Satellite Digital Beam-Forming Error Correction
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Solution Overview
Problem
Current digital beam-forming techniques for space satellites are not sufficiently accurate for beam-pointing, leading to significant gain loss due to beam-pointing errors, especially in narrow spot beams.
Innovation Solution
A method and apparatus that digitize and process antenna element signals to separate and weight uplink and downlink signals, including beacon signals, to derive beam-pointing error signals, which are then used to adjust the pointing direction of communications beams, utilizing complex weight values for precise beam-forming and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If digital beam-forming techniques are used to provide narrow spot beams, then frequency reuse and gain are improved, but beam-pointing accuracy deteriorates leading to significant gain loss
Solution Approach 1:
The patent implements a feedback mechanism where ground beacons transmit reference signals that the satellite receives and processes. The satellite measures the actual beam-pointing error by comparing the received beacon signal characteristics against expected values, then feeds this error information back to adjust the beam-forming weights. This closed-loop feedback system continuously corrects pointing errors, maintaining high gain accuracy while preserving the frequency reuse benefits of narrow spot beams.
Solution Approach 2:
The patent replaces mechanical attitude adjustment mechanisms with electronic beam-pointing correction. Instead of physically moving the antenna to correct pointing errors, the system uses digital signal processing to adjust complex beam-forming weights in real-time. This substitution of mechanical correction with electronic correction enables faster, more precise adjustments without the inertia and mechanical wear limitations of physical repositioning systems.
2Measurement precision
If ground beacons are used for beam-pointing error correction, then pointing accuracy is improved, but system complexity increases
Solution Approach 1:
The patent makes the existing digital beam-forming processor multi-functional by enabling it to perform both its primary communication function and the secondary function of beacon signal processing for pointing error measurement. The same antenna elements and digital signal processing hardware that handle communication signals are also used to receive and process beacon signals. This eliminates the need for separate dedicated beacon reception hardware, reducing system complexity while maintaining high pointing accuracy.
Solution Approach 2:
The patent merges the beacon reception function with the existing digital beam-forming architecture. The beacon signal processing is integrated into the same digital signal processing chain that handles communication signals, combining multiple functions into a unified system. This integration shares hardware resources and processing capabilities, avoiding the complexity of separate independent systems while achieving accurate beam-pointing correction.
3Power
If beam-pointing error correction is implemented, then gain accuracy is improved, but processing overhead increases
Solution Approach 1:
The patent performs preliminary processing of beacon signals by extracting and identifying beacon components from the received signal spectrum before detailed error analysis. The system pre-processes the incoming signals to isolate beacon frequencies and characteristics, preparing the data in advance for error calculation. This preliminary action reduces the computational burden during real-time error correction, maintaining high gain accuracy while improving processing efficiency.
Solution Approach 2:
The patent extracts only the essential beacon signal components from the full received signal spectrum for processing. Instead of analyzing all communication signals, the system selectively identifies and extracts beacon signal characteristics (frequency, amplitude, phase) that are sufficient for pointing error measurement. This extraction approach reduces processing overhead by focusing computational resources only on the critical beacon data needed for correction, rather than processing the entire signal spectrum.
Data Source
AI summary
A digital method of determining and correcting beam-pointing for a communications spacecraft that has a digital beam-forming architecture for defining multiple spot transmit and receive beams, the antenna system of the spacecraft including a receive antenna (DRA, AFR) having antenna elements providing respective antenna element signals, and wherein at least one of the uplink signals to the spacecraft includes a beacon signal, and wherein the method comprises digitally weighting components of said beacon signal present in antenna element signals, combining such weighted beacon signal components such as to derive beam-pointing error signals, and employing the error signals to adjust beam-forming weight values of the receive antenna, in order to adjust the pointing direction of at least one signal beam. The digital weights for the beacon signal define difference radiation patterns for x, y axes of the antenna which vary rapidly in a range corresponding to the pointing errors most commonly occurring.