摘要
本論文致力於消除電腦軸流式風扇所產生的噪音，運用了主動噪音控制技術（Active Noise Control, ANC）。我們利用數位訊號處理器（Digital Signal Processor, DSP）作為技術基礎，並在風扇周圍配置了多個喇叭和麥克風。透過有限脈衝響應（Finite Impulse Response, FIR）濾波器的單通道和多通道回饋（Feedback, FB）以及窄頻前饋（Narrowband Feedforward, NFF）主動噪音控制演算法，成功達到了噪音消除的效果。 本研究會以TMS320C6713 DSK數位訊號處理器開發板搭配類比數位轉換器DSK6713IF-B與DSK_AUDIO4進行ANC實驗，實驗目的包括: 麥克風有無保護之系統效能探討、探討轉速變化之下自適應(Adaptive)以及固定(Fixed)演算法之效能、展示單通道及多通道之ANC系統效能、實現NFF演算法結合轉速信號 (Tachometer, Tach)以實現消除風扇噪音之基頻與其二倍頻、探討加入轉速變化測試NFF + Tach系統能否即時消除改變後的噪音、並且將ANC技術應用於電腦主機上，最後將探討軸流式風扇之寬頻噪音的消除方法。
並列摘要
This thesis focuses on eliminating noise generated by computer axial fans using Active Noise Control (ANC) technology. We employed a Digital Signal Processor (DSP) as the core technology and installed multiple speakers and microphones around the fan. By applying single-channel and multi-channel Feedback (FB) and Narrowband Feedforward (NFF) ANC algorithms with Finite Impulse Response (FIR) filters, we successfully achieved noise reduction. This research utilizes the TMS320C6713 DSK digital signal processor development board, along with the analog-to-digital converters DSK6713IF-B and DSK_AUDIO4, to conduct ANC experiments. The objectives of these experiments include investigating the system performance with and without microphone protection, exploring the effectiveness of adaptive (Adaptive) and fixed (Fixed) algorithms under varying rotational speeds, demonstrating the performance of single-channel and multi-channel ANC systems, implementing the NFF algorithm combined with the tachometer signal (Tach) to eliminate the fundamental and second harmonic frequencies of fan noise, examining the real-time noise cancellation capability of the NFF + Tach system under varying rotational speeds, and applying ANC technology to a computer chassis. Finally, methods for eliminating broadband noise from axial fans will be explored.
參考文獻
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