Fiber Event Detection Using Jones Matrix Determinant Reliability
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Solution Overview
Problem
Existing optical sensing systems for detecting fiber events in optical fibers face issues with unreliable phase extraction from Jones matrices, leading to phase artefacts and false positive detections due to fading effects, which affect the accuracy of fiber event localization and classification.
Innovation Solution
The implementation of a reliability metric based on the magnitude of the determinant of the Jones matrix is used to characterize the reliability of data derived during the optical sensing process, allowing for the selection of more reliable locations for fiber-event detection and characterization of detected events, thereby reducing false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-sensitive measurements are performed using dual-polarization optical sensing techniques, then the sensitivity and bandwidth of fiber event detection are improved, but phase artefacts and false positive detections occur due to unreliable phase extraction from Jones matrices
Solution Approach 1:
The patent introduces an intermediary reliability metric (based on the determinant of the Jones matrix) that mediates between the phase extraction process and the final detection output. This metric acts as a filter to identify and exclude unreliable measurements, thereby resolving the contradiction between maintaining high sensitivity and avoiding false positives.
Solution Approach 2:
The patent implements a feedback mechanism where the reliability metric is continuously calculated and used to adjust the detection process. When the reliability metric indicates poor quality data, the system automatically excludes those measurements from further analysis, creating a closed-loop system that maintains detection accuracy while filtering out artefacts.
2Area of stationary object
If all available locations along the optical fiber are used for fiber event detection, then the coverage and detection capability are improved, but the accuracy decreases due to inclusion of locations with unreliable data
Solution Approach 1:
The patent applies local quality by evaluating the reliability metric at each specific location along the optical fiber independently. Instead of uniformly treating all locations, the system identifies and selects only those locations where the reliability metric indicates high-quality data, thereby maintaining both broad coverage and high accuracy.
Solution Approach 2:
The patent performs preliminary evaluation of the reliability metric before conducting fiber event detection. By pre-identifying and selecting locations with reliable data, the system prepares the detection process in advance, ensuring that only high-quality locations are used for subsequent event analysis.
3Productivity
If the determinant magnitude threshold is set to include more locations for detection, then the coverage is improved, but false positive detections increase
Solution Approach 1:
The patent dynamically adjusts the determinant magnitude threshold parameter based on the specific characteristics of the optical fiber and detection conditions. By optimizing this parameter, the system achieves the right balance between including enough locations for high detection throughput and maintaining strict enough criteria to avoid false positives.
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 approach enhances the accuracy of fiber event detection by identifying suitable locations for reliable data generation and assessing the reliability of detected events, reducing misinterpretation and improving the robustness of the optical sensing system.
Implementation Method 1
Randomly distributed Rayleigh backscattering spots exist in the fiber as imperfections during its fabrication process. By capturing the optical signal that is reflected from these spots, phase changes induced by fiber events impacting a deployed fiber can be detected.
Data Source
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AI summary
In certain embodiments, an optical transceiver transmits light into an end of an optical fiber line and performs phase-sensitive (preferably OTDR) measurements of a part of the transmitted light received at the same end of the optical fiber line. A digital processor determines dual-polarization channel matrices for pairs of time and location values based on the measurements, each of the dual-polarization channel matrices describing the part of the light received in response to being passively redirected back at the time and location values of a corresponding one of the pairs. The digital processor identifies some of the location values as suitable location values for detecting fiber events along the optical fiber line based on magnitudes of determinants of the dual-polarization channel matrices determined for the location values. The magnitudes can also be used to characterize the reliability of the detected fiber events.