現今無線通訊標準發展迅速，迫使業者須支付龐大的成本購買新穎的硬體設備以適應更新的通訊標準，同為無線通訊的RFID也不例外；如何迅速有效地研究與實現創新的通訊標準更是目前重要的課題。軟體無線電（Software Defined Radio, SDR）技術可以設計一個完整的通訊設備包括調製器、解調器、解碼器、編碼器等等，系統靈活性非常強大，易於實現並分析創新的演算法、通訊協定的實際效能。
本論文以LYRTECH所開發之軟體無線電（Small Form Factor Software Defined Radio, SFF SDR）實現RFID EPCglobal Class-1 Generation-2（C1G2）讀取器，以Miller code成功的對市售被動式標籤進行讀取。我們使用安捷倫訊號分析儀（Agilent N9010A EXA Signal Analyzer）及89601A VSA軟體（Agilent 89601A software Vector Signal Analyzer, VSA），量測所提讀取器接收端所接收到的標籤回傳訊號功率，統計在接收到不同功率的標籤訊號下，讀取器可以成功使標籤回傳標籤辨識碼的讀取率。
實驗結果可知，本讀取器在訊雜比大於4dB時，讀取率接近100%，當訊雜比低於4dB時，讀取率就開始往下降。
對於被動式標籤的最小需求功率為-14dBm，計算其鏈結預算（Link budget），在自由空間傳輸之反向鏈結距離大於順向鏈結距離。因此，本讀取器可適應當前RFID應用。

Due to rapid development of recent wireless communication standards, enterprises need to invest high cost on new hardware equipments to adapt standard updates. Radio frequency identification (RFID) as one kind of wireless communications is not exceptional. How to efficiently study and rapidly realize a new standard is an important issue. Software Defined Radio (SDR) technology can design a comprehensive communication device including modulator, demodulator, decoder, encoder, and so on, and is very powerful in implementing various algorithms and protocols.
This work uses LYRTECH’s Small Form Factor Software Defined Radio platform to implement an EPCglobal Class-1 Generation-2 RFID reader, which can successfully interrogate a commercial passive tag using Miller coding. We use Agilent N9010A EXA signal analyzer and Agilent 89601A software Vector Signal Analyzer to measure tag backscatter power at reader receiver end. Statistics of tag read rates in different backscatter powers are calculated based on collected data.
Experimental results show that the read rate of the reader approaches 100% when SNR is greater than 4 dB. On the other hand, the read rate decreases when SNR is less than 4 dB.
For a passive tag with the minimum power requirement as -14dBm, the free-space propagation distance of reverse link is longer than that of forward link based on link budget calculation. Consequently, the reader is sufficient for current RFID applications.

[1] EPCglobal Tag Class Structure, Nov. 2007.
[2] Radio-frequency Identification for Item Management-Part 6C: Parameters for Air Interface Communications at 860MHz to 960MHz, ISO/IEC_CD 18000-6C Standard, 2005.
[3] EPC Radio-Frequency Identity Protocols Class-1 Generation-2 UHF RFID Protocol for Communications at 860MHz-960MHz Version 1.1.0, Electronic Product Code (EPC) Standard, 2006.
[4] Ubiquitous ID Technologies, uID center, 2009. http://www.uidcenter.org
[5] D. M. Dobkin, The RF in RFID: Passive UHF RFID in Practice 1st ed. Burkington, MA:Newnes, 2007.
[6] Martin Hecht, Allan Guwa “Delay Modulation”, Proceedings of the IEEE, pp.1314-1316, July 1969.
[7] “Small Form Factor SDR Evaluation Module/Development Platform User’s Guide”, LYRTECH, 2007. http://www.lyrtech.com/
[8] “NI PXI-5600 Specification RF Vector Signal Analyzer Datasheet”, National Instruments Corportion, 2009. http://www.ni.com.tw
[9] “NI PXI-5610 Specification RF Vector Signal Analyzer Datasheet”, National Instruments Corportion, 2009. http://www.ni.com.tw
[10] 曾文信, “EPCglobal Gen2超高頻射頻辨識系統標籤FM0編碼訊號之處理,” 台灣科技大學碩士論文, 2008.
[11] Yarborough Jr., John M., “Digital Miller decoder”, United States Patent 4454499, 1981.
[12] “ALN-9540 Squiggle Inlay datasheet”, Alien Technology, Sep. 2007. http://www.alientechnology.com