Optical Fiber Defect Detection Using Data Wavelength OTDR
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Solution Overview
Problem
Existing optical fiber communication systems with integrated OTDR functionality face challenges such as high cost, reduced accuracy due to nonlinearity of amplifiers, and mismatched operating wavelengths between data and OTDR signals, which affect defect detection in fiber optic cables.
Innovation Solution
The system integrates OTDR functionality by using the data transmitter's signals at the data wavelength for OTDR operations, optimizing the amplifier linearity and reducing noise through continuous data variation and cross-correlation averaging, while employing a WDM coupler for simultaneous data and OTDR signal transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate OTDR is used for defect detection when the fiber is not being used for communication, then defect detection capability is provided, but system complexity and cost increase
Solution Approach 1:
The patent combines OTDR functionality with the existing data communication system by using the same optical fiber infrastructure. The data transmitter's PRBS signal is repurposed for OTDR measurements, eliminating the need for a completely separate OTDR device while maintaining defect detection capability.
Solution Approach 2:
The patent makes the data communication system multi-functional by enabling it to perform both data transmission and OTDR defect detection. The PRBS signal generated for data communication is also used as the test signal for OTDR measurements, allowing one system to serve multiple purposes.
2Productivity
If OTDR functionality is integrated into the fiber optic communication system with multiple wavelengths, then simultaneous defect detection and communication are enabled, but interference between optical signals increases
Solution Approach 1:
The patent converts the potentially harmful PRBS signal that would normally interfere with OTDR measurements into a beneficial element by using it as the OTDR test signal itself. The same PRBS signal used for data communication is repurposed to provide the test sequence for defect detection, turning what would be interference into the measurement signal.
Solution Approach 2:
The patent changes the operational parameters by using the data wavelength for OTDR measurements instead of a separate third wavelength. This parameter change eliminates the need for additional wavelength management and reduces interference while maintaining simultaneous operation capability.
3Object-affected harmful factors
If OTDR operates at a third wavelength to minimize interference, then signal interference is reduced, but amplifier linearity and measurement accuracy deteriorate due to nonlinearity at different wavelengths
Solution Approach 1:
The patent changes the wavelength parameter from a third wavelength to the data wavelength itself. This parameter change ensures that the OTDR measurements are performed at the same wavelength where the amplifier is optimized for linear operation, thereby improving measurement accuracy while still using the PRBS signal for OTDR functionality.
Solution Approach 2:
Instead of using a separate third wavelength to avoid interference, the patent inverts the approach by using the data wavelength itself for OTDR measurements. This inversion eliminates the wavelength mismatch problem and allows the system to operate at the wavelength where the amplifier provides optimal linearity.
4Productivity
If multiple optical signals at different wavelengths are transmitted simultaneously using WDM, then communication capacity increases, but the cost and complexity of wavelength management increases
Solution Approach 1:
The patent makes the existing WDM system multi-functional by enabling the data communication signals to also serve as OTDR test signals. This eliminates the need for additional dedicated OTDR wavelengths and simplifies wavelength management while maintaining high communication capacity.
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 costs, improves accuracy by operating at the data wavelength, and minimizes noise and linearity effects, enhancing defect detection in optical fiber cables.
Implementation Method 1
The transmitted and received data signals are combined using a WDM coupler 212. All data signals and OTDR signals pass through a coupler 216 for simultaneous transmission and reception along an optical fiber 218.
Implementation Method 2
The OTDR receiver 206 detects optical signals at the first wavelength λ1 using a photo diode 214.
Data Source
AI summary
An optical data transmitter is operable to transmit data other than test data on an optical fiber at a first wavelength and an optical time domain reflectometer is operable to receive data from the optical fiber at the first wavelength and to use the received data at the first wavelength to determine whether a defect exists in the optical fiber.