Ionosphere Grid Compression for GNSS Positioning Accuracy
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Solution Overview
Problem
Existing GNSS positioning systems face accuracy degradation due to ionospheric delay errors, which are challenging to correct in real-time, especially in environments with weak or blocked satellite signals.
Innovation Solution
The use of historical ionospheric delay information, in combination with current data, to estimate ionospheric delay, along with the compression of ionosphere grid products using spherical harmonic functions, to reduce data transmission and storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time ionospheric delay correction data is transmitted frequently to improve positioning accuracy, then measurement precision improves, but bandwidth consumption increases
Solution Approach 1:
The system performs preliminary compression of ionospheric grid products using spherical harmonic functions before transmission. By pre-processing the data into a compressed mathematical representation, the system reduces the bandwidth required for transmission while maintaining the capability to provide accurate real-time correction values when needed.
Solution Approach 2:
The system changes the representation parameters of ionospheric data by transforming spatial grid data into spherical harmonic coefficients. This parameter transformation compresses the data structure, reducing transmission bandwidth requirements while preserving the essential information needed for delay correction calculations.
2Measurement precision
If high-resolution ionosphere grid products are stored to improve correction accuracy, then measurement precision improves, but memory requirements increase
Solution Approach 1:
The system applies spherical harmonic transformation to convert high-resolution spatial grid data into a compact coefficient representation. This parameter change maintains the ability to achieve high correction accuracy while dramatically reducing the memory storage required, as the spherical harmonic coefficients occupy significantly less space than the original grid data.
3Reliability
If augmentation data is transmitted via satellite to improve availability, then system reliability improves, but data transmission speed decreases
Solution Approach 1:
The system pre-compresses ionospheric grid products into spherical harmonic representations before satellite transmission. This preliminary compression reduces the data volume that must be transmitted via satellite, thereby increasing transmission speed while maintaining the reliability benefits of satellite-based augmentation data delivery.
Data Source
AI summary
Described are methods, systems, and devices for correcting ionospheric error. In some aspects, a mobile device equipped with a Global Navigation Satellite System (GNSS) receiver is configured to determine a positioning measurement of a GNSS signal. The mobile device is further configured to receive augmentation data from an augmentation system. When the mobile device is unable to obtain newer augmentation data, the mobile device can instead obtain augmentation data associated with historical Total Electron Content (TEC) values. In such instances, the augmentation data will have been generated to represent ionospheric delay during a time period that ended before the augmentation data is obtained. Based on the augmentation data associated with historical TEC values and a pierce point of the received GNSS signal, an ionospheric error in the positioning measurement of the GNSS signal can be determined and corrected.