OTDR Signal Error Compensation via Iterative PN Sequence Feedback
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Solution Overview
Problem
The dynamic range of an optical time domain reflectometer (OTDR) is reduced due to signal distortion and noise interference when detecting optical fiber performance using multiple optical pulses, leading to reduced detection capabilities and potential service interruptions.
Innovation Solution
A method and apparatus that detect and compute compensation values for signal errors in the OTDR by comparing actual and theoretical signal sequences of pseudo-random optical pulses, allowing for real-time detection and iterative correction of optical fiber attenuation curves, thereby enhancing the OTDR's dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple optical pulses are transmitted for real-time detection, then data service continuity is maintained, but signal distortion and noise increase causing reduced dynamic range
Solution Approach 1:
The patent implements feedback by detecting the actual transmitted PN sequence at the receiving end and feeding this information back to the transmitting end. The transmitting end uses this feedback to compute compensation values that correct signal distortion, thereby maintaining both real-time detection capability and measurement precision.
Solution Approach 2:
The patent changes the parameter of the optical pulse sequence by using a pseudo-random (PN) sequence instead of single pulses, and further modifies it by applying compensation values to correct distortion. This allows real-time detection while maintaining signal integrity and dynamic range.
2Reliability
If multiple optical pulses are transmitted to avoid service interruption, then continuous monitoring is achieved, but weak reflected signals are drowned in noise
Solution Approach 1:
Feedback mechanism is used to detect the actual transmitted signal characteristics and compensate for distortion, thereby reducing noise interference while maintaining service continuity during optical fiber monitoring.
Solution Approach 2:
The patent converts the harmful effect of signal distortion and noise into a benefit by using the distorted signal itself as feedback to compute compensation values. This allows the system to learn and correct for the distortion, turning the noise problem into a solution mechanism.
3Measurement precision
If single optical pulse is transmitted to maintain signal quality, then detection accuracy is improved, but data service must be interrupted
Solution Approach 1:
The patent enables continuous optical fiber monitoring by transmitting multiple pseudo-random optical pulses without interrupting data services. The useful action of monitoring continues uninterrupted while using compensation techniques to maintain detection accuracy.
Solution Approach 2:
The patent changes from single pulse transmission to multi-pulse pseudo-random sequence transmission, and further changes by applying compensation values, thereby achieving both service continuity and detection accuracy simultaneously.
4Measurement precision
If compensation computation is performed iteratively, then detection precision is improved, but computation complexity increases
Solution Approach 1:
The patent uses iterative computation that performs partial corrections in successive steps. Each iteration provides improved accuracy, and the process can be stopped when sufficient precision is achieved, avoiding excessive computation while maintaining detection precision.
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 enables real-time detection and compensation of signal errors, improving the OTDR's dynamic range and maintaining continuous data service during optical fiber performance monitoring.
Implementation Method 1
an optical fiber produces reflection and attenuation due to Rayleigh scattering
Data Source
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AI summary
A method for compensating for a signal error at a transmit end of an optical time domain reflectometer is provided. The method includes: detecting an actual signal sequence of a PN sequence sent by a transmitter to a measured optical fiber and an actual signal sequence of an optical signal and reflected back by the measured optical fiber and received by a receiver (101); obtaining, through computation and according to the actual signal sequence of the PN sequence, a theoretical signal sequence of the PN sequence, and an optical fiber attenuation curve function obtained through an adjacent previous iterative computation, a compensation value of the optical signal that attenuates in a process in which the optical signal is reflected by the measured optical fiber (102); computing, according to the actual signal sequence of the optical signal, the compensation value, and the theoretical signal sequence of the PN sequence, an optical fiber attenuation curve function obtained through a current iteration (103); and determining, when determining that the optical fiber attenuation curve function obtained through the current iteration satisfies a given condition, performance of the measured optical fiber according to the optical fiber attenuation curve function obtained through the current iteration (104). Further, an apparatus for compensating for a signal error at a transmit end of an optical time domain reflectometer is provided.