Distributed Acoustic Sensing Using Existing Fiber Optic Networks
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Solution Overview
Problem
Deploying dedicated optical fibers for distributed acoustic sensing is expensive and disruptive, especially in urban areas, and existing methods do not effectively utilize existing fiber-optic communication networks for this purpose.
Innovation Solution
A method that selects an existing optical fiber cable installation within a fiber-optic communications network, calibrates it geospatially, acoustically, and physically to reduce interference, and uses unused channels for distributed acoustic sensing, generating alert signals based on fluctuations in reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated optical fibre is deployed for distributed acoustic sensing, then the fibre optic conditions and parameters are known or well-controlled, but the installation becomes expensive and disruptive
Solution Approach 1:
The patent applies multi-functionality by enabling existing communication optical fibres to serve dual purposes: their original communication function and distributed acoustic sensing function. This eliminates the need for separate dedicated sensing fibres, reducing installation costs and disruption while utilizing already-deployed infrastructure
Solution Approach 2:
The patent changes the operational parameters of existing fibres by identifying and utilizing unused wavelength channels or unlit fibres within existing cable installations. This allows the fibres to be repurposed for acoustic sensing without requiring new physical installations, thereby maintaining reliability benefits while avoiding deployment costs
2Ease of manufacture
If existing optical fibre cable installations are used for distributed acoustic sensing, then installation cost and disruption are reduced, but fibre optic conditions and parameters are unknown or variable
Solution Approach 1:
The patent applies preliminary action by performing comprehensive calibration procedures before deploying the acoustic sensing function. This includes geospatial calibration to map fibre positions to geographical locations, acoustic calibration to characterize the fibre's acoustic response, and physical calibration to determine core properties and attenuation characteristics. These preliminary steps establish known parameters for existing fibres, enabling reliable sensing operation
Solution Approach 2:
The patent implements feedback mechanisms through the calibration process, where measured acoustic responses and physical properties are used to adjust and refine the sensing system's parameters. This feedback loop transforms the unknown characteristics of existing fibres into calibrated, reliable sensing channels with characterized performance
3Productivity
If existing optical fibre cable installations are used for distributed acoustic sensing, then unused channels are utilized, but acoustic interference from surrounding media must be filtered
Solution Approach 1:
The patent applies extraction by separating the desired acoustic sensing signal from unwanted interference through acoustic calibration. This process identifies and extracts the characteristic acoustic response of the fibre from the total measured signal, which includes both desired acoustic events and unwanted interference from surrounding media such as traffic or environmental noise
Solution Approach 2:
The patent converts the harmful effect of acoustic interference into a benefit by using the calibration process to characterize and model the interference patterns. Once characterized, these previously harmful signals become known parameters that can be filtered or compensated for, actually improving the system's ability to detect genuine acoustic events by distinguishing them from background noise
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
Enables cost-effective and non-disruptive detection of acoustic events by utilizing existing fiber-optic infrastructure, improving spatial accuracy and reducing false alarms through precise calibration and filtering, thus enhancing the effectiveness of acoustic event monitoring.
Implementation Method 1
receiving reflected light back scattered along the optical fibre, the reflected light including fluctuations over time
Data Source
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AI summary
Described herein is a method and system of distributed acoustic sensing, such as in an urban or metropolitan area involving a dedicated and established fibre optic communications network including a data centre. In general, the disclosed method and system includes the steps of (a) selecting an optical fibre cable installation having a path extending across a selected geographical area, the optical fibre cable installation including a bundle of optical fibres and forming part of a fibre-optic communications network, (b) determining characteristics associated with the optical fibre and/or the selected optical fibre installation, (c) transmitting outgoing light in the optical fibre, (d) receiving reflected light back scattered along the optical fibre, and (e) based on the reflected light and the determined characteristics, generating an alert signal representative of an acoustic event. The disclosed method and system may be useful in the detection of acoustic events near or within the selected geographical area.