Pre-computed Coefficients for Real-time Navigation Protection Levels
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Solution Overview
Problem
Current methods for determining protection levels of navigation solutions, such as ARAIM, require significant computational resources due to the lack of an analytical solution and costly mathematical functions, making it difficult to implement in receivers with limited computing capacities in real-time, especially in multi-constellation contexts.
Innovation Solution
A method that includes a preliminary phase to compute and store coefficients using the reverse function of the Gaussian distribution, allowing for real-time determination of protection levels in a multi-constellation context by using these coefficients in an integrity relationship to calculate protection levels efficiently, even in receivers with limited computing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ARAIM method is used to determine protection levels from redundant information obtained from satellites visible from several constellations, then the availability of aeronautic receivers is improved, but the computation capacity required becomes excessively large for real-time implementation
Solution Approach 1:
The patent pre-computes and stores integrity values and protection levels during an initialization phase before real-time operation. During runtime, the receiver only needs to retrieve pre-computed coefficients and perform simple linear combinations, avoiding the need to solve the integrity relationship numerically in real-time. This preliminary action enables real-time protection level determination with limited computation capacity while maintaining ARAIM's multi-constellation reliability benefits
2Measurement precision
If the integrity relationship is numerically resolved for each navigation solution to determine protection levels, then accurate protection levels are obtained, but the computation time becomes too long for real-time implementation
Solution Approach 1:
The patent pre-computes integrity values and protection levels during an initialization phase, storing them as coefficients. During real-time operation, these pre-computed coefficients are retrieved and combined linearly with current measurement data to determine protection levels instantly. This eliminates the need for time-consuming numerical resolution of the integrity relationship during each navigation solution update while preserving accuracy
Solution Approach 2:
The patent creates a simplified computational model by copying the structure of the integrity relationship into a pre-computed coefficient table. Instead of solving the complex integrity relationship numerically each time, the system uses pre-computed copies of the relationship results (integrity values and protection levels) that can be quickly retrieved and combined with current measurements
Data Source
AI summary
A method for determining protection levels that comprises a preliminary phase carried out at least one time and a main phase carried out upon determining each new navigation solution. The preliminary phase comprises the steps of acquiring a first error value, providing a set of numbers of monitored faults, determining a plurality of computation coefficients, and storing the set of determined computation coefficients. The main phase includes the steps of determining a current number of monitored faults, and determining a protection level of the corresponding navigation solution by using an integrity relationship and the computation coefficients determined during the preliminary phase.