OTDR Multi-Step Search for Reduced Memory Optical Cable Defect Location
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Solution Overview
Problem
Optical time domain reflectometers (OTDRs) face challenges in efficiently locating defects in long optical cables due to high memory requirements, which are exacerbated by the need for small resolution distances for accurate defect identification, leading to large data samples and increased power consumption.
Innovation Solution
A multi-step search technique is employed, involving a coarse search to identify suspected defect locations and a fine search to confirm or refine them, using different sample rates and pulse widths to reduce memory needs and achieve high resolution, thereby optimizing memory and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high sample rates are used throughout the entire cable length to achieve small resolution distances, then defect location precision is improved, but memory requirements and power consumption increase significantly
Solution Approach 1:
The cable is divided into multiple segments or zones along its length. The system performs initial analysis at a lower sample rate to identify regions containing defects, then applies high sample rates only to those specific segments for precise defect location determination. This segmentation approach maintains measurement precision where needed while reducing overall memory requirements.
Solution Approach 2:
The system applies different sampling qualities to different portions of the cable. High sample rates and detailed analysis are applied locally to segments identified as containing defects, while other segments are analyzed at lower sample rates. This local quality approach ensures precise defect location identification without requiring high sample rates throughout the entire cable length, thereby reducing memory consumption.
2Measurement precision
If high sample rates are used throughout the entire cable length to achieve small resolution distances, then defect location precision is improved, but power consumption increases significantly
Solution Approach 1:
The cable is divided into multiple segments or zones along its length. The system performs initial analysis at a lower sample rate to identify regions containing defects, then applies high sample rates only to those specific segments for precise defect location determination. This segmentation approach maintains measurement precision where needed while reducing overall memory requirements.
Solution Approach 2:
The system applies different sampling qualities to different portions of the cable. High sample rates and detailed analysis are applied locally to segments identified as containing defects, while other segments are analyzed at lower sample rates. This local quality approach ensures precise defect location identification without requiring high sample rates throughout the entire cable length, thereby reducing memory consumption.
3Quantity of substance
If low sample rates are used to reduce memory requirements, then memory usage is reduced, but defect location resolution deteriorates
Solution Approach 1:
The system first performs a preliminary scan of the entire cable at a low sample rate to identify segments that contain defects. This preliminary action allows the system to locate regions of interest without requiring high memory usage. Subsequently, high sample rate analysis is applied only to these identified segments to achieve the required defect location resolution, thus balancing memory usage with measurement precision.
Solution Approach 2:
The cable is divided into multiple segments or zones along its length. The system performs initial analysis at a lower sample rate to identify regions containing defects, then applies high sample rates only to those specific segments for precise defect location determination. This segmentation approach maintains measurement precision where needed while reducing overall memory requirements.
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 reduces memory requirements and power consumption while enabling precise defect location identification in optical cables, facilitating efficient maintenance and repair by selectively using high sample rates only in targeted areas.
Implementation Method 1
Optical time domain reflectometers or OTDRs are used to locate defects in an optical cable by transmitting pulses into the cable and receiving light pulses due to Rayleigh scattering, reflection or other effects.
Implementation Method 2
The received light signal is analyzed by correlating time delays between the input signal and the reflected light signals.
Data Source
AI summary
Optical time domain reflectometer (OTDR) systems, methods and integrated circuits are presented for locating defects in an optical cable or other optical cable, in which a first optical signal is transmitted to the cable and reflections are sampled over a first time range at a first sample rate to identify one or more suspected defect locations, and a second optical signal is transmitted and corresponding reflections are sampled over a second smaller time range at a higher second sample rate to identify at least one defect location of the optical cable for relaxed memory requirements in the OTDR system.