Optical Fiber Dispersion Measurement Using Supervisory Channel Signals
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Solution Overview
Problem
Current methods for measuring the dispersion coefficient of optical fibers in WDM systems are inefficient and costly, requiring physical removal of fibers for measurement, leading to labor-intensive and error-prone processes.
Innovation Solution
A method using a network device to generate and send optical supervisory channel measurement signals with different wavelengths through optical fibers, determining the delay difference between these signals to calculate the dispersion coefficient without damaging the fibers, thereby improving measurement efficiency and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fiber is removed from the WDM system for measurement, then dispersion coefficient can be measured, but measurement time and labor cost increase significantly
Solution Approach 1:
The optical fiber transmission system performs self-measurement of dispersion coefficient using its own existing components (optical time domain reflectometer, supervisory channel) without requiring external measurement equipment or fiber removal. The system uses bidirectional transmission of test signals through the fiber link to calculate dispersion based on time delay differences.
Solution Approach 2:
The supervisory channel and optical time domain reflectometer, originally designed for other functions (monitoring, fault detection), are utilized to also perform dispersion coefficient measurement. This multi-functional approach eliminates the need for dedicated measurement equipment and fiber removal.
2Measurement precision
If optical fiber is removed from the WDM system for measurement, then dispersion coefficient can be measured, but measurement cost increases
Solution Approach 1:
The system uses its own existing components (optical time domain reflectometer, supervisory channel, bidirectional transmission capability) to perform self-measurement, eliminating the need for external measurement equipment, fiber removal, and specialized personnel, thereby significantly reducing measurement cost.
Solution Approach 2:
Existing components are made multi-functional by using them for both original purposes and dispersion measurement. The optical time domain reflectometer and supervisory channel handle both monitoring and measurement tasks, avoiding additional hardware costs.
3Measurement precision
If optical fiber is removed from the WDM system for measurement, then dispersion coefficient can be measured, but operational complexity increases
Solution Approach 1:
The measurement process is automated within the system itself, requiring no manual fiber handling, connection/disconnection operations, or coordination between multiple teams. The system automatically transmits test signals, measures time delays, and calculates dispersion coefficients.
Solution Approach 2:
The mechanical process of fiber removal and physical connection is replaced by an optical/electrical signal-based measurement process. Test signals are transmitted through the existing optical link, and dispersion is calculated based on time delay differences, eliminating all mechanical manipulation of fibers.
4Measurement precision
If optical fiber is removed from the WDM system for measurement, then dispersion coefficient can be measured, but transmission service is disrupted
Solution Approach 1:
The system performs measurement during normal operation without requiring fiber removal or service interruption. The bidirectional transmission of test signals through the existing fiber link allows dispersion measurement while maintaining continuous transmission services.
Solution Approach 2:
The measurement process uses periodic transmission of test signals through the fiber link in both directions. These periodic signals are superimposed on the normal transmission traffic, allowing measurement without disrupting ongoing services while continuously monitoring dispersion characteristics.
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 dispersion coefficient measurement without disrupting the optical fibers, reducing labor and costs, and enabling more efficient network planning and maintenance.
Implementation Method 1
Different types of optical fibers have different core diameters, dispersion coefficients, dispersion slopes, zero-dispersion wavelengths, and the like. As a result, transmission of a WDM system has different nonlinear effects.
Implementation Method 2
US 2009/279890 A1 describes a method of determining an optical distance between two nodes of an optical network for chromatic dispersion compensation includes using existing optical supervisory channel components in each node to measure the 'time-of-flight' of an optical signal having a known wavelength.
Data Source
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AI summary
Embodiments of the present invention disclose a method for measuring a dispersion coefficient of an optical fiber, to improve measurement efficiency and reduce measurement costs. The method in the embodiments of the present invention includes: sending, by a network device, a first optical supervisory channel OSC measurement signal and a second OSC measurement signal, where wavelengths of the first OSC measurement signal and the second OSC measurement signal are different; receiving, by the network device, the returned first OSC measurement signal and second OSC measurement signal, where the first OSC measurement signal and the second OSC measurement signal are transmitted through a first optical fiber and a second optical fiber to return to the network device, and the first optical fiber and the second optical fiber are a to-be-tested optical fiber; determining, by the network device, a delay difference between the received first OSC measurement signal and second OSC measurement signal; and determining, by the network device, a dispersion coefficient of the to-be-tested optical fiber based on the delay difference. The embodiments of the present invention further provide a network device. The embodiments of the present invention can improve measurement efficiency, reduce labor use and optical fiber loss, and reduce measurement costs.