GBAS Ionosphere Error Mitigation via SBAS GIVE Data
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ground Based Augmentation Systems (GBAS) face accuracy issues due to ionospheric gradients, which can cause significant position errors in aircraft navigation, especially during precision approaches, as the ionosphere's non-uniformity leads to spatially decorrelated errors between the GBAS station and the aircraft's GNSS receiver.
Innovation Solution
The integration of Space-Based Augmentation System (SBAS) data allows for real-time monitoring of ionospheric conditions, enabling the selection of appropriate mitigation techniques, such as geometry screening and overbounding of Vertical Ionosphere Gradient standard deviation, to ensure accurate navigation by identifying and mitigating potential ionospheric threats, thereby improving the availability and integrity of GBAS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GBAS uses traditional ionospheric mitigation methods, then system complexity remains manageable, but position accuracy deteriorates under ionospheric gradient conditions
Solution Approach 1:
The patent introduces SBAS GIVE data as an intermediary information source that bridges the gap between GBAS ground station measurements and aircraft receiver calculations. This external ionospheric error data from a different spatial location (SBAS coverage area) serves as a mediator to improve GBAS position accuracy without requiring complex modifications to the core GBAS architecture.
Solution Approach 2:
The patent makes the GBAS ground subsystem multi-functional by enabling it to not only process traditional GBAS pseudorange corrections but also to receive, process, and utilize SBAS GIVE ionospheric error data. This allows a single ground subsystem to serve multiple augmentation functions, improving position accuracy across different operational scenarios without proportionally increasing complexity.
2Reliability
If GBAS implements comprehensive ionospheric monitoring and mitigation, then reliability improves, but device complexity increases
Solution Approach 1:
The patent merges the GBAS ground subsystem with SBAS ionospheric data processing capabilities. By combining these functions into a single integrated ground subsystem, the patent improves reliability through comprehensive ionospheric monitoring while avoiding the complexity increase that would result from completely separate systems. The merged subsystem efficiently handles both traditional GBAS corrections and SBAS GIVE data.
Solution Approach 2:
The patent implements feedback mechanisms where the ground subsystem continuously monitors ionospheric conditions using SBAS GIVE data and adjusts its correction outputs accordingly. This feedback loop enables the system to dynamically respond to changing ionospheric conditions, improving reliability by ensuring accurate corrections are provided when ionospheric gradients are present, while maintaining manageable complexity through automated decision-making algorithms.
3Reliability
If GBAS applies strict ionospheric error bounds, then integrity is improved, but availability decreases
Solution Approach 1:
The patent applies dynamic error bounding where the Vertical Ionosphere Gradient (VIG) standard deviation is adjusted in real-time based on SBAS GIVE data quality and ionospheric conditions. During periods of high ionospheric activity or poor SBAS data quality, stricter bounds are applied to maintain integrity. During stable conditions with high-quality SBAS data, the bounds are relaxed to improve availability. This dynamic approach resolves the contradiction between maintaining strict integrity bounds and preserving system availability.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
GBAS includes reference receivers, processing module, and communication device. Processing module checksGNSS satellite measurements to determine proximity of GNSS satellite measurement's IPP to IGPs derived from SBAS geostationary satellites. Processing module determines that GNSS satellite measurement is safe for mitigation using overboundedVertical Ionosphere Gradient standard deviation sigma-vig (σvig) when IGPs possess acceptable GIVE values. Processing module determines whether number of GNSS satellite measurements determined safe for mitigation using σvig are able to produce VPL that meets VAL required for precision approach. Communication device communicatesoverboundedσvig along with differential corrections and indication of which GNSS satellite measurements that are safe for mitigation using at least one overboundedσvig are able to produce VPL that meets VAL required for precision approach to GNSS receiver when number of GNSS satellite measurements determined safe for mitigation using overboundedσvig are able to produce VPL that meets VAL required for precision approach.