Underground Optical Fiber Location via DVS Vibration Analysis
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Solution Overview
Problem
Determining the precise location and depth of underground optical fibers is challenging due to their extensive underground deployment, outdated maps, and potential for human error, which can lead to accidental damage during construction or excavation.
Innovation Solution
A method and system utilizing Distributed Vibration Sensing (DVS) and Optical Time Domain Reflectometry (OTDR) to locate underground optical fibers by generating vibration events at waypoints on a target ground surface, sending test signals through the optical fibers, and analyzing the return signals to determine the relative surface position and depth of the fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mapping methods are used to document optical fiber locations, then the system is simple and easy to operate, but the measurement precision and reliability of location data deteriorate over time due to outdated records and human error
Solution Approach 1:
The patent replaces traditional mechanical surveying and manual mapping methods with optical-based Distributed Vibration Sensing (DVS) and Optical Time Domain Reflectometry (OTDR). These optical methods use light propagation through the fiber itself to detect vibrations and determine precise location and depth, eliminating the need for complex physical surveying equipment and manual recording processes while achieving centimeter-level precision.
Solution Approach 2:
The optical fiber serves dual purposes: it functions as both the communication medium and the sensing element for location detection. The fiber itself detects vibrations caused by surface movements or excavation activities through its intrinsic optical properties, eliminating the need for separate sensing systems or external monitoring equipment.
2Measurement precision
If extensive manual surveying is performed to track numerous underground optical fibers, then location accuracy may improve, but the productivity and time required for the operation deteriorate
Solution Approach 1:
The system enables continuous monitoring of optical fiber locations and depths along entire routes rather than requiring discrete surveying at specific points. By continuously analyzing vibration signals along the fiber length, the system provides uninterrupted location data for the entire fiber path, dramatically increasing surveying efficiency while maintaining precision.
Solution Approach 2:
The optical fiber infrastructure serves multiple functions simultaneously: it acts as the communication transmission medium, the sensing element for vibration detection, and the reference path for location measurement. This multi-functionality eliminates the need for separate surveying operations and provides continuous location data for all fibers in the network.
3Reliability
If outdated maps and records are relied upon for fiber location, then the system remains simple to operate, but the reliability of avoiding accidental damage during construction deteriorates
Solution Approach 1:
The system provides real-time feedback by continuously monitoring vibration signals along the optical fiber and comparing them against the database of known fiber locations and depths. When vibrations indicate potential excavation activities, the system immediately identifies the precise location of underlying fibers and alerts operators, enabling dynamic adjustment of excavation plans to avoid damage.
Solution Approach 2:
The system performs preliminary verification by checking the database of known fiber locations before excavation activities begin. Operators can query the system in advance to obtain accurate location and depth information for planned excavation areas, allowing them to prepare appropriate avoidance measures or protective protocols before any ground disturbance occurs.
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 allows for accurate and efficient localization of underground optical fibers, reducing the risk of damage during excavation and enhancing the reliability of communication networks by providing precise geolocation data.
Implementation Method 1
performing a plurality of measurements at a plurality of waypoints of an inspection path over the target ground surface... generating a vibration event at the corresponding waypoint, concurrently to the generation of the vibration event, sending a test signal sensitive to the vibration event in the underground optical fiber
Implementation Method 2
sending a test signal sensitive to the vibration event in the underground optical fiber, and receiving a return test signal therefrom... employing a Distributed Vibration Sensing (DVS) interrogating unit optically connected to the underground optical fiber and using Optical Time domain Reflectometry (OTDR)
Data Source
AI summary
A method and a system for locating an underground optical fiber extending under a target ground surface are disclosed. The method includes performing a plurality of measurements at a plurality of waypoints of an inspection path over the target ground surface. Each measurement includes generating a vibration event at the corresponding waypoint, concurrently to the generation of the vibration event, sending a test signal sensitive to the vibration event in the underground optical fiber, receiving a return test signal therefrom and determining an amplitude of the return test signal. The method includes determining a relative surface position of a segment of the underground optical fiber crossed by the inspection path. The method includes determining a depth of the underground optical fiber by obtaining a vibration fitting curve by fitting the amplitudes of the return signals for each of the waypoints and calculating the depth of the underground optical fiber.