Satellite Antenna Alignment Using Arbitrary Orientation Attitude
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Solution Overview
Problem
Existing satellite communication systems on mobile platforms face challenges in accurately aligning antennas due to errors in roll, pitch, and yaw, which result in pointing errors when using position and attitude measuring devices (PAMD) outputs, as corrections are orientation-specific and do not translate accurately across different orientations.
Innovation Solution
A method and apparatus that involve placing the mobile platform in various orientations, measuring vectors from the platform to the satellite, and using these measurements to determine rotation matrices that account for roll, pitch, and yaw offsets between the PAMD and antenna reference frames, allowing for accurate antenna alignment across different orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If antenna alignment corrections are determined for a particular orientation using peaking, then the antenna pointing accuracy is improved for that specific orientation, but the corrections become inaccurate when applied to other orientations of the mobile platform
Solution Approach 1:
The system performs preliminary alignment measurements at multiple predetermined orientations (e.g., 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°) before actual operation. These preliminary measurements establish a comprehensive set of correction values that can be interpolated for any orientation during flight, eliminating the need for real-time re-alignment and ensuring accuracy across all orientations.
Solution Approach 2:
The alignment system is designed to work across all orientations of the aircraft by collecting data at multiple predetermined orientations. The correction values obtained from these diverse orientations create a universal alignment solution that can be applied regardless of the aircraft's attitude, making the system adaptable to any flight condition.
2Measurement precision
If the aircraft is placed in multiple orientations for alignment measurements, then the alignment accuracy across all orientations is improved, but the alignment procedure time is increased
Solution Approach 1:
The alignment procedure is performed as a preliminary action during ground operations (taxiing, pre-flight preparation) when the aircraft can be easily positioned at predetermined orientations. By completing this comprehensive alignment process before flight, the system ensures high accuracy without adding time to the actual flight operations.
Solution Approach 2:
The alignment measurements are taken at periodic intervals at predetermined orientations (e.g., every 45 degrees). This structured periodic approach allows for systematic data collection that can be completed efficiently during ground operations, balancing the need for comprehensive measurements with time constraints.
Data Source
AI summary
Systems and methods for aligning a satellite antenna mounted on a mobile platform to the platform. At each of several arbitrary orientations, a first directional vector is determined from the antenna to a satellite. For each orientation, an alias transformation is performed to transform the first vector having coordinates defined with respect to a first reference frame to a second vector having coordinates defined with respect to a second reference frame. A third vector is determined based on the orientation of the antenna after peaking the antenna. A rotation matrix is derived from the collection of second and third vectors. An estimate of the rotational offset of the satellite antenna with respect to the platform is determined based on the rotation matrix. The rotational offset is applied to the attitude of the platform to accurately point the antenna to the satellite.