GBAS SBAS Navigation Data Update Notification Mechanism
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Solution Overview
Problem
The existing Ground Based Augmentation System (GBAS) for aircraft navigation faces a deterioration in positioning accuracy due to the use of different SBAS navigation data in the ground and airborne systems, which can compromise safety as the data used for correction purposes is not synchronized.
Innovation Solution
An SBAS navigation data update notifying system is implemented within the GBAS, where the ground system estimates errors in ranging signals, formats correction information, and notifies the airborne system of data updates, ensuring that both systems use consistent SBAS navigation data by adding update information to the correction data and detecting updates to switch to the latest navigation data for precise differential GPS positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the IOD field is set to 1 (1111 1111) for SBAS satellites as per SARPs definition, then the system follows international standards, but the airborne system cannot specify the SBAS navigation data used by the ground system
Solution Approach 1:
The patent introduces an intermediary mechanism by modifying the IOD field structure to include both the original SARPs-compliant value (1 for SBAS satellites) and additional navigation data version information. This intermediary approach allows the system to maintain standard compliance while simultaneously transmitting the necessary version information to the airborne system.
Solution Approach 2:
The patent embeds additional navigation data version information within the existing IOD field structure. By nesting the version information inside the IOD field that already exists in the GBAS Type 1 data structure, the system can convey extra information without adding separate fields or disrupting the standard format.
2Adaptability or versatility
If the ground system and airborne system use different SBAS navigation data, then each system can independently update their data, but the positioning accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the ground system includes navigation data version information in the GBAS Type 1 data transmitted to the airborne system. The airborne system uses this feedback information to determine whether to update its navigation data, ensuring that both systems use the same data version for differential GPS calculations.
Solution Approach 2:
The patent applies preliminary action by having the ground system prepare and transmit navigation data version information along with the correction data. This allows the airborne system to proactively check for version mismatches before performing differential GPS calculations, preventing accuracy deterioration caused by using different data versions.
3Device complexity
If the IOD field uses the standard SARPs definition with value 1 for SBAS satellites, then the data format remains simple and standardized, but the airborne system cannot detect when SBAS navigation data updates occur
Solution Approach 1:
The patent changes the parameter representation in the IOD field by encoding navigation data version information within the field's structure. This allows the field to maintain its original format and position in the data structure (preserving simplicity) while containing additional information that enables the airborne system to detect SBAS navigation data updates.
Data Source
AI summary
To maintain the safety by avoiding deterioration in the positioning accuracy through making SBAS satellite navigation data used in a ground system and in an airborne system consistent by employing GBAS. The system includes: a ground system which estimates errors contained in ranging signals received from the navigation satellites, and formats and transmits correction information for correcting the estimated errors; and an airborne system which calculates differential GPS positioning based on the ranging signals received from the navigation satellites and the formatted correction information, and displays a displacement from a regulated route. The ground system notifies update, when SBAS satellite navigation data used for generating the correction information is updated, by adding information regarding update of navigation data to the correction information. The airborne system detects the transmitted update notification of the SBAS satellite navigation data, and calculates the differential GPS positioning by switching to the updated navigation data.