在超高頻被動式射頻辨識系統裡，讀取器傳送未調變過之連續波訊號給標籤，其不但可提供能量給標籤也作為標籤反向散射訊號的載波。此連續波通常比標籤回傳訊號強，因此會覆蓋掉微弱的標籤反向散射訊號，並且導致不可回覆的解調錯誤。
本論文採用EPCglobal Gen2 標籤對讀取器通訊流程的Preamble訊號(經過FM0編碼)來同步標籤回傳訊號，並偵測連續波訊號，接著將連續波訊號消除以增強標籤反向散射訊號。
藉由在無反射實驗室所做的量測，得到不同訊號雜訊比的通訊訊號，並用此實驗結果驗證本論文之方法。此實驗結果將與理論值做比較，且探討造成兩者差異之原因。

In a UHF passive RFID system, a reader transmits an unmodulated continuous wave (CW) to tags, which not only provides energy to tags but also serves as the carrier of tag backscatter signals. The CW usually overwhelms the weak tag backscatter signals, and leads to unrestorable demodulation errors.
In this thesis, the FM0 encoded preamble signals in the EPCglobal Gen2 tag-to-reader link is used to acquire the synchronization of tag responses, and to estimate the unmodulated CW. The CW is then suppressed to enhance the tag backscatter signals.
Experimental results with various signal-to-noise ratios taken in microwave anechoic chamber are used to verify the scheme. The empirical results are compared with theoretical results, and the differences are discussed.

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