GNSS RTK Buffering Across Epochs for Multipath-Robust Positioning
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Solution Overview
Problem
Existing GNSS systems face challenges in achieving accurate real-time positioning, particularly in dynamic environments, due to multipath errors caused by signal reflections, which affect both pseudo-range and carrier phase measurements.
Innovation Solution
The implementation of an enhanced RTK mode in GNSS devices, which involves storing GNSS data in a buffer and using it for batch processing, allowing for real-time kinematic calculations based on multiple epochs of data, including carrier phase and pseudo-range measurements, to improve positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time kinematic calculations are performed using only current epoch data, then processing speed is maintained, but positioning accuracy deteriorates due to multipath errors
Solution Approach 1:
The system performs preliminary actions by storing GNSS data from multiple past epochs in a buffer before the current epoch arrives. This allows the RTK engine to access historical data (epochs -1, -2, -3) in addition to current data (epoch 0) when performing kinematic calculations, enabling the use of more data points to improve positioning accuracy while maintaining real-time processing capability.
2Measurement precision
If multiple epochs of GNSS data are stored and processed, then positioning accuracy improves, but memory usage and processing complexity increase
Solution Approach 1:
The system segments the GNSS data stream into distinct epochs and stores only a limited number of recent epochs (typically 3-5 epochs) in a buffer. Each epoch is treated as a separate data unit, allowing the RTK engine to selectively process specific epochs (0, -1, -2, -3) rather than storing and processing all historical data, thus managing memory usage efficiently while maintaining accuracy.
3Reliability
If batch processing of multiple epochs is performed, then robustness against multipath errors improves, but real-time processing capability deteriorates
Solution Approach 1:
The system implements periodic action by processing GNSS data in discrete epoch intervals rather than continuous batch processing. The RTK engine periodically accesses the buffer to retrieve data from epochs 0, -1, -2, -3 and performs kinematic calculations at each epoch boundary. This periodic processing maintains real-time capability while incorporating multiple epochs to improve robustness against multipath errors.
Data Source
AI summary
An exemplary method of calculating a position of a GNSS device (e.g., a GNSS rover device) comprises: at the GNSS device in an enhanced real-time kinematic (RTK) mode: receiving a first set of GNSS data corresponding to a first epoch; storing the first set of GNSS data in a buffer; receiving a second set of GNSS data corresponding to a second epoch that is after the first epoch; after receiving the second set of GNSS data, retrieving the first set of GNSS data from the buffer; and calculating the position of the GNSS device based on the retrieved first set of GNSS data and the second set of GNSS data.