Geometry-Free Combination Parameter for GNSS Scintillation Detection
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Solution Overview
Problem
Global Navigation Satellite Systems (GNSS) face challenges in accurately detecting and mitigating scintillations caused by ionospheric irregularities, which lead to signal fluctuations and positioning errors, especially in differential navigation modes where commercial receivers lack the capability to generate alerts for satellite usage.
Innovation Solution
A method involving the calculation of a geometry-free combination parameter based on GNSS measurements at different carrier frequencies to detect scintillations, allowing for the determination of ionospheric irregularities and subsequent mitigation strategies, such as using ionosphere-free combination parameters to reduce ionospheric biases in positioning calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dual-frequency carrier phase measurements are used to evaluate ionosphere delay, then ionosphere disturbance detection capability is improved, but device complexity increases and commercial applicability is limited
Solution Approach 1:
The patent introduces a geometry-free combination parameter as an intermediary that bridges dual-frequency measurements and scintillation detection. This parameter combines L1 and L2 carrier phase measurements in a specific way that eliminates geometric and clock errors, leaving only ionosphere-related terms. The intermediary transformation allows standard receivers to detect scintillations without requiring complex custom hardware modifications.
Solution Approach 2:
The patent replaces complex hardware-based detection mechanisms with software-based signal processing. Instead of requiring specialized hardware to detect ionosphere disturbances, the invention uses mathematical transformations of standard GNSS measurements to achieve the same detection capability, thereby reducing device complexity while maintaining measurement precision.
2Reliability
If threshold-based scintillation detection is implemented, then reliability of satellite selection is improved, but loss of information occurs when thresholds are not met
Solution Approach 1:
The patent implements feedback by continuously monitoring the geometry-free combination parameter and comparing it against threshold values. When the parameter exceeds the threshold, the system generates a scintillation alert and can exclude the affected satellite from positioning calculations. This feedback mechanism ensures reliable satellite selection while maintaining continuous information flow about ionosphere conditions.
Solution Approach 2:
The patent performs preliminary detection of scintillations using the geometry-free combination parameter before they severely impact positioning accuracy. By detecting ionosphere disturbances early through threshold comparison, the system can take preventive actions such as satellite exclusion or switching to alternative measurement combinations, thereby preventing information loss from undetected scintillations.
3Measurement precision
If geometry-free combination parameter is calculated from dual-frequency measurements, then detection accuracy of scintillations is improved, but use of energy increases
Solution Approach 1:
The patent applies partial action by calculating the geometry-free combination parameter only for satellites that are currently being tracked and used for positioning. Rather than processing all possible satellites continuously, the system focuses computational energy on relevant satellites, thereby improving detection accuracy for active satellites while reducing overall energy consumption compared to exhaustive processing of all satellites in view.
Data Source
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AI summary
A scintillation caused by ionospheric irregularities during Global Navigation Satellite System (GNSS) measurements is detected. A first input GNSS measurement corresponding to a navigation satellite and corresponding to a first carrier frequency and a second GNSS measurement corresponding to the navigation satellite and corresponding to a second carrier frequency, in which the second carrier frequency is different from the first carrier frequency, are received. A geometry-free combination (GFC) parameter based at least in part on the first input GNSS measurement, the second input GNSS measurement, the first carrier frequency, and the second carrier frequency is calculated. The occurrence of a scintillation caused by an ionospheric irregularity is determined based at least in part on the GFC parameter. In an embodiment of the invention, the dispersion of the GFC parameter over a specified time interval is determined. A scintillation is detected if the dispersion exceeds a specified threshold value.