Distributed Fiber-Optic Acoustic Sensing Coherent Integration
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Solution Overview
Problem
Current distributed fiber-optic acoustic sensing technologies face limitations in sensitivity and signal-to-noise ratio, leading to challenges in detecting weak sound signals and spatial orientation of signal sources, with existing solutions failing to effectively address interference fading and maintaining high spatial resolution.
Innovation Solution
A distributed fiber-optic acoustic sensing system that divides sensing units into subunits for spatially coherent combination of sound field signals, using sweep frequency pulse and pulse compression technology, phase-sensitive optical time-domain reflectometers, and coherent detection to enhance signal-to-noise ratio and sensitivity, allowing for azimuth estimation and space orientation without altering the sensing optical fiber structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If distributed fiber-optic acoustic sensing is based on Rayleigh scattering effect, then detection distance and spatial coverage are improved, but sensitivity and signal-to-noise ratio deteriorate due to weak scattered signal amplitudes
Solution Approach 1:
The patent combines multiple sensing units along the optical fiber to form a sensor array, merging their individual weak signals through coherent integration. This allows the system to maintain long detection distance while improving sensitivity by aggregating signals from N sensing units, achieving a sensitivity improvement proportional to the square root of N through constructive interference of the combined signals.
2Area of stationary object
If distributed fiber-optic acoustic sensing is based on Rayleigh scattering effect, then spatial coverage and distributed detection capability are improved, but signal-to-noise ratio deteriorates due to weak scattered signals
Solution Approach 1:
The patent merges signals from multiple spatially distributed sensing units through coherent integration, maintaining the broad spatial coverage advantage while improving signal-to-noise ratio by constructively combining weak scattered signals from N different locations along the optical fiber.
Solution Approach 2:
The patent employs dynamic signal processing through coherent integration that adaptively combines signals from multiple sensing units based on their phase relationships, enabling the system to dynamically enhance signal-to-noise ratio while preserving the distributed spatial coverage capability across the entire sensing length.
3Measurement precision
If sensing units are divided into subunits for spatially coherent combination, then sensitivity and signal-to-noise ratio are improved, but device complexity increases due to additional signal processing requirements
Solution Approach 1:
The patent segments the optical fiber into multiple sensing units and further divides them into subunits for independent signal processing. This segmentation allows coherent integration to be performed on manageable groups of units while maintaining overall system sensitivity improvement, balancing the complexity of signal processing with the benefits of enhanced measurement precision.
4Ease of manufacture
If distributed fiber-optic acoustic sensor uses conventional sensitivity index, then system simplicity and ease of manufacture are maintained, but measurement capability for weak sound signals deteriorates
Solution Approach 1:
The patent combines multiple conventional fiber-optic sensing units into a coherent array system, transforming individually simple sensors into a collective system with enhanced detection capability for weak sound signals while maintaining compatibility with standard fiber-optic manufacturing processes.
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
The system significantly improves signal-to-noise ratio and sensitivity by two to three orders of magnitude, enabling effective detection of weak signals and spatial orientation of sources over long distances, while maintaining high spatial resolution and addressing interference fading.
Implementation Method 1
Most of the current distributed fiber-optic acoustic sensing technologies are based on the Rayleigh scattering effect in the optical fiber
Implementation Method 2
a coherent detection unit connected to a second port of the second fiber-optic coupler and configured to perform coherent detection on the backscattered light signals
Data Source
AI summary
A distributed fiber-optic acoustic sensing system and a signal processing method. The distributed fiber-optic acoustic sensing system is based on a high spatial resolution distributed fiber-optic acoustic sensor. The interval between adjacent sensing units is centimeter or millimeter level. Through specific digital signal processing, signal enhancement can be realized, noise in the system and environment are suppressed, at the same time, problems such as interference fading is solved, and the sensor signal-to-noise ratio of subunits can be increased by two to three orders of magnitude. Each subunit can serve as an independent high-sensitivity sensor for sensing. The multiple subunits can form one or more new sensor arrays. The azimuth estimation and spatial orientation of signal sources can be realized by the array signal processing method.