Distributed Backscattering Disturbance Detection
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Solution Overview
Problem
Existing methods for detecting physical disturbances in communications links require coherent signal travel, which is not always possible, limiting their effectiveness.
Innovation Solution
A method using distributed backscattering in optical transmission links, where pairs of signal copies are transmitted and combined to generate a disturbance alert signal, leveraging backscattering centers like inhomogeneities in the transmission medium, eliminating the need for a reflector at the fiber end and allowing detection of dynamic disturbances without coherent signal requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coherent signal travel is required for disturbance detection, then detection reliability is improved, but system complexity and installation difficulty increase
Solution Approach 1:
The optical fiber itself serves as the sensing element through its intrinsic backscattering properties. The fiber's natural inhomogeneities act as distributed backscattering centers, eliminating the need for external sensors or complex coherent detection systems. The system uses the fiber's own characteristics to detect disturbances, making the fiber both the transmission medium and the sensing element.
Solution Approach 2:
Backscattered light acts as an intermediary carrier that conveys disturbance information back to the detection point. Instead of requiring direct coherent signal travel, the system uses backscattered light from inhomogeneities along the fiber to indirectly convey information about physical disturbances, enabling detection without maintaining coherent signals throughout the entire fiber length.
2Power
If a reflector is installed at the fiber end for signal return, then signal return strength is improved, but installation ease and adaptability deteriorate
Solution Approach 1:
The optical fiber utilizes its own intrinsic backscattering properties to return signals without requiring external reflectors. The distributed inhomogeneities along the fiber naturally provide the necessary signal return mechanism, eliminating the need for additional installation components and simplifying deployment in difficult-to-reach locations.
Solution Approach 2:
The patent extracts and utilizes the backscattering capability that already exists within the fiber medium itself, rather than adding external reflector components. By taking advantage of the fiber's inherent optical properties, the system removes the need for separate reflector installations while still achieving sufficient signal return for disturbance detection.
3Measurement precision
If coherent signal travel is required, then measurement precision is improved, but adaptability to different fiber installations deteriorates
Solution Approach 1:
The system changes the operational parameters from requiring coherent signal travel to utilizing incoherent backscattered light. This parameter change allows the system to adapt to various fiber installation conditions, lengths, and environments without requiring precise coherent signal maintenance, while still achieving sufficient disturbance detection precision through analysis of backscattered signal variations.
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 effective detection of physical disturbances, such as vibrations, without the need for a reflector, utilizing existing fiber installations and providing a sensitive surveillance system for monitoring optical fibers, even in difficult-to-reach locations.
Implementation Method 1
The distributed backscattering will preferably be Rayleigh scattering, caused by inhomogeneities in the transmission medium of the fibre
Implementation Method 2
signals are returned by a process of distributed backscattering along the optical transmission link
Implementation Method 3
combining one signal copy of a pair with the other signal copy of that pair, such that, from the combination of the two signal copies of a pair, a combination signal is generated
Data Source
AI summary
The present invention relates to a method for detecting or inferring a physical disturbances on a communications link, in particular by using distributed backscattering. The method includes the steps of: transmitting test signals onto a link; receiving test signals returned from a remote portion of the link; performing a function on the returned test signals; and in dependence on at least one characteristic of the combination signal, inferring the presence of a disturbance. The test signal are returned by a process Rayleigh backscattering along the fibre, so existing fibre installations can be used without requiring a mirror to be specifically introduced.