Antenna Combiner Baseband Signal Processing
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Solution Overview
Problem
Electrically-steerable flat-panel antennas for satellite communications face challenges in achieving high bit rates due to insufficient signal-to-noise ratio (SNR) and gain-to-noise temperature (G/T) when receiving weak satellite signals, as existing RF combining techniques are not effective for enhancing the return satellite link transmission.
Innovation Solution
A system and method that combines signals from multiple satellite antennas to enhance receive link performance by coherently summing receive signals and dynamically selecting the best antenna for transmission based on signal quality, using Maximal Ratio Combining and antenna selection algorithms, while accounting for predicted motion and orientation changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple antenna elements are used for signal reception, then the signal-to-noise ratio can be improved through combining, but the device complexity increases due to the need for RF combining circuitry and signal coordination
Solution Approach 1:
The patent replaces complex RF-domain combining circuitry with a simpler baseband processing approach. Instead of using analog RF combiners and phase synchronizers, the system uses digital signal processing at baseband to achieve the same signal combining effect, thereby reducing hardware complexity while maintaining or improving the signal-to-noise ratio.
Solution Approach 2:
The patent introduces a baseband processing stage as an intermediary between the antenna elements and the final signal output. This baseband intermediary handles the signal combining and processing functions that would otherwise require complex RF circuitry, simplifying the overall system architecture while achieving the desired signal-to-noise ratio improvement.
2Reliability
If a single large aperture antenna is used to achieve high G/T ratio, then the reception performance is improved, but the device complexity and installation cost increase significantly
Solution Approach 1:
The patent divides a single large aperture antenna system into multiple smaller antenna elements. Each element contributes to the overall signal reception, and through coherent combining at baseband, the system achieves an equivalent G/T ratio to a single large antenna while using multiple smaller, simpler components that are easier to install and maintain.
Solution Approach 2:
The patent combines multiple small antenna elements to achieve the performance of a single large antenna. By merging the signals from multiple elements through baseband processing, the system achieves high G/T ratio without requiring a single large aperture structure, thereby reducing device complexity and installation costs.
3Device complexity
If antenna selection is used to simplify the system, then the device complexity is reduced, but the signal quality may deteriorate when switching between antennas due to fading conditions
Solution Approach 1:
The patent implements continuous signal combining from multiple antenna elements rather than intermittent switching between selected antennas. This continuous combining ensures that signal quality is maintained throughout transmission by constantly utilizing all available antenna elements, preventing the signal quality deterioration that can occur during antenna switching transitions.
Solution Approach 2:
The patent uses signal quality metrics as feedback to dynamically adjust the combining process. By continuously monitoring the quality of signals from each antenna element and using this feedback to optimize the combining weights and phases, the system maintains high signal quality while using all antenna elements, avoiding the quality losses associated with simple antenna selection.
Data Source
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AI summary
An antenna combiner with transmission arbitration and method for using the same are described. In one embodiment, the apparatus comprises a plurality of antennas to receive signals from a satellite, each antenna in the plurality of antennas having a transmit aperture and a receive aperture, and wherein the receive aperture is operable to receive one of the signals from the satellite; a plurality of signal analyzers coupled to the plurality of antennas, each signal analyzer operable to determine signal quality of a distinct one antenna of the plurality of antennas; an arbiter coupled to the plurality of signal analyzers and operable to select one antenna of the plurality of antennas to transmit to the satellite based on results of determining the signal quality; and a first selector coupled to the arbiter and the plurality of antennas to cause data to be sent to the one antenna selected for transmission to the satellite.