Antenna Sensor Bias Calibration via Phase Difference
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Solution Overview
Problem
Current antenna calibration methods for satellite radionavigation receivers are costly and unable to account for sensor aging, leading to variability in bias values that affect signal processing performance.
Innovation Solution
A method for calibrating antenna sensors by measuring phase shifts and determining biases using a least squares approach, which accounts for antenna attitude and sensor aging, allowing for in-flight calibration and periodic updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If factory calibration is performed to determine sensor biases, then initial measurement precision is improved, but production cost increases and sensor aging variability cannot be compensated
Solution Approach 1:
The patent performs preliminary calibration actions during the factory production phase to establish initial sensor bias values. These preliminary calibration results are stored and used as reference data, allowing the system to operate with acceptable precision initially while avoiding the need for continuous expensive recalibration procedures.
Solution Approach 2:
The system implements self-calibration capabilities where the receiver automatically determines sensor biases using satellite signal measurements during operation. The calibration algorithm uses the known satellite positions and measured signal phases to compute bias corrections without external intervention, enabling the system to maintain and update its own calibration status throughout its operational life.
2Measurement precision
If factory calibration is performed to determine sensor biases, then initial measurement precision is improved, but the system cannot adapt to sensor aging over time
Solution Approach 1:
The patent transitions from static factory calibration to dynamic in-flight calibration, where sensor bias values are continuously updated based on current operational conditions. The system adapts to sensor aging by periodically recalibrating using satellite signal measurements, ensuring that calibration data remains accurate throughout the sensor's operational lifetime rather than becoming obsolete over time.
Solution Approach 2:
The system implements feedback mechanisms where measured satellite signal phases are compared with expected phases based on known satellite positions. The difference (residual) provides feedback that is used to update and refine sensor bias estimates, creating a closed-loop system that continuously adapts to changing sensor characteristics due to aging or environmental factors.
3Adaptability or versatility
If in-flight self-calibration device is added to determine sensor biases, then adaptability to sensor aging is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the existing satellite signal reception system perform the dual function of both navigation and calibration. The same antenna and signal processing chains used for receiving navigation signals are also utilized to measure phase differences for bias determination. This eliminates the need for separate calibration hardware, as the navigation infrastructure itself serves the calibration function.
Solution Approach 2:
The system performs self-calibration using its own operational signals without requiring external calibration equipment or test signals. The calibration process leverages the natural satellite signals already being received for navigation, processing them through the existing signal chain to extract bias information, thereby avoiding additional hardware complexity.
4Measurement precision
If traditional calibration methods are used to eliminate antenna sensor biases, then measurement precision is improved, but the method cannot account for bias variability independent of satellite directions
Solution Approach 1:
The patent segments the total sensor bias into two distinct components: a directional component that varies with satellite position and a direction-independent component that remains constant regardless of satellite direction. This segmentation allows different calibration strategies to be applied to each component, with the direction-independent bias being determined through in-flight calibration and used to correct all measurements uniformly.
Solution Approach 2:
The patent changes the calibration approach from eliminating biases through double differencing to directly determining and correcting bias values. By measuring phase shifts across multiple sensors and satellites, the system solves for sensor-specific bias parameters that can then be applied as corrections, transitioning from a differential elimination approach to a direct parameter estimation approach that handles both directional and direction-independent biases.
Data Source
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AI summary
The method involves measuring (401) a phase difference of signals for sensors, and determining (402) a value of attitude of an antenna, where the attitude is defined by a set of coordinates. A theoretical phase difference of the signals for each sensor is calculated (403) from arrival directions of the signals based on the attitude of the antenna. A skew for each sensor is determined (404) from the measured phase differences and from the theoretical phase differences of the sensor. An independent claim is also included for a signal receiver for receiving signals from signal sources.