eLORAN Receiver Dynamic ASF Correction for Positioning Accuracy
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Solution Overview
Problem
Current eLORAN systems rely on fixed Additional Secondary Factor (ASF) maps that do not account for temporal and spatial variations in environmental conditions, leading to positioning discrepancies of hundreds of feet due to the use of a single ASF map for all times and seasons, which is inadequate for accurate navigation, especially in areas without reference stations.
Innovation Solution
An enhanced eLORAN system that includes a controller in eLORAN receivers to interpolate and correct receiver position and clock error using ASF data based on different geographical positions and times, with the ability to receive updated ASF data via wireless or eLORAN data channels, and stores multiple ASF correction curves to account for daily and seasonal variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single fixed ASF map is used for all times and seasons, then the system complexity is reduced and ease of operation is improved, but positioning precision deteriorates due to positioning discrepancies of hundreds of feet
Solution Approach 1:
The patent implements dynamic ASF correction by storing multiple ASF correction curves corresponding to different times of day and seasons, and selecting the appropriate curve based on current temporal conditions. This transforms the static ASF map into a dynamic correction system that adapts to environmental changes, resolving the contradiction between maintaining simplicity and achieving high positioning precision.
Solution Approach 2:
The patent changes the temporal parameters of ASF data by storing correction curves for different times and seasons, and selecting based on current time and season parameters. This parameter-based selection allows the system to maintain precision without requiring complex real-time environmental sensing, thus resolving the contradiction between precision and complexity.
2Measurement precision
If multiple ASF correction curves for different times and seasons are stored, then positioning precision is improved by reducing errors to tens of meters, but device complexity increases
Solution Approach 1:
The patent segments the ASF correction data into multiple curves corresponding to different times of day and seasons, organizing them in a structured manner. This segmentation allows efficient storage and retrieval of correction data without requiring excessive memory resources, resolving the contradiction between achieving high precision through multiple curves and managing data storage requirements.
3Reliability
If fixed ASF maps are used without temporal updates, then ease of operation is maintained, but reliability deteriorates due to inability to account for environmental variations
Solution Approach 1:
The patent performs preliminary action by pre-storing multiple ASF correction curves for different times and seasons in the receiver's memory before operation. This allows the system to reliably adapt to environmental variations without requiring complex real-time data updates or external connections, resolving the contradiction between improving reliability through temporal updates and maintaining operational simplicity.
Data Source
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AI summary
An enhanced LOng RAnge Navigation (eLORAN) system may include a plurality of eLORAN transmitter stations, and at least one eLORAN receiver device. The eLORAN receiver device may include an eLORAN receive antenna, an eLORAN receiver coupled to the eLORAN receive antenna, and a controller coupled to the eLORAN receiver. The controller may be configured to cooperate with the eLORAN transmitter stations to determine an eLORAN receiver position and receiver clock error corrected from additional secondary factor (ASF) data, the ASF data based upon different geographical positions and different times for each different geographical position.