Variable Time-Horizon LTO Models for Satellite Accuracy
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Solution Overview
Problem
Current long-term orbit (LTO) models used by Assisted-GNSS receivers become less accurate over time, with worst-case satellite clock models being significantly incorrect after several days, leading to inaccuracies in position computation.
Innovation Solution
A method and apparatus that generate orbit parameter prediction models using variable time-horizons, comparing predicted parameters to current broadcast ephemeris to establish an accurate time-frame for each satellite, thereby improving accuracy by limiting the use of inaccurate models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If long term orbit models are used for extended periods into the future, then satellite availability is improved, but accuracy deteriorates significantly after several days
Solution Approach 1:
The patent implements dynamic time horizons that automatically adjust based on predicted accuracy levels. Instead of using a fixed time horizon for all satellites, the system calculates individual time horizons for each satellite based on their specific prediction accuracy, allowing the model to adapt to varying satellite performance characteristics and maintain optimal accuracy across different time periods
Solution Approach 2:
The patent applies different time horizon values to different satellites based on their individual prediction accuracy characteristics. Each satellite receives a customized time horizon rather than a uniform approach, allowing high-accuracy satellites to extend further into the future while limiting the time horizon for satellites that degrade faster, thus optimizing overall system accuracy
2Device complexity
If uniform time horizons are applied to all satellites, then system complexity is reduced, but overall accuracy deteriorates due to varying satellite performance
Solution Approach 1:
The patent changes the time horizon parameter dynamically based on prediction accuracy metrics. By adjusting this critical parameter according to measured accuracy levels, the system optimizes predictive performance without requiring complex manual intervention, allowing automatic adaptation to changing satellite conditions
3Productivity
If inaccurate LTO models are used, then satellite availability is maximized, but position computation accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where prediction accuracy is continuously monitored and used to adjust time horizons. This feedback loop ensures that only satellites meeting accuracy thresholds are included in the LTO model, automatically excluding degraded satellites while maintaining optimal accuracy for the selected subset
Data Source
AI summary
A method and apparatus for determining long term orbit (LTO) models using variable time-horizons to improve the orbit and clock model accuracy. The method and apparatus use either historic ephemeris or historic measurements for at least one satellite to produce an orbit parameter prediction model (an LTO model). The parameter predicted by the model is compared to an orbit parameter of a current broadcast ephemeris. The result of the comparison (an indicia of accuracy for the model) is used to establish a time-horizon for the orbit parameter prediction model for that particular satellite. Such a time-horizon may be established in this manner for each satellite within a satellite constellation.