Interleaved Optical Signal Amplification for Free Space Communications
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Solution Overview
Problem
Free-space optical communication systems face challenges in accurately determining the angular direction of moving platforms due to reduced signal power and difficulty in initial acquisition and tracking, especially when using separate data and beacon signals, which increases system size, weight, and power requirements.
Innovation Solution
Generating a data signal and a beacon signal with different optical wavelengths, where the beacon signal is an inverted version of the data signal and modulated at a lower rate, allowing both signals to be optically combined and amplified using a single amplifier, thereby maintaining full power amplification for the data signal without increasing system size, weight, or power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separate beacon signal is generated and transmitted for acquisition and tracking, then the beamwidth is increased for better acquisition and tracking capability, but the system size, weight, and power requirements are doubled
Solution Approach 1:
The patent combines the data signal and beacon signal into a single optical transmission by time-interleaving them. The data signal and inverted beacon signal are multiplexed in the time domain, allowing both functions to be performed with a single laser source and single amplifier, thereby avoiding the doubling of system size, weight, and power requirements while maintaining separate beamwidth characteristics for each signal type
Solution Approach 2:
The patent employs periodic time-interleaved transmission where the data signal and beacon signal are transmitted in alternating time slots. The beacon signal is inverted and modulated at a lower rate, creating a periodic pattern that allows the single amplifier to serve both signals effectively while maintaining distinct functional characteristics for acquisition and tracking versus data transmission
2Device complexity
If the data signal is used for both data reception and angular position detection, then the system complexity is reduced, but the signal power available for data reception is reduced
Solution Approach 1:
The patent segments the transmission function by creating distinct time slots for data signal transmission and beacon signal transmission. The data signal carries full-power data information during its allocated time slots, while the inverted beacon signal carries acquisition and tracking information during separate time slots. This temporal segmentation allows full signal power to be dedicated to each function without splitting the power between detectors
Solution Approach 2:
The patent introduces an inverted version of the data signal as an intermediary beacon signal. This inverted signal serves as the mediator for angular position detection and acquisition functions, allowing the original data signal to maintain full power for data reception without being divided for dual purposes
3Power
If the beamwidth of the data signal is minimized to maximize signal strength and operating range, then the data signal power is maximized, but the initial acquisition of remote terminal becomes difficult
Solution Approach 1:
The patent uses periodic time-interleaved transmission where narrow beamwidth data signals are transmitted during data slots and wider beamwidth beacon signals are transmitted during beacon slots. This periodic alternation allows the system to achieve both narrow beam benefits for data transmission and wide beam benefits for initial acquisition and tracking
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 enables effective acquisition and tracking without reducing data signal power, simplifies beacon detection, and maintains system efficiency by using a single amplifier for both signals, thus enhancing the operating range and reliability of free-space optical communications.
Implementation Method 1
the combined signal is amplified via a fiber amplifier
Implementation Method 2
amplified via an erbium-doped fiber amplifier
Data Source
AI summary
A technique for generating a data signal and a beacon signal for free space optical communications involves generating a data signal having a first optical wavelength and a beacon signal having a second optical wavelength. The data signal is encoded with data via modulation at a first modulation rate. The beacon signal is an inverted version of the data signal and can be further modulated at a second modulation rate that is less than the first modulation rate. The data and beacon signals are optically combined to produce a combined signal in which power attributable to the beacon signal is interleaved with and substantially non-overlapping temporally with power attributable to the data signal. The combined signal is amplified via a fiber amplifier, and the combined signal is supplied to transmitter optics for transmitting the data signal and the beacon signal into free space.