Antenna Tracking Control with Phase Correction for Low-SNR Signals
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Solution Overview
Problem
Existing antenna tracking systems face challenges in accurately tracking communication satellites with low signal-to-noise ratios and narrow antenna beam widths, leading to inaccurate phase adjustments and potential loss of tracking capability.
Innovation Solution
The development of an antenna control device that calculates and applies phase correction values and sensitivity coefficients to accurately orient the antenna beam, even in low signal-to-noise conditions, by using error measurement data to minimize phase and sensitivity shifts during tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase adjustment methods (sun tracking or two-point calibration) are used, then the system can be operated, but tracking accuracy deteriorates in low signal-to-noise ratio conditions
Solution Approach 1:
The system performs preliminary calibration by storing reference values for sum signals and difference signals at multiple known orientation angles before tracking begins. These reference values are established when strong calibration signals are available, then used during actual tracking to accurately determine antenna orientation even when reception signals are weak
Solution Approach 2:
The system continuously compares current sum and difference signals against the stored reference values, calculates orientation angles from these comparisons, and uses this feedback to adjust and maintain accurate tracking. The reference values provide a stable baseline for continuous orientation measurement
2Measurement precision
If the antenna beam width is made narrow to improve spatial selectivity, then directional accuracy is improved, but the ability to track satellites with low signal-to-noise ratio deteriorates
Solution Approach 1:
Reference signals are stored during a calibration phase when the antenna can be positioned at multiple known angles and strong calibration signals are available. This preliminary data collection enables accurate orientation determination during subsequent tracking of weaker signals
Solution Approach 2:
The system replaces reliance on mechanical signal strength with signal processing-based orientation determination. By comparing phase and amplitude relationships between sum and difference signals against reference values, the system determines orientation without depending on the absolute strength of received signals
3Adaptability or versatility
If complex signal processing circuits are used to derive sum and difference signals, then tracking functionality is achieved, but phase mismatch between sum and difference signals increases
Solution Approach 1:
The system introduces reference values as an intermediary element between the complex signal processing circuits and the orientation determination process. These reference values, captured during calibration when phase relationships are known, serve as a mediator that enables accurate orientation measurement despite the phase-introducing complexity of the processing circuits
Solution Approach 2:
The system changes the approach from attempting to maintain perfect phase matching in the circuits to instead capturing the actual phase relationships during calibration and using those captured parameters for orientation determination. This parameter-based approach accommodates circuit imperfections
Data Source
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AI summary
The present invention obtains a correction value that corrects measurement angle error signals more accurately than conventional methods even in a case where a radio wave signal-to-noise ratio is low, and thus tracks a communication counterpart more accurately than the conventional methods. The present invention includes a program controller 28 that generates a command value of an orientation direction of an antenna 1 and outputs the generated command value to an antenna drive controller 27, the command value being changed in accordance with a predetermined change scenario 54; a correction value calculator 32 that calculates a phase correction value γ, based on at least three pieces of error measurement data 55 including (i) an arrival direction error obtained from a sum signal and a difference signal of reception signals, the arrival direction error representing a difference between the orientation direction and an arrival direction being a direction from which the radio waves come and arrive and (ii) an orientation direction actual measurement value being an actual measurement value of the orientation direction when the arrival direction error is obtained, the phase correction value γ being an angle by which the arrival direction error is rotated; and a tracking controller 33 that outputs, to the antenna drive controller 27, as the command value, a value obtained by adding the arrival direction error corrected based on the phase correction value γ to the orientation direction actual measurement value.