臺灣博碩士論文加值系統

早產兒由於身體發育尚未成熟即出生，因此必須暫時在保溫箱中生長，並且受到一些儀器如呼吸器、心電圖儀與腦波儀等輔助並監視生理功能，然而這些儀器再加上醫院的警報器、對講機所發出的聲音將會對保溫箱內的早產兒產生干擾，造成不安。為避免保溫箱內早產兒受到噪音影響，因此在本論文中採行主動式噪音控制(ANC)方法，採用1×2×2單參考/多輸出之多通道FXLMS演算法，以早產兒頭部產生靜音區為概念，降低噪音影響。
本系統使用Real-time windows target在PC底下進行控制器運作，並搭配訊號感測電路、放大電路、處理電路、制動器電路及擷取電路等構成ANC系統。
在測試上，由訊號產生器產生幾種不同的訊號送至揚聲器，模擬保溫箱內噪音，實驗結果可以得知，誤差麥克風與揚聲器的擺放位置將會對消音效能有所影響外，多通道的消音效果可以達到數dB，甚至數十dB以上。

There is much acoustic noise around the incubators, including the sounds of the medical instruments, the rings of the intercoms, alarms etc. The acoustic noises will affect premature infants in the incubators, and cause disquiet in them. In order to make the premature infants living in a quiet environment, noises in the incubators needs to be removed. In this paper, we use ANC method and adopt 1×2×2 multi-channel FXLMS algorithm to build a quiet zone around the premature infant’s head.
The ANC controller is PC-based, using real-time windows target to implement the algorithm. Pure sine waves, square waves, and amplitude-modulated (AM) waves were used as the noise sources in the incubator. Results show that noise can be substantially reduced.

第一章 簡介 1
1-1 研究動機 1
1-2 研究方式 1
1-3 章節題要 2

第二章 背景理論與相關論文研究 3
2-1 ANC基本原理 3
2-2 適應性演算法 4
2-3 LMS演算法 7
2-4 NLMS演算法 9
2-5 Leaky LMS演算法 9
2-6 FXLMS演算法 10
2-7 單參考/多輸出之多通道LMS演算法 12

第三章 系統設計與實現 16
3-1 實驗裝置與設備 16
3-1-1 麥克風放大電路 18
3-1-2 低通濾波器設計 18
3-1-3 NI PCI-6024E資料擷取卡 19
3-2 軟體設計 20

第四章 實驗結果與討論 23
4-1 第二路徑轉移函數之估計 23
4-2 單通道FXLMS演算法實驗結果 25
4-2-1 模擬噪音源：300Hz正弦波 25
4-2-2 模擬噪音源：300Hz調幅弦波 28
4-2-3 模擬噪音源：300Hz方波 31
4-2-3 模擬噪音源：300Hz調幅方波 31
4-3 單參考/多輸出之多通道FXLMS演算法實驗結果 36
4-3-1 模擬噪音源：300Hz正弦波 36
4-3-2 模擬噪音源：300Hz調幅弦波 36
4-3-3 模擬噪音源：300Hz方波 39
4-3-3 模擬噪音源：300Hz調幅方波 39

第五章 結論與未來展望 42

參考文獻 43

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2.P. A. Nelson and S. J. Elliott, Active Control of Sound, Academic Press, New York, 1992.
3.白明憲，聲學理論與應用-主動式噪音控制-，全華科技圖書股份有限公司，1999。
4.張錦松與韓光榮，噪音振動控制，高立圖書有限公司，1993。
5.S. J. Elliot and P. A. Nelson, ”Active noise control,” IEEE Signal Processing Magazine, pp.12-35, Oct. 1993.
6.V. V. Krishna, Adaptive Filtering Theory and Applications.
7.陳克任與黃永發，數位信號處理，全威圖書有限公司，2000。
8.D. H. Crawford, R. W. Stewart and E. Toma, “Digital signal processing strategies for active noise control.”, Electronics & Communication Engineering Journal, Apr. 1997.
9.Y. C. Park and S. D. Sommerfeldt, “A fast adaptive noise control algorithm based on the lattice structure,” Applied Acoustics, 47, Jan. 1996.
10.S. C. Douglas, “Fast implementations of the filtered-X LMS and LMS algorithms for multichannel active noise control,” Speech and Audio Processing, IEEE Transactions on , vol. 7 Issue: 4 , pp.454-465, Jul. 1999.
11.M. Zhang, H. Lan, and W. Ser, “An improved secondary path modeling method for active noise control systems,” IEEE Signal Processing Letters, vol. 7, pp.73-75, Apr. 2000.
12.M. Zhang, H. Lan, and W. Ser, “Cross-updated active noise control systems with online secondary path modeling,” IEEE Trans. Speech Audio Processing, vol. 9, pp.598-602, Jul. 2001.
13.M. Zhang, H. Lan, and W. Ser, “An active noise control systems using online secondary path modeling with reduced auxiliary noise,” IEEE Signal Processing Letters, vol. 9, pp.16-18, Jan. 2002.
14.C. Bao, P. Sas, and H. Van Brussel, “Comparison of two online identification algorithms for active noise control,” in Proc. Recent Advances in Active Control of Sound Vibration, 1993, pp. 38-51.
15.P. Joseph, S. Elliott, and P. Nelson, “Near field zones of quiet,” Journal of Sound and Vibration, 172(5), pp.605-627, 1994.
16.H. D. Nam, S. K. Hong, and K. Han, “Active control of noise in an enclosure using hybrid control techniques”, Information, Communications and Signal Processing, Sept. 1997, vol.2, pp.758 -761.
17.D. R. Morgan and D. A. Quinlan, “Local silencing of room acoustic noise using broadband active noise control” in Proc. 1993 IEEE SP Workshop on Applications of Signal Processing to Audio and Acoustic, pp. 23-25, 1993.
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