GNSS Receiver Phase Measurement Bias Correction
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Solution Overview
Problem
Current GNSS signal processing techniques face challenges in achieving precise positioning due to biases and ambiguities in phase measurements, which are more accurate than pseudorange measurements but are affected by dispersive and nondispersive elements, phase windup, and multipath components.
Innovation Solution
A receiver system that receives at least three satellite signals with different frequencies, measures phase differences, and determines the contributions of dispersive elements, nondispersive elements, and phase windup to improve phase measurement accuracy by isolating and removing these components, allowing for more precise positioning and clock state determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase measurements are used instead of pseudorange measurements, then positioning accuracy is improved from meter-level to millimeter-level, but measurement biases and ambiguities increase due to dispersive elements, nondispersive elements, and phase windup
Solution Approach 1:
The patent segments the phase measurement into distinct components: dispersive elements (ionospheric effects), nondispersive elements (position, clock state, troposphere), and phase windup (rotational components). By measuring phase differences at multiple frequencies and mathematically separating these components, the invention resolves the measurement biases while preserving the millimeter-level accuracy advantage of phase measurements over pseudorange measurements
Solution Approach 2:
The patent utilizes multiple signal frequencies (L1, L2, and potentially L5) as varying parameters to differentiate between dispersive and nondispersive elements. By observing how phase measurements change across different frequencies, the system can isolate and remove ionospheric effects (which are frequency-dependent) from the positioning calculation, thereby reducing measurement bias complexity while maintaining high precision
2Measurement precision
If multiple frequency signals are processed to separate dispersive and nondispersive elements, then measurement accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the multi-frequency phase measurement data into distinct mathematical components representing different physical phenomena. By formulating separate equations for dispersive elements (ionosphere), nondispersive elements (geometry, clock, troposphere), and phase windup, the complex processing task is organized into manageable segments that can be solved systematically, reducing the perceived computational complexity
Solution Approach 2:
The patent performs preliminary processing by first measuring phase differences at multiple frequencies, then pre-calculating and removing known effects (such as modeled ionospheric delays and satellite antenna phase windup) before final position determination. This preliminary removal of known biases simplifies the subsequent computational steps and reduces overall processing complexity
Data Source
AI summary
Disclosed is a receiver that receives at least three satellite signals and determines the contribution of dispersive elements, nondispersive elements, and phase windup to a phase difference between each received satellite signal and a corresponding generated signal.