PON Diagnostic Apparatus for Accurate Long Extension Function Assessment
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Solution Overview
Problem
The existing PON systems face challenges in accurately determining the need for a long extension function during accommodation station relocation due to varying waveform distortion caused by wavelength dispersion, leading to unnecessary upgrades and increased costs.
Innovation Solution
A diagnostic apparatus and method that measure the center wavelength and spectrum width of each ONU's signal, compare these against an allowable line length list, and determine whether system updates are necessary based on transmission distances, thereby accurately assessing the need for long extension functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If FP-LD is used in ONU transmitter for cost reduction, then device cost is reduced, but waveform distortion increases due to wavelength dispersion at long-distance transmission
Solution Approach 1:
The invention changes the evaluation parameter from fixed specification-based judgment to dynamic spectrum-based judgment. By measuring the actual center wavelength and spectrum width of each ONU's transmitted signal, the system determines waveform distortion characteristics specific to each device, enabling accurate identification of which ONUs actually require long extension functions.
2Length of stationary object
If long extension function is implemented for all ONUs during relocation, then transmission distance capability is improved, but system cost increases due to unnecessary upgrades
Solution Approach 1:
The invention applies local quality by treating each ONU individually based on its measured spectral characteristics. Instead of uniformly upgrading all ONUs, the system identifies specific ONUs with narrow spectrum width that are susceptible to waveform distortion, and only these devices are equipped with long extension functions. This localized approach ensures transmission distance capability is improved only where necessary, avoiding unnecessary system costs.
3Length of stationary object
If DFB-LD with enhanced transmission output is used in long-distance ONU, then transmission distance is extended, but device cost increases compared to FP-LD
Solution Approach 1:
The invention changes the selection criterion from distance-based to spectrum-based. By measuring the center wavelength and spectrum width of each ONU, the system identifies devices with narrow spectral width that are prone to waveform distortion. Only these specific devices are upgraded to DFB-LD with enhanced transmission output, while other ONUs continue to use cost-effective FP-LD, achieving transmission distance extension only where spectrally necessary.
4Measurement precision
If APD with high reception sensitivity is used in long-distance ONU, then reception sensitivity is improved, but device cost increases due to expensive power source circuit
Solution Approach 1:
The invention applies local quality by equipping only specific ONUs with APD receivers. Based on measured spectrum width, the system identifies ONUs with narrow spectrum that are susceptible to waveform distortion and require enhanced reception sensitivity. These specific devices are equipped with expensive APD and high-voltage power source circuits, while other ONUs use simpler PIN-PD receivers, achieving reception sensitivity improvement only where spectrally necessary.
Data Source
AI summary
In response to the above issue, an object of the present invention is to provide a diagnostic apparatus and a diagnostic method capable of accurately recognizing whether to use a long extension function at the time of relocation of an accommodation station of an OLT. The diagnostic apparatus according to an aspect of the present invention has an allowable line length list that is a relationship between a center wavelength and an allowable line distance that satisfies a selected spectrum width in an optical fiber used in an optical communication system, measures a center wavelength and a spectrum width of a spectrum for each ONU, matches the allowable line length list, and obtains an allowable line distance of each ONU.