OTDR Signal Processing Using Dual Pulse Width Segmentation
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Solution Overview
Problem
Conventional optical time-domain reflectometers face a tradeoff between dead zone performance and dynamic range, where reducing pulse width improves dead zone performance but results in a low signal-to-noise ratio (SNR) in backscatter regions, making backscatter data unreliable.
Innovation Solution
An optical time-domain reflectometer emits two impulse light signals with different pulse widths, one shorter and one longer than the optical fiber, and processes the reflected signals using a difference filter to generate an optical fiber response signal, combining segments to enhance dynamic range and SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pulse width of the transmitted optical signals is decreased to improve dead zone performance, then the dynamic range is reduced, resulting in a low signal-to-noise ratio in backscatter regions
Solution Approach 1:
The invention divides the optical fiber testing into two separate measurements: one using a short pulse width for dead zone performance and another using a long pulse width for dynamic range. The final response is constructed by combining segments from both measurements, with the short pulse data used for regions requiring dead zone performance and the long pulse data used for regions requiring dynamic range, thereby resolving the contradiction between these two performance metrics.
Solution Approach 2:
The invention changes the pulse width parameter between two separate measurements. The first measurement uses a first pulse width optimized for dead zone performance, while the second measurement uses a second pulse width optimized for dynamic range. By varying this critical parameter across different measurements and selectively combining the results, the system achieves both improved dead zone performance and maintained signal-to-noise ratio.
2Ease of operation
If the pulse width is decreased to mitigate dead zones, then the dynamic range decreases, making backscatter data unreliable
Solution Approach 1:
The invention segments the optical fiber response into different regions that are measured using different pulse widths. Regions requiring dead zone mitigation are measured with short pulses, while regions requiring reliable backscatter data are measured with long pulses. The final composite response seamlessly integrates these segments, ensuring both dead zone mitigation and backscatter data reliability are achieved in their respective regions.
Solution Approach 2:
The processor acts as an intermediary that receives data from two separate measurements taken with different pulse widths and combines them into a single composite response. This intermediary processing step allows the system to leverage the advantages of both short and long pulse measurements, assigning each segment to the appropriate pulse width data based on the specific requirements of that region.
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 improves the signal-to-noise ratio over the entire range of the reflectometer's response, providing reliable backscatter data while maintaining effective dead zone performance.
Implementation Method 1
a photodetector configured to receive the third light signal and the fourth light signal output by the optical device and to convert the third light signal and the fourth light signal to a first electronic signal and a second electronic signal, respectively
Data Source
AI summary
An optical time-domain reflectometer (OTDR) is provided. The OTDR emits a first optical signal that is an impulse optical signal having a non-zero power during a first period of time, where the first period of time is shorter than a period of time necessary for the first optical signal to traverse a length of an optical fiber under test. The OTDR emits a second optical signal that is an impulse optical signal having a non-zero power during a second period of time longer than a period of time necessary for the second optical signal to traverse the length of the optical fiber. The OTDR receives data representative of a third and fourth optical signals that are reflections of the first and second optical signals, respectively, by the optical fiber and generates an optical time-domain reflectometry signal based at least in part on the third and fourth optical signals.