Optical Feeder Uplink for Satellite RF Downlink Systems
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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 space-based satellites, particularly due to the need for numerous RF frequency feeder links, which are costly and require significant infrastructure.
Innovation Solution
Implementing optical feeder links between ground-based gateways and space-based satellites, utilizing analog-over-free-space optical signals to eliminate the need for high-speed Analog-to-Digital Converters and Digital to Analog Converters on satellites, and simplifying payload design by eliminating frequency conversion in the forward link.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF frequency feeder links are used to route bandwidth between ground-based gateways and space-based satellites, then reliable communication is achieved, but the number of ground stations increases and costs increase significantly
Solution Approach 1:
The patent replaces the traditional RF (radio frequency) mechanical/electromagnetic wave transmission system with an optical transmission system using lasers and photodetectors. This substitution enables higher bandwidth transmission through optical feeder links, reducing the number of ground stations required while maintaining communication reliability. The optical system transmits data as light signals between ground-based optical transmitters and satellite-based optical receivers, eliminating the need for numerous RF feeder links.
2Quantity of substance
If optical feeder links are implemented to reduce the number of ground stations, then cost and infrastructure are reduced, but new technical challenges arise in signal transmission and reception
Solution Approach 1:
The patent introduces optical intermediaries including optical transmitters on the ground, optical amplifiers, wavelength division multiplexing equipment, and photodetectors on the satellite. These intermediary components facilitate the conversion and transmission of signals in the optical domain, managing the complexity of optical feeder links while enabling reduced ground station infrastructure. The intermediaries handle signal conditioning, amplification, and conversion between optical and electrical domains.
Solution Approach 2:
The patent segments the optical signal transmission into multiple wavelength channels using wavelength division multiplexing (WDM). By dividing the total bandwidth into separate wavelength channels, each carrying independent data streams, the system manages transmission complexity through modular channel handling. This segmentation allows multiple signals to be transmitted simultaneously over the same optical path, reducing the need for multiple ground stations while organizing signal management into manageable wavelength segments.
3Productivity
If high-speed Analog-to-Digital Converters and Digital to Analog Converters are used on satellites for RF signals, then signal processing capability is improved, but satellite mass, power consumption, and complexity increase
Solution Approach 1:
The patent replaces the electronic signal processing system requiring high-speed ADCs and DACs with an optical signal processing system. By transmitting data directly as optical signals and using photodetectors for reception, the satellite eliminates the need for high-speed electronic converters. This substitution maintains signal processing capability while dramatically reducing satellite mass, power consumption, and complexity associated with high-speed electronic conversion equipment.
4Adaptability or versatility
If frequency conversion is performed in the forward link to accommodate different service beams, then service versatility is improved, but payload complexity and power consumption increase
Solution Approach 1:
The patent segments the service beam signals into different wavelength channels using wavelength division multiplexing, eliminating the need for frequency conversion in the forward link. Each service beam is assigned a specific wavelength, allowing multiple beams to coexist without interference. This segmentation approach maintains service versatility while removing complex frequency conversion equipment from the satellite payload, reducing both payload complexity and power consumption.
Solution Approach 2:
The patent transitions from frequency-domain signal separation (requiring frequency conversion) to wavelength-domain signal separation using optical multiplexing. By exploiting the wavelength dimension of optical signals, the system accommodates multiple service beams simultaneously without requiring frequency conversion hardware. This dimensional shift from RF frequency manipulation to optical wavelength multiplexing simplifies the payload while maintaining service versatility.
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 reduces the number of ground stations required, lowers costs, and increases satellite capacity to Terabit/sec levels while minimizing mass, power, and complexity, enabling more efficient data transmission and reception.
Implementation Method 1
an optical transmitter converts a plurality of electrical signals to a plurality of optical signals
Implementation Method 2
an optical receiver converts the plurality of optical signals to a plurality of electrical signals
Data Source
AI summary
Described herein are ground based subsystems, and related methods, for use in transmitting an optical feeder uplink beam to a satellite that is configured to receive the optical feeder uplink beam and in dependence thereon produce and transmit a plurality of RF service downlink beams within a specified RF frequency range to service terminals. Also described herein are space based subsystems of a satellite, and related methods, for use in transmitting a plurality of RF service downlink beams within a specified RF frequency range to service terminals. Beneficially certain embodiments eliminate the need for any frequency down-converters or any other type of frequency conversion equipment in a space segment forward link equipment. Also described herein is space segment return link equipment, and related methods, for use in transmitting an optical feeder downlink beam to a ground based subsystem, as well as ground based return link equipment thereof.