GNSS Receiver Positioning Using Subset Carrier Phase Ambiguity Fixing
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Solution Overview
Problem
Existing GNSS receivers face challenges in accurately determining their absolute position in real-time due to errors in navigation signal transmission through the atmosphere and satellite biases, which are exacerbated by the need for dense reference station networks, leading to long convergence times for fixing carrier phase ambiguities.
Innovation Solution
A method that selects a subset of carrier phase measurements with lower error and fixes ambiguities only for this subset, using a recursive state estimator like a Kalman filter, while assigning floating values to measurements with higher errors, thereby reducing computational effort and convergence time without compromising precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all carrier phase measurements are used to fix ambiguities, then positioning precision is improved, but convergence time increases significantly
Solution Approach 1:
The patent segments the set of all carrier phase measurements into two subsets: a first subset with lower error characteristics and a second subset with higher error characteristics. By fixing ambiguities only for the first subset initially, the system achieves faster convergence while maintaining adequate positioning precision, resolving the contradiction between precision and convergence time.
Solution Approach 2:
The patent applies partial action by fixing ambiguities for only a portion (first subset) of the carrier phase measurements rather than all measurements. This partial fixing approach achieves sufficient positioning precision while significantly reducing the computational burden and convergence time compared to fixing all ambiguities.
2Measurement precision
If a dense reference station network is deployed, then positioning accuracy is improved, but system complexity and infrastructure requirements increase
Solution Approach 1:
The patent extracts and eliminates the dependency on dense reference station networks by using precise models to eliminate individual error components (satellite orbit errors, clock errors, biases, atmospheric delays) directly in the calculation. This extraction of the reference station requirement resolves the contradiction between achieving high positioning accuracy and reducing system complexity.
Solution Approach 2:
The system performs self-service by using precise models and algorithms to correct its own measurement errors without requiring external reference station infrastructure. The receiver independently eliminates error components through modeling, making the system self-sufficient and reducing infrastructure complexity.
3Measurement precision
If carrier phase ambiguity fixing is performed for all measurements, then positioning precision is improved, but computational effort increases
Solution Approach 1:
The patent segments carrier phase measurements into two subsets based on error characteristics. By fixing ambiguities only for the first subset with lower errors, the computational effort is significantly reduced while maintaining sufficient positioning precision, thus resolving the contradiction between precision and computational efficiency.
Solution Approach 2:
The patent applies partial action by performing ambiguity fixing only for a subset of measurements rather than all measurements. This partial fixing achieves adequate positioning precision while dramatically reducing the computational burden, improving overall productivity and processing efficiency.
Data Source
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AI summary
A method for determining a state parameter of a global navigation satellite system receiver and an apparatus, in particular its absolute position, determining being based on - a measured information including a pseudorange, a carrier phase and/or a Doppler frequency measurement, - broadcast information on the satellite orbits and clock offsets, and - high accuracy correction information of a satellite positions, clock offsets, code and/or phase biases, the method comprising: - determining a satellite position estimate and a clock offset estimate based on the broadcast information, - determining a corrected satellite position and a corrected clock offset based on the satellite position estimate and the clock offset estimate by using the high accuracy information, in particular the high accuracy correction information of the satellite position and the clock offset.