Single Frequency GNSS Receiver Ionospheric Delay Compensation
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Solution Overview
Problem
Single frequency Global Navigation Satellite Systems (GNSS) receivers face significant ionospheric delay errors due to the dispersive nature of the ionosphere, which cannot be effectively corrected using conventional models, and dual frequency receivers are costly and complex.
Innovation Solution
A method and apparatus for a single frequency GNSS receiver that compensates for ionospheric delay by receiving signals from two satellites in different constellations, calculating ionospheric delay using the received signals, and canceling out Total Electron Content (TEC) values, allowing for accurate ionospheric delay compensation without the need for dual frequency receivers or complex modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dual frequency receivers are used to correct ionospheric delay, then positioning accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a third satellite as an intermediary to enable ionospheric delay correction. By using signals from three satellites (two at frequency f1 and one at frequency f2), the system can solve for ionospheric delay without requiring the receiver to process dual frequency signals from multiple satellites simultaneously, thus reducing receiver complexity while maintaining positioning accuracy
Solution Approach 2:
The patent creates a virtual dual-frequency observation by combining signals from three satellites. The ionospheric delay calculated from this combination is then applied as a correction to the primary frequency measurements, effectively copying the benefit of dual-frequency receivers without requiring full dual-frequency hardware
2Device complexity
If conventional ionospheric modeling is used in single frequency receivers, then device complexity is reduced, but positioning accuracy deteriorates due to inability to eliminate ionospheric delay
Solution Approach 1:
The system performs self-correction by using its own received signals from three satellites to calculate and eliminate ionospheric delay. Instead of relying on external modeling data or corrections, the receiver uses the signal combinations from the three satellites to derive and apply its own ionospheric delay correction, achieving high accuracy while maintaining single-frequency simplicity
Solution Approach 2:
The patent changes the approach from modeling ionospheric delay to directly calculating it from signal measurements. By forming specific linear combinations of carrier phase measurements from three satellites, the system transforms the uncorrectable ionospheric delay into a solvable parameter that can be eliminated from the positioning calculation
3Device complexity
If single frequency receivers are used, then device complexity and cost are reduced, but ionospheric delay error increases up to ten meters
Solution Approach 1:
The third satellite acts as an intermediary that enables the system to measure and correct ionospheric delay. By introducing this additional satellite into the calculation, the system can isolate and eliminate the ionospheric delay component that would otherwise cause up to ten meters of error in single-frequency receivers
Solution Approach 2:
The patent converts the harmful ionospheric delay effect into a useful measurement. By using the dispersive nature of the ionosphere across three satellites, the system transforms the delay error into a calculable parameter that, when removed, actually improves positioning accuracy beyond what would be possible without ionospheric effects
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
This approach enables effective ionospheric delay compensation in single frequency GNSS receivers, reducing errors and improving positioning accuracy without the complexity and cost associated with dual frequency systems or ionospheric modeling, by leveraging the proximity of satellites in different constellations to share common TEC values.
Implementation Method 1
The ionosphere is a dispersive medium, which lies between seventy and one thousand kilometers above the Earth's surface, and effects a certain, frequency dependent propagation delay on signals transmitted from GNSS satellites
Data Source
AI summary
Systems, methods, and apparatuses are provided for compensating for ionospheric delay in multi constellation Global Navigation Satellite Systems (GNSSs). In one method, a single Radio Frequency (RF) path receiver receives a first signal at a first frequency from a first satellite in a first GNSS constellation, receives a second signal at a second frequency from a second satellite in a second GNSS constellation, and calculates the ionospheric delay using the received first signal and the received second signal.