS data. This parameter change allows the system to maintain integrity monitoring while reducing the exclusion period for faulty satellites, thereby improving satellite availability and GBAS productivity.
2Measurement precision
If GBAS stations wait 24 hours for ephemeris buffers to fill before reintroducing satellites, then data accuracy is ensured, but time to restore full functionality is increased, impacting continuity requirements
Solution Approach 1:
The patent applies preliminary action by pre-fetching and storing SBAS ephemeris data in advance. When satellites need to be reintroduced, the system already has SBAS ephemeris data available, eliminating the need to wait 24 hours for ground-based ephemeris buffers to fill. This preliminary preparation reduces satellite reintroduction time while maintaining data accuracy through the pre-acquired SBAS data.
Solution Approach 2:
The patent uses SBAS ephemeris data as a copy or alternative source when ground-based ephemeris data is unavailable or insufficient. Instead of waiting for the primary ground-based buffer to fill, the system copies or substitutes SBAS ephemeris data to enable immediate satellite reintroduction, reducing the time loss while ensuring data accuracy through the validated SBAS source.
3Reliability
If GBAS stations exclude faulty satellites for two days, then spatial decorrelation errors are mitigated, but the number of available satellites decreases, increasing bounding errors and impacting continuity
Solution Approach 1:
The patent introduces SBAS ephemeris data as a mediator to resolve the conflict between mitigating spatial decorrelation errors and maintaining navigation solution accuracy. When satellites are excluded from ground-based monitoring, SBAS ephemeris data serves as an intermediary source that allows the system to maintain accurate navigation solutions without requiring the strict two-day exclusion period, thereby preserving satellite availability and solution precision.
Data Source
AI summary
A method of using space based augmentation system (SBAS) ephemeris data in conjunction with a ground based augmentation systems (GBAS) station is provided. The method includes integrating a space based augmentation system (SBAS) receiver in the GBAS station; receiving an industry-standard message type via the SBAS receiver at the GBAS station; consuming, at the GBAS station, the SBAS ephemeris data from the industry-standard message type associated with satellites in view of the GBAS station. The industry-standard message type includes SBAS ephemeris data associated with satellites in a global navigation satellite system (GNSS). The method further includes, based on the consuming, improving error bounds to GBAS broadcast ephemeris decorellation parameters broadcast from the GBAS station and reducing time to reintroduce a satellite in the GNSS.