Bidirectional Multi-Wavelength Fiber Network for Aircraft LRUs
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Solution Overview
Problem
Existing fiber optic networks in airplanes require a large number of glass optical fiber cables, which are costly and prone to issues with dust, contamination, and misalignment due to vibration, and are not compatible with multimode fibers used onboard commercial transport aircraft.
Innovation Solution
A bidirectional, multi-wavelength fiber optical network utilizing a single gigabit plastic or glass optical fiber that reduces the number of fiber cables by using a single-fiber multi-mode link with high-directional couplers and low-reflection connectors, enabling efficient communication between line replaceable units with minimal optical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of glass optical fiber cables are used to connect LRUs, then communication coverage is improved, but weight, cost, and complexity increase significantly
Solution Approach 1:
The patent combines multiple communication channels into a single optical fiber by implementing bidirectional communication where one fiber carries both transmit and receive signals. This merging approach reduces the number of separate fiber cables needed to connect LRUs, directly addressing the weight and complexity issues while maintaining comprehensive communication coverage throughout the aircraft.
Solution Approach 2:
The optical fiber is designed to serve multiple functions simultaneously - carrying both transmit and receive signals in opposite directions through the same physical medium. This multi-functionality allows a single fiber cable to replace what would traditionally require separate dedicated cables for each communication direction, reducing overall cable weight and installation complexity while maintaining full communication capability between all LRUs.
2Speed
If glass optical fiber cables are used, then bandwidth and speed are improved, but sensitivity to dust, contamination, and misalignment increases
Solution Approach 1:
The patent employs plastic optical fiber (POF) connectors that are more tolerant of contamination and misalignment compared to traditional glass fiber connectors. While POF has slightly different transmission characteristics, it provides sufficient bandwidth for aircraft communication needs while being significantly more robust against dust and contamination, reducing maintenance requirements and improving reliability in harsh avionic environments.
3Reliability
If multiple fiber cables are installed to connect all LRUs, then communication reliability is improved, but installation cost and complexity increase
Solution Approach 1:
The patent implements a star-topology network where all LRUs connect to a central hub through individual bidirectional fiber links, eliminating the need for mesh connectivity between all pairs of LRUs. This merging approach reduces the total fiber count from O(N²) to O(N), significantly lowering installation cost and complexity while maintaining communication reliability through the centralized architecture that provides alternative paths for fault tolerance.
4Adaptability or versatility
If single-mode fiber is used for WDM systems, then wavelength multiplexing capability is improved, but sensitivity to vibration and shock increases
Solution Approach 1:
The patent adopts plastic optical fiber (POF) with multimode capability instead of single-mode fiber for WDM implementations. While POF has larger core dimensions that traditionally limit WDM performance, advances in POF technology and optimized connector designs enable sufficient wavelength division multiplexing capability for aircraft applications. The multimode POF provides robustness against vibration and shock while maintaining adequate wavelength multiplexing functionality for reducing fiber counts in aircraft networks.
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 significantly reduces the number of fiber cables needed, lowering weight, size, and installation costs while maintaining high data transmission rates and electromagnetic immunity, and is compatible with both plastic and glass optical fibers.
Implementation Method 1
each transceiver includes an optical filter, a laser, and a photodetector... the optical filter of the first and second transceivers passes light having the first wavelength and reflects light having the second wavelength
Implementation Method 2
a laser disposed to transmit light through the optical filter... the laser of the first transceiver emits light having a first wavelength
Implementation Method 3
a photodetector disposed to receive light reflected by the optical filter... the photodetector of the first and second transceivers receives light having the second wavelength
Implementation Method 4
An optical fiber is a cylindrical dielectric waveguide that transmits light along its axis... Light is kept in the core by the phenomenon of total internal reflection
Data Source
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AI summary
A bidirectional, multi-wavelength fiber optical network that enables communication between electrical components (such as line replaceable units) at high data transmission rates. The proposed fiber optical network in accordance with some embodiments comprises a single plastic or glass optical fiber capable of transmitting data at rates faster than 1 Gbits/sec. In accordance with some embodiments, the number of fiber cables between line replaceable units onboard an airplane can be reduced by a factor of eight or more by substituting one gigabit plastic or gigabit glass optical fiber for four or more plastic or glass optical fibers.