Optical Identification Demodulation via Windowed FFT Analysis

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Solution Overview

Problem

Optical identification demodulation in WDM networks is hindered by unwanted signal disturbances caused by frequency switching in time-division multi-frequency signals, leading to inefficient demodulation and signal degradation, with existing solutions either increasing costs through additional hardware or degrading the optical signal.

Innovation Solution

The method involves partitioning the optical identification signal into windows, selecting those without frequency switching points, and performing a Fast Fourier Transform (FFT) only on these windows to avoid disturbance, thereby improving demodulation accuracy and reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If frequency switching is used in time-division multi-frequency identification signals, then channel identification capability is improved, but signal disturbance increases making demodulation difficult

Engineering Contradiction:
Improvechannel identification capabilityVSAvoidsignal disturbance
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent segments the identification signal into multiple time windows, processing each window separately through FFT analysis. This segmentation isolates frequency components within each window, allowing the system to identify channels based on frequency patterns while avoiding the disturbance caused by frequency switching between windows. The segmentation principle enables the system to maintain identification capability while mitigating signal disturbance through localized processing.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If additional hardware is added to solve frequency switching disturbance, then demodulation accuracy is improved, but system cost increases

Engineering Contradiction:
Improvedemodulation accuracyVSAvoidsystem cost
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex hardware solutions with a computational approach using Fast Fourier Transform (FFT) algorithms processed on existing signal data. Instead of adding physical hardware components to filter or compensate for frequency switching disturbances, the system uses mathematical transformation and signal processing techniques to achieve accurate demodulation. This substitution of mechanical/hardware solutions with computational methods maintains demodulation accuracy while reducing system cost and complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Loss of information

If frequency switching points are included in the signal for identification, then identification signal completeness is improved, but noise and interference increase during demodulation

Engineering Contradiction:
Improveidentification signal completenessVSAvoidnoise and interference
Core Design Contradiction:
Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and separates frequency components within each time window using FFT analysis, allowing the system to identify channels based on the frequency patterns present in each window. By extracting frequency information locally within each window rather than processing the entire signal including frequency switching points, the system maintains identification signal completeness while removing the noise and interference introduced by frequency transitions. The extraction principle enables selective processing that preserves useful identification information while eliminating harmful disturbances.

Inventive Principle:
Principle #2Taking out (Extraction)

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 effectively mitigates the impact of frequency switching, enhances signal-to-noise ratio, and provides a cost-effective solution for accurate optical channel identification in WDM networks.

Implementation Method 1

performing a Fast Fourier Transform (FFT) on each of the plurality of windows, determining which of the plurality of windows comprise a relative minimum number of frequency components

Methodology Applied
Scientific EffectFast Fourier Transform:

Data Source

PatentUS7603034B2Optical identification demodulation method and system
Publication Date: 2009.10.13 HUAWEI TECH CO LTD
  • US7603034B2 patent drawing
  • US7603034B2 patent drawing
  • US7603034B2 patent drawing

AI summary

A telecommunications network component comprising: a processor configured to implement a method comprising: receiving an optical signal comprising at least one identification signal, the identification signal comprising a series of frequency portions that alternate in turn according to a frequency interval defined for each of the series of frequency portions, partitioning the identification signal by way of a plurality of windows, performing a Fast Fourier Transform (FFT) on each of the plurality of windows, determining which of the plurality of windows comprise a relative minimum number of frequency components, and detecting an optical channel based on results of the FFT performed on each of the plurality of windows that comprise the relative minimum number of frequency components.