改良式被動光網路的即時監控技術

An Improved Passive Optical Network for Real-Time Surveillance Technique

吳念霖(Nien-Lin Wu)

指導教授 ： 何文章

國立臺北科技大學/機電學院/光電工程系所/碩士(2007年)

摘要

本篇論文主要目標是針對傳統樹狀架構的被動光網路在傳輸時一但光鏈路發生錯誤，無法即時有效的判別故障發生位置和無法具有存活能力等缺點，所提出一套改良式被動光網路架構，主要包含了被動光網路和錯誤偵測的架構。傳輸時利用光開關切換成兩路路徑P1和P2，分別為在正常下的P1饋線光纖和發生錯誤時切換成P2保護光纖，再經2X2耦合器、分歧器和2X1耦合器，進入終端光纖，最後經分波多工耦合器和濾波器後進入光網路單元。同理上傳也依相同路徑傳輸。監控時，可利用光開關切換成兩路路徑P3和P4，分別監控饋線光纖和終端光纖。
我們針對改良式被動光網路架構做了以下實驗：(1)改良式被動光網路架構與一般被動光網路架構經過傳輸光源接收測試，把所得到兩者的接收光功率值與光譜峰值相比較，得知所減少的光功率值是因為此改良式架構額外增加兩個耦合器(1X2 Coupler 和2X2 Coupler)和多了一些連接器的損耗，但可以顯示此改良式光網路架構跟一般被動光網路的架構之光訊號功率雖有減少但損耗不大，仍可提供本實驗之偵測錯誤發生架構。(2)利用光時域反射儀進行錯誤監控，其監控錯誤發生位置分別模擬饋線光纖發生光纖彎曲損耗、終端光纖處發生連接器接點鬆落和光被動元件發生故障事件，同時針對此以上錯誤事件點進行接收光功率、眼圖和光譜圖用來辨識錯誤的發生和利用光時域反射儀偵測錯誤發生位置，其所得實驗結果皆可準確地判斷故障發生的位置，以達到即時監控與修復的功能。且此改良式架構更具有傳統被動光網路所沒有的存活能力，大大改良當任一光鏈路發生光纖斷裂或彎曲受損時，造成大量資料的中斷與流失所產生的極大營運損失等好處。

關鍵字

被動光網路 ； 錯誤偵測 ； 存活能力 ； 光時域反射儀

並列摘要

The purpose of this thesis is to improve the traditional passive optical network structure including the passive optical network and fault detecting technology. The traditional tree topology is unable to survive and discriminate the fault location immediately once the optical path encounters a mistake while transmitting. Therefore, we utilize optical switch to switch over two routes P1 and P2 which are normal feeder fiber P1 and protecting fiber P2. Signal pass P1 and P2 and through 2X2 coupler, splitter, and 2X1 coupler into the drop fiber. Finally pass through WDM coupler and filter into ONU. The upstream signal is also transmitted in the same way. We can also utilize optical switch to switch over two routes P3 and P4 to monitor the feeder fiber and drop fiber, respectively.
We have done the following experiment of improved passive optical network structure: (1) we compare the difference of the received optical power and optical spectrum of improved and traditional passive optical network structure. The optical power from our improved passive optical network structure is reduced because of the additional couplers loss (2X2 coupler and 2X1 coupler) and connector loss but the reduction is in our acceptance. Thus, the improved passive optical network can still provide the structure for fault detecting. (2) We use OTDR to monitor the fault locations which are feeder fiber bending, or connector of drop fiber loosing, or optical passive component failure. The received optical power, eye diagram, and optical spectrum are showing the fault occurrence. OTDR traces are indicating the fault locations. The results of our experiment tell the fault locations accurately which provide the functions of monitoring and restoring. Our improved passive optical network structure not only has the survival ability which is lack in the traditional passive optical network but also benefit from the loss reduction resulting from the break or bending of the optical path.

並列關鍵字

Passive Optical Network (PON) ； Fault Detection ； Survivable ； Optical Time-Domain Reflectometer(OTDR)

參考文獻

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