Mitigating GNSS Scintillations via Geometry-Free Combinations
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Solution Overview
Problem
Global Navigation Satellite Systems (GNSS) are affected by ionospheric irregularities, leading to scintillations that cause signal delays and scattering, resulting in positioning accuracy degradation and potential loss of signals.
Innovation Solution
A method to detect and mitigate scintillations by calculating a geometry-free combination parameter from GNSS measurements at different carrier frequencies, generating a scintillation indicator, and using ionosphere-free combination parameters to correct for ionospheric effects, thereby improving positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS signals are received through the ionosphere, then positioning functionality is enabled, but scintillations caused by ionospheric irregularities degrade positioning accuracy and cause signal loss
Solution Approach 1:
The patent applies parameter changes by forming geometry-free combinations of GNSS observations at different frequencies to eliminate ionospheric effects. Specifically, it uses linear combinations of carrier phase and code measurements at multiple frequencies (e.g., L1, L2, L5) where the ionospheric delay terms cancel out, transforming the measurements into parameters that are insensitive to ionospheric scintillations
Solution Approach 2:
The patent introduces an intermediary detection mechanism that monitors geometry-free combination parameters to detect scintillation events. This intermediary parameter serves as an indicator that triggers the switching between standard processing and scintillation-mitigated processing modes
2Reliability
If standard GNSS processing is used, then computational simplicity is maintained, but positioning accuracy degrades during scintillation events
Solution Approach 1:
The patent implements partial action by applying scintillation mitigation only when and where needed - specifically when scintillation detection indicators are triggered. The system processes geometry-free combination parameters and applies corrections selectively to affected satellites and time periods, rather than continuously processing all data through complex mitigation algorithms
Solution Approach 2:
The patent segments the GNSS signal processing into distinct components: standard processing for normal conditions and scintillation-mitigated processing for affected conditions. It divides the observations into geometry-free combinations that isolate ionospheric effects, allowing independent detection and correction without reprocessing the entire measurement set
3Measurement precision
If multi-frequency GNSS measurements are processed, then ionospheric effects can be mitigated, but measurement and processing complexity increases
Solution Approach 1:
The patent merges multiple frequency measurements into geometry-free combination parameters that consolidate ionospheric information. By combining carrier phase and code measurements at different frequencies into unified geometry-free parameters, it reduces the dimensionality of the problem while preserving the essential ionospheric effects for detection and mitigation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively detects scintillations and mitigates their impact on GNSS signals, enhancing positioning accuracy and reliability by accounting for ionospheric influences.
Implementation Method 1
scintillations in signals of global navigation satellite systems caused by ionospheric irregularities
Implementation Method 2
leading to scintillations that cause signal delays and scattering
Implementation Method 3
Each input GNSS measurement in the plurality of input GNSS measurements is related to a corresponding navigation satellite in a plurality of navigation satellites and is made at a corresponding carrier frequency in a plurality of carrier frequencies
Implementation Method 4
using ionosphere-free combination parameters to correct for ionospheric effects
Data Source
AI summary
Scintillations caused by ionospheric irregularities during Global Navigation Satellite System (GNSS) measurements are detected and mitigated. Detection is based at least in part on statistical properties of geometry-free combination parameters calculated from input GNSS measurements corresponding to the same navigation satellite and different carrier frequencies. Mitigation is based at least in part on ionosphere-free combination parameters calculated from input GNSS measurements corresponding to the same navigation satellite and different carrier frequencies. Depending on the number of satellites with detected scintillations, different algorithms are used to calculate values of target parameters from a set of ionosphere-free combination parameters or from a set of ionosphere-free combination parameters and the remaining input GNSS measurements. Different algorithms accommodate stand-alone mode code phase measurements, stand-alone mode carrier phase measurements, differential navigation mode code phase measurements, and differential navigation mode carrier phase measurements.