Distributed Acoustic Sensing via Submarine Cable Repeaters
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Solution Overview
Problem
Monitoring vast marine environments for ISR (intelligence, surveillance, and reconnaissance) is logistically difficult and expensive due to the limitations of existing methods, which often require permanent power and communication sources for fibre-optic distributed acoustic sensing systems.
Innovation Solution
A system and method utilizing fibre-optic submarine communications cables with distributed acoustic sensing units, powered by repeaters, that transmit and multiplex acoustic data through existing fibre-optic submarine communications cables, enabling permanent monitoring without the need for permanent power or communication sources, and incorporating magneto-restrictive coatings for magnetic sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If fibre-optic distributed acoustic sensing is deployed in vast marine environments, then monitoring coverage area is improved, but logistical difficulty and cost increase
Solution Approach 1:
The system utilizes existing fibre-optic submarine communications cables for multiple purposes: both their original communication function and as sensing cables for distributed acoustic sensing. This eliminates the need for separate dedicated sensing cable deployments across vast marine areas, significantly reducing logistical complexity while maintaining large monitoring coverage
Solution Approach 2:
The repeaters along the fibre-optic cable, which originally served only for signal amplification in communication, are repurposed to provide power and communication services to the DAS units. This self-service approach eliminates the need for separate power cables and communication infrastructure, reducing operational logistics while enabling permanent monitoring across extensive areas
2Reliability
If permanent power and communication sources are provided for DAS units, then sensing reliability is improved, but device complexity and cost increase
Solution Approach 1:
The existing fibre-optic communication infrastructure is made multi-functional by using the same cables and repeaters for both communication and power/control of DAS units. This integration reduces system complexity while ensuring permanent, reliable power and communication connections for continuous sensing operation
Solution Approach 2:
The system merges the communication infrastructure with the power distribution and control systems for DAS units. By combining these functions into a single integrated fibre-optic network with repeaters, the system achieves permanent reliable connections without the complexity of separate power and communication systems
3Measurement precision
If hydrophone detectors are used for acoustic sensing, then acoustic event detection capability is improved, but power and communication requirements increase system complexity
Solution Approach 1:
The system replaces traditional electrical hydrophone detectors with fibre-optic-based acoustic sensing. The fibre-optic cable itself acts as the sensing element, using optical properties (such as Rayleigh backscattering) to detect acoustic disturbances, thereby eliminating the need for complex electrical hydrophone assemblies with their associated power and communication requirements
Solution Approach 2:
The fibre-optic cable serves dual purposes: as the transmission medium for communication and as the sensing element for acoustic detection. This multi-functionality eliminates the need for separate hydrophone detectors, reducing system complexity while maintaining acoustic event detection capability through optical property changes in the fibre
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 provides effective and permanent monitoring of vast marine environments with improved accuracy and reduced logistical challenges, enabling covert and efficient surveillance of acoustic and magnetic disturbances.
Implementation Method 1
a receiver configured to receive reflected light of the outgoing light that has been back scattered along the at least one fibre-optic sensing cable
Implementation Method 2
the reflected light including at least one optical property influenced by an acoustic disturbance in the marine environment
Implementation Method 3
an optical multiplexer for multiplexing optical signals onto the fibre-optic submarine communications cable via the repeater, the optical signals carrying information on the at least influenced optical property
Implementation Method 4
the at least one of the fibre-optic sensing cables is provided with a magneto-restrictive coating for distributed magnetic sensing in the marine environment surrounding the repeater
Data Source
AI summary
The present invention relates to a system for distributed acoustic sensing in a marine environment surrounding a repeater along a fibre-optic submarine communications cable. The system includes at least one distributed acoustic sensing (DAS) unit. Each DAS unit further includes a light source that is configured to transmit outgoing light in at least one fibre-optic sensing cable that is located in the marine environment and a receiver configured to receive reflected light that includes at least one optical property influenced by an acoustic disturbance in the marine environment. Each DAS unit further includes an optical multiplexer for multiplexing optical signals onto the fibre-optic submarine communications cable via the repeater where the optical signals carry information on the at least influenced optical property. A method for distributed acoustic sensing in the marine environment is also disclosed.