Satellite Navigation Protection Level Determination
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Solution Overview
Problem
Current satellite navigation systems lack the ability to effectively manage varying integrity risks across different flight phases and do not provide optimal solutions for alert limits larger than the smallest set, failing to meet diverse integrity requirements for flight safety.
Innovation Solution
A method and apparatus that determine protection levels by calculating integrity risk at various alert limits, using interval nesting to divide horizontal and vertical integrity risks, allowing for conservative alert limits without requiring knowledge of the current flight phase, and enabling the use of better processors to determine smaller alert limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the system uses a fixed set of alert limits, then the integrity risk management is simplified, but the system cannot meet diverse integrity requirements for different flight phases
Solution Approach 1:
The patent segments the integrity risk management into multiple discrete alert limit sets, each corresponding to specific flight phases (oceanic, en-route, terminal, approach, landing). This segmentation allows the system to provide different integrity levels for different operational contexts without requiring complex real-time assessment of flight phase, thereby achieving adaptability while maintaining manageable system complexity.
2Ease of operation
If the system determines protection levels without knowing the current flight phase, then the system operation is simplified, but the integrity risk determination may not be optimal for all flight phases
Solution Approach 1:
The patent creates a universal integrity risk determination method that works across all flight phases without requiring flight phase identification. The system uses a unified approach with multiple alert limit sets that can be applied universally, allowing the same determination logic to serve multiple flight phases effectively, thus achieving both operational simplicity and adequate precision.
3Reliability
If the system uses the smallest set of alert limits, then the integrity risk is minimized, but the system cannot provide optimal solutions for larger alert limits
Solution Approach 1:
The patent implements a dynamic alert limit selection mechanism where the system can adaptively choose among multiple alert limit sets based on operational requirements. This dynamic approach allows the system to use the smallest alert limits (providing minimum integrity risk) when highest reliability is needed, while also being capable of using larger alert limits when appropriate for the operational context, thus achieving both reliability minimization and versatility.
Data Source
AI summary
A method and apparatus for determining protection levels in a satellite navigation system includes the following steps: (1) determining an integrity risk at the alert limit for a plurality of application situations—for example, starting from approaches in category I (Category I precision approach) up to the operation “oceanic enroute;” (2) determining an interval of the alert limits between the largest set of alert limits which produces too high an integrity risk, and the smallest set of alert limits which produces an acceptable integrity risk; and (3) carrying out an interval nesting for the interval of the alert limits that was determined in the previous step, the integrity risk between the horizontal and the vertical being divided in the same way as it is obtained from the relationship between these integrity risks in the largest set of alert limits.