Optical Module Asymmetry Detection via Pulse Time Delay

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Solution Overview

Problem

Current methods for addressing bidirectional asymmetry in optical fibers, which cause significant time errors in 1588 time synchronization technology, are inefficient and inaccurate, particularly in large-scale network deployments, due to high complexity and slow response times.

Innovation Solution

A synchronization system and method that includes a master and slave optical module device with a pulse asymmetry detection unit and time delay compensation unit to detect pulse transmission time delay differences and asymmetry distances, allowing for quick and accurate calculation of asymmetry time delays and subsequent time synchronization corrections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If OTDR technology is used for measuring optical fiber asymmetry, then measurement capability is achieved, but measurement time increases and execution complexity increases causing slow response

Engineering Contradiction:
Improveoptical fiber asymmetry measurementVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts the asymmetry detection function from complex OTDR technology and implements it directly in the optical module using a simplified pulse transmission method. The optical module sends detection packets and measures round-trip time differences locally, eliminating the need for external OTDR equipment and reducing measurement complexity while maintaining measurement capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces detection packets as intermediaries to measure optical fiber asymmetry. Instead of using complex OTDR technology, the system sends standardized detection packets through the optical fiber and measures the round-trip time differences. These packets act as mediators that enable asymmetry measurement through simple time comparison, significantly reducing measurement time and execution complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If OTDR technology is used for measuring optical fiber asymmetry, then measurement capability is achieved, but execution complexity increases causing slow response

Engineering Contradiction:
Improveoptical fiber asymmetry measurementVSAvoidexecution complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential measurement function from OTDR technology and implements it natively in the optical module. By using built-in pulse transmission and time measurement capabilities, the system eliminates complex external measurement equipment and reduces execution complexity while maintaining measurement precision through direct round-trip time comparison.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The optical module performs asymmetry detection on its own using self-contained resources. The module sends detection packets through its own transmission interface and measures round-trip times using its internal clock, eliminating dependency on external OTDR equipment. This self-service approach significantly reduces execution complexity and enables faster response.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If point-by-point compensation is performed during network construction, then asymmetry correction is achieved, but network construction efficiency decreases

Engineering Contradiction:
Improveasymmetry correction accuracyVSAvoidnetwork construction efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent implements asymmetry detection and compensation automatically during the network construction phase. The system detects optical fiber asymmetry and calculates compensation values before normal service traffic is established. By performing this correction preliminarily, the system avoids the need for manual point-by-point compensation later, significantly improving network construction efficiency while maintaining correction accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements automatic feedback loops for asymmetry compensation. The system continuously monitors round-trip time differences, automatically calculates compensation values, and applies corrections to maintain synchronization accuracy. This automated feedback mechanism eliminates manual intervention, improving both construction efficiency and operational reliability.

Inventive Principle:
Principle #23Feedback

4Measurement precision

If optical fibre changeover is performed through an optical switch, then asymmetry correction is achieved, but service damage may occur and compatibility with existing devices is difficult

Engineering Contradiction:
Improveasymmetry correctionVSAvoidservice continuity
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent extracts the asymmetry correction function from external optical switching mechanisms and implements it within the optical module itself. By using built-in detection and compensation capabilities, the system corrects asymmetry without requiring service interruption or optical switch operations, ensuring continuous service and better compatibility with existing devices.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The optical module performs asymmetry correction on its own without requiring external optical switches or service interruption. The module detects asymmetry through its own transmission interface and applies compensation internally, maintaining service continuity and avoiding the reliability issues associated with optical switch-based changeover methods.

Inventive Principle:
Principle #25Self-service

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 detection time, lowers execution complexity, and improves accuracy, enabling faster and more reliable time synchronization in optical fiber networks.

Implementation Method 1

detect the pulse transmission time delay difference and the asymmetry distance of the bidirectional optical fibres

Methodology Applied
Scientific EffectTime of Flight: Time of Flight

Implementation Method 2

constitute a distance measurement system by Rayleigh scattering and backscattering formed by Fresnel reflection during the transmission of optical pulses

Methodology Applied
Scientific EffectRayleigh scattering: Rayleigh Scattering

Implementation Method 3

backscattering formed by Fresnel reflection during the transmission of optical pulses

Methodology Applied
Scientific EffectFresnel reflection: Fresnel Lens

Data Source

PatentEP2924889B1Synchronization system, method and master/slave optical module device for detecting asymmetry of optical fiber
Publication Date: 2019.08.21 ZTE CORP
  • EP2924889B1 patent drawingFigure 1~2
  • EP2924889B1 patent drawingFigure 3~4
  • EP2924889B1 patent drawingFigure 5

AI summary

A synchronization system for detecting asymmetry of optical fibres is provided, which includes a time synchronization correction device, a time delay compensation unit and an optical module device, wherein the optical module device is configured to detect a pulse transmission time delay difference and an asymmetry distance of bidirectional optical fibres between network elements on two sides and to obtain an asymmetry time delay of the bidirectional optical fibres according to the asymmetry distance of the bidirectional optical fibres and the pulse transmission time delay difference. A synchronization method for detecting asymmetry of optical fibres is also provided, which includes obtaining an asymmetry time delay of bidirectional optical fibres according to an asymmetry distance of the bidirectional optical fibres and a pulse transmission time delay difference. A master optical module device and a slave optical module device for detecting asymmetry of optical fibres are also provided.