Enhanced Sensing Array for Undersea Acoustic Detection
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Solution Overview
Problem
Existing distributed acoustic sensing (DAS) systems in undersea optical cables suffer from reduced acoustic sensitivity due to the attenuation of acoustic waves by steel encasements, leading to less effective detection of acoustic disturbances.
Innovation Solution
The implementation of an enhanced sensing array with a DAS fiber coil surrounded by a low elastic modulus outer shell, which improves the phase response and sensitivity to acoustic signals by reducing the attenuation of acoustic waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel encasements are used to protect the optical cable, then the cable strength and protection are improved, but the acoustic sensitivity of the DAS system deteriorates due to attenuation of acoustic waves
Solution Approach 1:
The cable structure is segmented into distinct zones: armored sections for strength and sensing sections with low elastic modulus materials for acoustic sensitivity. The sensing section includes a DAS fiber coil surrounded by a low elastic modulus outer shell, separating the protection function from the sensing function to resolve the contradiction between cable strength and acoustic sensitivity
Solution Approach 2:
Different sections of the cable have different material properties tailored to their specific functions. The sensing sections use low elastic modulus materials (such as polymers or elastomers) to maximize acoustic wave transmission, while other sections may use steel armor for mechanical protection. This local differentiation allows the cable to simultaneously achieve both strength and acoustic sensitivity where needed
2Object-affected harmful factors
If the DAS fiber is encapsulated by steel material, then the cable protection is improved, but the acoustic wave strength reaching the sensor fiber is significantly attenuated
Solution Approach 1:
A low elastic modulus outer shell acts as an intermediary between the external acoustic environment and the DAS fiber coil. This intermediary material (such as a polymer or elastomer) transmits acoustic waves effectively to the sensor fiber while the DAS fiber remains protected within the sensing structure, resolving the contradiction between protection and acoustic wave transmission
3Measurement precision
If a low elastic modulus outer shell surrounds the DAS fiber coil, then the acoustic sensitivity is improved, but the device complexity increases
Solution Approach 1:
The sensing component merges multiple elements into an integrated unit: the DAS fiber coil is coiled and surrounded by the low elastic modulus outer shell, forming a compact sensing assembly. This merging approach improves acoustic sensitivity while containing the complexity within discrete, manageable modules rather than distributing it throughout the entire cable length
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 configuration significantly enhances the sensitivity of DAS systems, allowing for more effective detection of acoustic disturbances over longer distances, thereby improving the overall performance of undersea optical communication systems.
Implementation Method 1
the DAS system may be based on Rayleigh scattering or more particularly Rayleigh backscattering (otherwise referred to as a Rayleigh-scattering-based DAS system)
Implementation Method 2
The at least one sensing component may include a DAS fiber coil, forming a portion of the DAS fiber; and a low elastic modulus outer shell, surrounding the DAS fiber coil
Data Source
AI summary
A system for distributed acoustic sensing comprising. The system may include a distributed acoustic sensing (DAS) station to launch a DAS signal into a DAS fiber; and an enhanced sensing array, the enhanced sensing array comprising at least one sensing component. The at least one sensing component may include a DAS fiber coil, forming a portion of the DAS fiber, and a low elastic modulus outer shell, surrounding the DAS fiber coil.