Rover Station Virtual Reference Data for RTK Outages
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Solution Overview
Problem
Global Navigation Satellite Systems (GNSS) receivers face accuracy degradation during reference data outages due to errors such as satellite clock drifts, ionospheric, tropospheric, and orbit errors, leading to loss of centimeter-level positioning capability, which is critical for applications like surveying and precision agriculture.
Innovation Solution
The implementation of a position determination platform within the rover station that uses virtual reference data to maintain centimeter-level accuracy during reference data outages by mitigating error sources like satellite clock errors, ionospheric and tropospheric delays, and orbit errors, and resolving ambiguities through double-differenced observable equations and Kalman filter-based state estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Real-Time Kinematic (RTK) positioning is used to improve GNSS receiver accuracy, then positioning precision is improved, but the system becomes vulnerable to reference data outages that cause loss of centimeter-level accuracy
Solution Approach 1:
The system performs preliminary actions by continuously tracking satellite signals and maintaining ready-to-use measurements before reference data outages occur. When reference data becomes unavailable, the system can immediately switch to using previously collected satellite measurements and predictions, avoiding the need to restart positioning operations from scratch and maintaining service continuity.
Solution Approach 2:
The patent introduces an intermediary approach by using predicted satellite clock errors and orbital information as intermediate data sources when direct reference data from ground stations is unavailable. This intermediary data allows the system to bridge the gap during reference data outages, maintaining positioning accuracy without requiring continuous real-time reference data connection.
2Measurement precision
If continuous reference data transmission is required to maintain RTK accuracy, then positioning precision is maintained, but system complexity and dependency on continuous communication increases
Solution Approach 1:
The system implements self-service by using its own tracked satellite measurements and predictions to maintain positioning accuracy during reference data outages. Instead of requiring continuous external reference data, the system can autonomously compute corrections using its collected data and predictive models, reducing dependency on continuous communication infrastructure and simplifying system architecture.
Solution Approach 2:
The patent applies parameter changes by switching between different data sources and processing modes based on reference data availability. When reference data is available, the system uses standard RTK processing; when unavailable, it transitions to using predicted parameters and previously tracked measurements, allowing the system to maintain accuracy across varying operational conditions without requiring complex continuous communication protocols.
3Reliability
If reference data outages are tolerated, then system robustness is improved, but positioning accuracy degrades during outages
Solution Approach 1:
The system prepares beforehand by continuously tracking satellite signals and maintaining a buffer of recent measurements even when reference data is available. This cushioning approach ensures that when reference data outages occur, the system has sufficient historical data and predictions to maintain accurate positioning, preventing accuracy degradation during outages while maintaining operational robustness.
Data Source
AI summary
A method includes processing reference data and positioning signals to determine a first position of a rover station for a first instance in time. A first pseudo-range measurement of a frequency and a first carrier phase measurement of the frequency are calculated. The method also includes detecting an inability to receive the reference data and generating virtual reference data based on the reference data, the position of the rover station, the first pseudo-range measurement, and the first carrier phase measurement. A second pseudo-range measurement of the frequency and a second carrier phase measurement of the frequency are calculated. The method further includes processing the virtual reference data, the positioning signals, the second pseudo-range measurement and the second carrier phase measurement, based on the detected inability to receive the reference data, to determine a second position of the rover station for a second instance in time.