A method for distinguishing and estimating the distance of adjacent fault points of an OTDR

By using an OTDR adjacent fault point discrimination and spacing estimation method, the problem of difficulty in identifying adjacent fault points under long distance and large dynamic range of OTDR is solved, and the accurate discrimination and spacing estimation of adjacent fault points are achieved, thereby improving the stability and accuracy of fault detection.

CN122372072APending Publication Date: 2026-07-10JILIN UNIVERSITY
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
JILIN UNIVERSITY
Filing Date
2026-05-14
Publication Date
2026-07-10

AI Technical Summary

Technical Problem

Existing OTDR technology has difficulty accurately identifying and estimating the number and spacing of adjacent fault points under long-distance detection and large dynamic range testing conditions. In particular, when the fault points are close together, their responses tend to overlap, making it difficult for existing methods to reliably determine the number of fault points and the location offset.

Method used

An OTDR adjacent fault point discrimination and spacing estimation method is adopted. By collecting the OTDR backscatter curve of the fiber optic link, and combining the finite pulse width and bandwidth characteristics, a local physical model is established, baseline removal is performed, and parameter estimation is carried out using the least squares method and variable projection method. The Bayesian information criterion is used for model selection to determine the number of fault points and estimate the spacing.

Benefits of technology

It improves the resolution and positioning accuracy of OTDR in adjacent fault point detection, can accurately distinguish between single and double faults when fault responses overlap, reduces computational complexity, and is suitable for fiber optic link analysis in long-distance and complex fault scenarios.

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Abstract

This invention relates to the field of optical fiber communication testing technology, specifically a method for distinguishing adjacent fault points and estimating the distance between them using an OTDR. The method first acquires the OTDR backscattering curve of the optical fiber link under test, and then locates the starting position of the first fault point through preprocessing. Within a local analysis window, single-fault and double-fault physical models considering the system's finite pulse width and bandwidth characteristics are established. After baseline removal processing of the local observation signal, the optimal parameters of the two models are estimated using ordinary least squares and variable projection methods, respectively. Then, model selection is performed based on the Bayesian information criterion to determine the number of fault points, and when a double fault is identified, the estimated distance between the two fault points is output. This invention solves the problem of accurately distinguishing the number and estimating the distance between adjacent fault points when their responses overlap, significantly improving the OTDR's ability to distinguish and locate nearby fault points. It has high computational efficiency, good robustness, and is suitable for long-distance, large dynamic range optical fiber link testing scenarios.
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