GNSS Outlier Detection via Duplicate Filter Segmentation
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Solution Overview
Problem
Current satellite positioning systems face challenges in accurately detecting outliers in GNSS observations, which can disrupt carrier phase ambiguity resolution and require a minimum number of satellites for reliable updates, limiting their performance, especially in low-quality or sparse satellite environments.
Innovation Solution
The system employs a duplicate filter to detect outliers independently of the primary filter, allowing for improved outlier detection and mitigation without disturbing ambiguity states, enabling updates with fewer satellites and higher outlier fractions, thereby enhancing accuracy and availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a primary filter is used to detect outliers in GNSS observations, then outlier detection can be performed, but the ambiguity states are disturbed and a minimum number of satellites is required for reliable updates
Solution Approach 1:
The system divides the filter into two independent instances: a primary filter for maintaining ambiguity states and a duplicate filter for outlier detection. This segmentation allows outlier detection functionality to be separated from the ambiguity resolution process, enabling outlier detection without disturbing the ambiguity states in the primary filter.
Solution Approach 2:
A duplicate filter is created as a copy of the primary filter specifically for outlier detection purposes. The duplicate filter receives the same GNSS observations and produces outlier detection results without affecting the primary filter's ambiguity states. This copying approach enables independent outlier detection while preserving the integrity of the primary positioning solution.
2Reliability
If a minimum number of satellites is required for outlier detection updates, then reliability is maintained, but system availability decreases in sparse satellite environments
Solution Approach 1:
The system applies partial action by using only the subset of satellite observations that are available and reliable for outlier detection in the duplicate filter, rather than requiring a fixed minimum number. This allows the outlier detection to function with fewer satellites when necessary, improving availability in sparse environments while maintaining reliability through the use of available quality observations.
3Measurement precision
If outlier detection is performed in the primary filter, then outlier detection accuracy is improved, but the ambiguity states are disturbed and carrier phase ambiguity resolution is disrupted
Solution Approach 1:
The filter functionality is segmented into distinct roles: the primary filter focuses exclusively on maintaining ambiguity states and generating positioning solutions, while the duplicate filter handles outlier detection. This segmentation eliminates the conflict between outlier detection and ambiguity resolution, allowing both functions to operate optimally without interfering with each other.
Solution Approach 2:
The duplicate filter acts as an intermediary component that processes GNSS observations for outlier detection and feeds results back to the primary filter or positioning solution, without directly modifying the primary filter's internal states. This intermediary approach enables outlier detection accuracy improvement while preserving the primary filter's ambiguity resolution efficiency.
Data Source
AI summary
An system and/or method for detecting outliers in satellite observations can include: receiving satellite observations associated with one or more satellite constellations; receiving sensor data; determining a GNSS positioning solution using a filter to process the satellite observations; determining a fused positioning solution; detecting whether outliers are present in the satellite observations; and when outliers are detected, updating the GNSS positioning solution and/or the fused positioning solution using a set of outlier mitigated satellite observations.