Ground Based Beamforming for Satellite Optical Feeder Links
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Solution Overview
Problem
Current satellite communication systems face challenges in efficiently routing large amounts of bandwidth between ground-based gateways and satellites, particularly with the increasing demand for high-throughput satellite services, as RF feeder links require numerous ground stations and are costly, whereas optical feeder links can significantly reduce the number of ground stations needed but require complex onboard processing.
Innovation Solution
Implementing an optical communication system that uses analog-over-free-space optics to transmit and receive signals between ground-based gateways and satellites, eliminating the need for high-speed Analog-to-Digital Converters and Digital to Analog Converters on satellites, and allowing for ground-based beamforming even at high frequencies like Ka band, by modulating optical wavelengths at desired RF frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed Analog-to-Digital Converters and Digital to Analog Converters are placed on satellites, then signal processing capability is improved, but mass and power consumption increase
Solution Approach 1:
The patent removes the heavy and power-intensive analog-to-digital and digital-to-analog converters from the satellite and places them on the ground. This extraction significantly reduces satellite mass and power consumption while maintaining full signal processing capability through ground-based equipment
2Productivity
If high-speed Analog-to-Digital Converters and Digital to Analog Converters are placed on satellites, then signal processing capability is improved, but power consumption increases
Solution Approach 1:
The patent extracts the power-intensive converter functions from the satellite to ground-based equipment, dramatically reducing satellite power consumption. The complex signal processing is performed on the ground where power is more readily available, allowing the satellite to operate with minimal power expenditure for feeder link operations
3Object-affected harmful factors
If RF frequency spectrum constraints are observed, then interference is reduced, but beamforming flexibility is limited
Solution Approach 1:
The patent substitutes optical frequencies for RF frequencies in the feeder link, replacing the constrained RF electromagnetic spectrum with the vastly broader optical spectrum. This substitution eliminates RF spectrum constraints and interference issues while enabling highly flexible beamforming through ground-based phase and amplitude control of optical signals
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies satellite payload design, reduces mass and power consumption, and enables flexible beamforming without the limitations of RF frequency spectrum constraints, while achieving high throughput and cost savings by reducing the number of ground stations required.
Implementation Method 1
analog-over-free-space optics to transmit and receive signals between ground-based gateways and satellites, eliminating the need for high-speed Analog-to-Digital Converters and Digital to Analog Converters on satellites, and allowing for ground-based beamforming even at high frequencies like Ka band, by modulating optical wavelengths at desired RF frequencies
Data Source
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Figure 2B
AI summary
Described herein are ground based subsystems (200), and related methods, for use in transmitting an optical feeder uplink beam (102u) to a satellite (100) that includes a multiple element antenna feed array and that is configured to accept the optical feeder uplink beam (102u) and in dependence thereon use the multiple element antenna feed array to produce and transmit a plurality of radio frequency (RF) service downlink beams (106d, 110d, 114d) to service terminals (STs). Certain embodiments are related to a ground based beamformer (GBBF) (230) for inclusion in a ground based subsystem (200), and methods for use therewith. Beneficially, embodiments described herein allow for flexible antenna beam forming for large signal bandwidth without the limitation associated with the available gateway uplink and downlink spectrum at RF frequencies. Also described herein are space based subsystems for use with such ground based subsystems (200).