Free-Space Optical Satellite Downlinks for High-Burst Data Transfer
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Solution Overview
Problem
Conventional satellite-to-earth data transmission systems are constrained by inefficient relay schemes and short-duration data transfers at low data rates, leading to a bottleneck in data collection capabilities, especially with increasing data generation from Earth-orbiting satellites.
Innovation Solution
The implementation of a free-space optical communications system that enables direct-to-Earth data transmission at extremely high burst rates (10 Gbps to 10 Tbps) using a network of compact, low-cost satellite and ground terminals, allowing for efficient data aggregation and transfer even under partly cloudy conditions, with forward error correction and feedback-based error correction mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional relay satellite schemes are used, then data transmission can be achieved, but data rate is limited and availability is restricted
Solution Approach 1:
The patent replaces conventional radio-frequency (RF) mechanical/electromagnetic transmission systems with optical transmission systems. Specifically, it uses laser-based free-space optical communication to transmit data from LEO satellites to ground stations, achieving data rates of 10 Gbps to 10 Tbps, which is orders of magnitude higher than traditional RF systems. This substitution resolves the contradiction by providing both high data rate and improved availability through direct optical links.
2Duration of action of moving object
If direct transmission is used, then connection time is short, but data transfer capability is restricted due to short connection time and restricted burst rates
Solution Approach 1:
The patent implements preliminary action by pre-buffering data on the satellite before the optical communication window opens. The satellite accumulates data in onboard storage during periods when ground stations are not visible, then rapidly transmits the buffered data during the brief optical communication window. This allows the system to achieve high data transfer capability despite limited connection time, as the actual transmission occurs at extremely high burst rates when the optical link is active.
Solution Approach 2:
The system employs periodic action by establishing optical communication links in periodic bursts as satellites pass over ground stations. Rather than attempting continuous transmission, the system captures data during each orbital pass window (typically a few minutes), then uses high-rate optical transmission to download accumulated data during these periodic opportunities. This approach maximizes data transfer capability within the constraints of short connection times.
3Quantity of substance
If RF spectrum is used for satellite transmissions, then data can be transmitted, but bandwidth and link availability are constrained by FCC regulations
Solution Approach 1:
The patent substitutes optical transmission for RF transmission to escape the constraints of FCC-regulated radio-frequency spectrum. By using laser-based free-space optical communication, the system accesses the unregulated optical spectrum, providing virtually unlimited bandwidth potential and avoiding RF spectrum allocation constraints. This substitution simultaneously improves both bandwidth capacity and link availability, as optical links are not subject to RF licensing restrictions and can operate in frequency bands that do not require FCC authorization.
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 solution enables fast and efficient data transfer of large volumes of data from low- to medium-Earth orbit satellites to ground stations, overcoming the limitations of traditional satellite communication systems by achieving high data rates and reliability despite atmospheric obstacles.
Implementation Method 1
transmitting, via the optical transmitter, the free-space optical signal
Implementation Method 2
receiving, from a spacecraft via a free-space optical channel, at a remote terminal... overcoming the limitations of traditional satellite communication systems by achieving high data rates and reliability despite atmospheric obstacles
Data Source
AI summary
Traditional satellite-to-earth data transmission systems are constrained by inefficient relay schemes and/or short-duration data transfers at low data rates. Communication systems described herein achieve extremely high burst rate (e.g., 10 Gbps or greater) direct-to-Earth (DTE) data transmission over a free-space optical link between a spacecraft and a remote terminal, which may be a ground terminal or another space terminal. The optical link is established, for example, when the remote terminal is at an elevation of 20° with respect to a horizon of the remote terminal. In some embodiments, a data transmission burst contains at least 1 Terabyte of information and has a duration of 6 minutes or less. The communication system can include forward error correction by detecting a degradation of a received free-space optical signal and re-transmitting at least a portion of the free-space optical signal.