臺灣博碩士論文加值系統

免手持通訊系統的應用有免手持聽筒電話、視訊會議、遠距教學及遠端醫療等系統，此種通訊系統必需解決聲學迴音之問題。可適性濾波器提供這個問題的有效解決方法。
首先本篇論文介紹適應演算法LMS家族與聲學迴音消除架構，進而以德州儀器的TMS320C32的浮點DSP處理器，實現適應演算法的NLMS與MDF應用在聲學迴音消除上。最後我們將這些演算法在實作方面作實際的運算量分析、比較。我們發現NLMS演算法架構簡單而且容易實現，適合短迴音路徑。MDF演算法其架構較為複雜，但是對於長迴音路徑，有其運算量少的優勢。

Hands-free communications system finds applications in hands-free phone, video conferencing system, and distance learning/medicine system. Adaptive filtering algorithm provides an effective means for solving the acoustic echo problem associated with such system.
In this thesis, we briefly review the algorithms of LMS family. The acoustic echo cancellation configuration is then presented. We implement the normalized LMS and the MDF algorithm with Texas Instruments TMS320C32 floating DSP processor. Finally, we study and analyze the number of operations required in implementation. Our study shows that the NLMS algorithm is simple in structure, easy to implement, and suitable for short echo path applications. The MDF algorithm is quite complicated, however, it is very fast in the long echo path applications.

中文摘要i
英文摘要ii
致謝iii
目錄………….iv
圖目錄vi
表目錄viii
第一章簡介1
1.1背景介紹1
1.2論文組織4
第二章適應演算法之介紹5
2.1簡介5
2.2NLMS演算法(Normalized Least-Mean-Square Algorithm)5
2.3Block LMS 演算法(Block Least-Mean-Square Algorithm)7
2.4FBLMS 演算法(Frequency Domain Block LMS)9
2.5MDF 演算法(Multidelay Block Frequency Domain LMS Algorithm)
13
2.6結論16
第三章以DSP與NLMS為基礎之迴音消除系統研究與實作19
3.1DSP軟硬體的環境簡介19
3.2聲學迴音消除的基本架構26
3.3NLMS演算法的核心程式29
3.4實驗結果分析32
3.5計算量分析與討論36
3.6系統展示40
第四章以DSP與MDF為基礎之迴音消除系統研究與實作41
4.1 MDF演算法的核心程式41
4.2 實驗數據分析44
4.3計算量分析與討論49
4.4系統展示55
第五章結論56
參考文獻 57

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