GNSS Ambiguity Estimation Bias Correction
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Solution Overview
Problem
Existing methods for estimating integer carrier ambiguities in GNSS positioning systems are inefficient and prone to bias, particularly during convergence, due to the simultaneous estimation of ionosphere parameters, leading to long convergence times and inaccurate results.
Innovation Solution
The method iteratively solves for observation vectors from GNSS receivers, separating ionosphere-like biases from float ambiguities using fixed wide-lane integer ambiguities, allowing for reliable estimation of real-valued ambiguities and improving processing efficiency by correcting biases step-wise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If integer carrier ambiguities are estimated simultaneously with ionosphere parameters, then a complete positioning solution is obtained, but the estimated float ambiguities become biased and convergence time increases
Solution Approach 1:
The patent segments the estimation process into distinct steps: first estimating float ambiguities separately from ionosphere parameters, then using fixed wide-lane integer ambiguities to identify and remove ionosphere-like biases, and finally obtaining corrected float ambiguities. This segmentation eliminates the bias that occurs when estimating both simultaneously, resolving the contradiction between reliability and convergence time.
Solution Approach 2:
The patent extracts and isolates the ionosphere-like biases from the float ambiguity estimates by using fixed wide-lane integer ambiguities as a reference. By taking out this bias component, the method obtains corrected float ambiguities that are not contaminated by ionospheric effects, thereby improving accuracy without requiring simultaneous estimation that would increase convergence time.
2Device complexity
If float ambiguities are estimated without separating ionosphere biases, then processing is simpler, but the results are biased and inaccurate
Solution Approach 1:
The patent introduces fixed wide-lane integer ambiguities as an intermediary tool to identify and remove ionosphere-like biases from float ambiguity estimates. This intermediary element enables the separation of biases without requiring complex simultaneous estimation procedures, thus improving measurement precision while maintaining relatively simple processing.
3Productivity
If simultaneous estimation of ambiguities and ionosphere parameters is used, then all parameters are solved together, but processing demands increase and accuracy decreases
Solution Approach 1:
The patent segments the parameter estimation into separate stages: first obtaining float ambiguities, then using fixed wide-lane integer ambiguities to identify ionosphere-like biases, and finally correcting the float ambiguities. This segmentation reduces processing demands compared to simultaneous estimation while improving accuracy by eliminating bias contamination.
Solution Approach 2:
The patent performs preliminary estimation of float ambiguities before addressing ionosphere biases. By using fixed wide-lane integer ambiguities to identify biases in advance, the method prepares corrected ambiguity values that can be used in subsequent processing, improving both efficiency and accuracy.
Data Source
AI summary
Method for precise GNSS positioning system with improved ambiguity estimation. The method is based on the realization that, especially during convergence, the estimated float ambiguities are biased when estimated simultaneously with the ionosphere parameters. The “ionosphere-like” biases can be separated from the actual float ambiguities by using the fixed wide-lane (or extra wide-lane) integer ambiguities. The original real-valued ambiguities (e.g., one of L1, L2 and L5 in the GPS case) are corrected using the corresponding biases, resulting in reliable float ambiguities that are taken as input in the next processing step.