同時傳輸數位與射頻訊號在光纖連結下之研究

Study of Simultaneous Transmission of Digital and RF Signals over Fiber-Optic Links

鄭茗仁(Ming-Jen Cheng)

指導教授 ： 詹益仁

國立中央大學/資訊電機學院/電機工程學系/碩士(2007年)

摘要

光纖可用來承載多媒體信號如影音和資料並結合次載波多工技術傳遞數位信號。因此，光纖射頻在有線及無線寬頻擷取技術上扮演一關鍵的角色。在本論文中，將探討利用光纖同時傳遞1.25Gb/s的數位訊號及2.4GHz的射頻訊號，分別就光域及電域比較兩種解調機制。另外，也比較了訊號的結合方式。當數位與射頻訊號同時輸入至單一MZM時，在接收光功率為-17.67dBm的情況下，使用光域解調方式的位元錯誤率為6.5x10-8，相位差為3.1°。使用電域解調方式的位元錯誤率為3.1x10-7，相位差為5.1°。由結果得知，在數位訊號及射頻訊號的解調表現上，光域解調方式的位元錯誤率較電域解調方式的位元錯誤率提升了近一個數量級，而相位差提升了2°，說明了光域的解調方式訊號失真較不嚴重，因此在位元錯誤率與相位差較小。而利用兩個並聯的MZM，分別將數位訊號與射頻訊號個別輸入至兩個MZM，亦即數位訊號與射頻訊號在光域做結合時，在接收光功率為-17.67dBm的情況下，在光域解調的位元錯誤率為8x10-9，相位差為2.2°。而在電域解調的位元錯誤率為5x10-8，相位差為4.5°。由結果得知，在數位訊號及射頻訊號的解調表現上，當訊號在光域作混合其位元錯誤率較在電域做混合時，位元錯誤率提升了近一個數量級，而相位差方面，在光域解調與電域解調分別提升了0.9°及0.6°。由此得知，數位訊號與射頻訊號在光域作結合其解調表現較電域做結合來的佳。

關鍵字

馬赫詹德調變器 ； 射頻光纖

並列摘要

In all access networks, optical fiber plays an imperative role. Fiber carries multimedia signals such as video, audio and data with a combination of subcarrier multiplexed radio over fiber and digital baseband formats. Therefore, radio over fiber plays key role in both wired and wireless broadband multimedia access networks. In this thesis, a simultaneous modulation and fiber-optic transmission of 1.25Gb/s digital signal and 2.4GHz RF signal with Gaussian minimum shift keying(GMSK) data is investigated. We compare two demodulation schemes which demodulate single digital signal and multiple radio channels in optical and electrical domain. In addition, we also compare two combination schemes which combine single digital signal and multiple radio channels in optical and electrical domain. The optimum operating conditions for digital signal and multiple radio channels are also investigated.

並列關鍵字

mach zehnder modulator ； radio over fiber

參考文獻

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