軟體無線電系統(Software Defined Radio, SDR)具備可重組以及多模態操作的能力而使其發展調變技術方面備受矚目；因此，利用SDR於調變技術之發展將給予3G與4G無線通訊技術前所未有的契機。本論文將利用SDR系統實現與發展數位與類比的訊號調變技術，並著重在廣泛應用於軍事與消費性通訊系統中的相位鍵移(phase shift keying, PSK)調變與正交振幅調變(quadrature amplitude modulation, QAM)技術。然而，PSK與QAM調變技術本身相較於其他調變技術於實際應用上有著更合理的誤碼率(bit error rate, BER)與參數設計。有鑑於此，分析BER於評估通訊系統的性能是必要的。本論文首先使用MATLAB分析不同數位調變技術之BER，接著將之實現於測試平台來實際驗證理論的準確性；此測試平台使用的硬體為Ettus的USRP (Universal Software Radio Peripheral)。本論文進行了部分理論的實現用以觀察訊號以及通訊系統效率的分析；實驗結果證明可程式化的SDR可解調變不同的無線電波訊號且與理論分析結果相符。

Software defined radio (SDR) is attractive for future approach in implementation of modulation techniques because of reconfigurable and multimode operation capabilities. Thus, modulation techniques based SDR is a promising approach in developing emerging wireless technologies such as 3G and 4G wireless communications. In this thesis, we design a SDR to investigate modulation techniques in both analog and digital method. Then, we focus on phase shift keying (PSK) modulation and quadrature amplitude modulation (QAM) since they are widely used in both military and commercial communication systems. Modulation techniques present themselves with specific applications according to reasonable bit error rate (BER) and other parameters when compared to other modulation techniques. Therefore, it is necessary to evaluate the performance of communication systems by analyzing BER. We first consider BER of different kinds of digital modulation techniques in theory and analyzed them by using Matlab. Next, the experimental study is performed on a test platform for a practical proof of the theory. The test platform is based on the Ettus Universal Software Radio Peripheral (USRP) hardware. Several tests are carried out to observe signals and analyze an efficiency of communication system. The results confirm that the programmed SDR can demodulate the various kinds of audio signal and also closely match the theoretical analysis.

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