Calibrating Vehicle-Mounted GNSS Antenna Group Delay
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Solution Overview
Problem
Vehicle-mounted GNSS antennas experience systematic group delay variations due to their mounting location and the vehicle's body, which affect positioning accuracy and integrity.
Innovation Solution
A method of calibrating vehicle-mounted GNSS antennas by measuring their response at various angles and calculating group delay variations, allowing for correction of these variations to improve positioning accuracy and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a low-cost GNSS antenna is mounted directly to the vehicle body panel, then cost efficiency and vehicle design integration are improved, but systematic group delay variations occur that affect positioning accuracy
Solution Approach 1:
The patent applies preliminary action by performing antenna calibration before actual GNSS operation. The system pre-characterizes the antenna's group delay variations across different angular dimensions when mounted on the vehicle, storing this calibration data for later use during positioning operations to correct the systematic errors.
Solution Approach 2:
The patent changes parameters by measuring and characterizing group delay variations across multiple angular dimensions (azimuth and elevation angles). The calibration process captures how group delay changes with direction, creating a multi-dimensional parameter set that is used to correct positioning calculations and compensate for the mounting-induced errors.
2Volume of moving object
If a low-cost GNSS antenna is mounted directly to the vehicle body panel, then the need for larger antenna structures is avoided, but group delay variation characterization becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the calibration process into discrete angular measurements. The system measures group delay at multiple azimuth angles and multiple elevation angles separately, creating a segmented angular grid. This segmentation makes the complex calibration process systematic and manageable, allowing the antenna response to be characterized in two-dimensional angular steps.
Solution Approach 2:
The patent transitions to another dimension by adding angular dimensionality to the calibration process. Instead of single-point measurements, the system characterizes group delay across two angular dimensions (azimuth and elevation), creating a comprehensive spatial map of antenna performance that accounts for the three-dimensional mounting environment on the vehicle.
Data Source
AI summary
A method is provided for calibrating a vehicle mounted GNSS antenna. The method comprises measuring a response of the antenna, while the antenna is mounted on the vehicle. Based on the measured response, data characterizing a group delay variation of the antenna is calculated. The data may be used to correct ranging measurements derived from GNSS signals received via the vehicle-mounted antenna. Alternatively, or in addition, the data may be used in estimating the integrity of a position fix.