Satellite Beamforming Calibration via Multi-Frequency Tone Injection
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Solution Overview
Problem
Existing satellite systems face challenges in calibrating phase and amplitude offsets across multiple beams within their operational frequency range due to equipment and environmental factors, leading to inadequate calibration across all frequencies.
Innovation Solution
A calibration apparatus and method that determines and corrects phase and amplitude shifts in satellite transmission paths by injecting calibration tones and measuring offsets at various frequencies, allowing for accurate beam formation and frequency translation adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If prior art calibration systems are used, then calibration can be performed at a single frequency, but calibration coverage across all operational frequencies is insufficient
Solution Approach 1:
The calibration apparatus is designed to perform calibration across multiple frequency ranges by incorporating a signal generator capable of generating test signals at different frequencies and a controller that coordinates calibration measurements across the full operational bandwidth of the satellite system, making the system universally applicable to all frequency operations
Solution Approach 2:
The system changes the frequency parameter of test signals during calibration by using a signal generator to produce signals at multiple frequencies within the operational range, and the controller adjusts measurement parameters accordingly to capture phase and amplitude characteristics across the entire frequency spectrum
2Ease of manufacture
If calibration is performed only before launch, then initial system setup is simple, but phase and amplitude differentials develop due to age and temperature changes
Solution Approach 1:
The satellite system performs self-calibration operations autonomously in orbit by using an on-board signal generator to generate test signals and a controller to coordinate measurements and adjust beam weights, maintaining communication quality without requiring ground-based intervention or complex preliminary ground calibration procedures
Solution Approach 2:
The satellite system calibrates itself autonomously by generating its own test signals through an on-board signal generator, measuring phase and amplitude characteristics using existing receiver chains, and automatically adjusting beam weights through controller processing without external assistance, making the system self-maintaining in orbit
3Measurement precision
If beam weights are adjusted to compensate for phase and amplitude offsets, then beam formation accuracy improves, but system complexity increases due to calibration equipment and procedures
Solution Approach 1:
The patent uses existing receiver chains and signal processing equipment as intermediaries to perform calibration measurements, rather than introducing separate dedicated measurement equipment. The beam weights themselves serve as the intermediary mechanism to both create the test signals and measure the phase/amplitude characteristics, simplifying the overall system architecture
Solution Approach 2:
The existing receiver chains and signal processing equipment are made multi-functional by using them both for normal communication signal reception and for calibration measurements. The same hardware components that process user communications are also utilized to generate test signals and measure phase/amplitude characteristics, eliminating the need for separate calibration hardware
Data Source
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AI summary
There is provided an apparatus for calibrating a multi-beam satellite system comprising a beam forming network providing a plurality of signal paths, the apparatus comprising a calibration processor for determining the phase and amplitude shift of a test path of the plurality of signal paths by correlating a calibration tone extracted from the test path with a reference calibration signal, the calibration processor being configured to determine the phase and amplitude shifts of the test path for at least two calibration tones of at least two different frequencies. The apparatus also comprises means for applying a correction based on the determined phase and amplitude shift to the test path in the beam forming network. The two calibration tones of at least two different frequencies may be calibration tones injected at two different frequencies but also calibration tones translated into two different frequencies by the beam forming network. The invention allows a phase and amplitude shift for any path through the beam forming network to be calculated for any frequency in an operational frequency range of the multi-beam satellite system and corrections to be applied to form or interpret the required downlink or uplink beams of the multi-beam satellite system.