Fiber Line Monitoring with Loopbacks for Perturbation Localization
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Solution Overview
Problem
Existing systems lack the capability to precisely spatially resolve perturbations external to an optical fiber transmission system, such as earthquakes, using line monitoring equipment.
Innovation Solution
A line monitoring system employing a laser source, optical transmission system with loopbacks, and a receiver to measure phase differences between return signals from loopbacks, determining the location of perturbations based on these differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If line monitoring equipment is used to detect perturbations in optical fibers, then perturbation detection capability is improved, but spatial resolution precision deteriorates
Solution Approach 1:
The optical transmission system is divided into multiple segments using loopbacks at different locations along the fiber. Each loopback reflects a portion of the probe signal back to the receiver, creating discrete measurement points that enable spatial resolution of perturbations along the fiber length.
Solution Approach 2:
The system transitions from detecting only the presence of perturbations to measuring multiple dimensions of perturbation characteristics including spatial location, phase differences, and polarization changes. This multi-dimensional measurement approach enables precise spatial resolution by comparing phase differences across multiple loopback points.
2Measurement precision
If multiple loopbacks are used to improve spatial resolution, then device complexity increases
Solution Approach 1:
The loopback structures serve multiple functions: they reflect probe signals back to the receiver, provide spatial reference points for localization, and enable phase difference measurements. This multi-functionality reduces the need for separate dedicated components for each measurement objective.
Solution Approach 2:
The system uses the existing optical transmission infrastructure and its inherent loopback points as measurement references, rather than requiring entirely separate sensing equipment. The transmission system itself provides the measurement framework through its existing structural features.
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 the detection and precise localization of perturbations, such as subsea earthquakes, by analyzing phase changes in polarization across multiple loopbacks in an optical transmission system.
Implementation Method 1
communications over fiber optic cables takes place using pulses of light
Implementation Method 2
The line monitoring equipment may be used to send probe signals and detect return signals
Implementation Method 3
a perturbances detection system, coupled to the receiver, to measure a phase difference between a polarization of a pair of return signals
Data Source
Figure 1
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Figure 3A~3C
AI summary
A line monitoring system may include a laser source to launch a plurality of pulsed probe signals; an optical transmission system, comprising a plurality of loopbacks, to receive the plurality of pulsed probe signals, and direct the plurality of pulsed probe signals through the plurality of loopbacks. The system may include a receiver to receive a plurality of return signals, derived from the plurality of pulsed probe signals from the transmission system, and a perturbance detection system, coupled to the receiver, to measure a phase difference between a polarization of a pair of return signals of the plurality of return signals. The pair of return signals may be received from a pair of loopbacks of the plurality of loopbacks, from a first loopback and a second return signal from a second loopback. The perturbance detection system may determine a location of a perturbation, based upon the phase difference.