以數位訊號處理器為基礎之即時麥克風陣列系統之研製與評估

Abstract

近年來在 AV 市場中，以麥克風陣列擷取聲音訊號的方式受到相當 大的重視。 由於麥克風陣列具有電子指向以及干擾消除等優異的特性， 使得其十分適合於接收 移動音源。 在本論文中，吾人以多通道的數位 訊號處理器架構了一個即時麥克風 陣列系統。 藉著一分區多重波束功 率比較的演算法，此系統能夠擷取並追蹤聲音 訊號。 當環境中存在強 大干擾訊號時，麥克風陣列則切換到適應性模式，利用一 改良的 Frost 型寬頻波束合成器，以壓抑非目標訊號的部份。經由 數值模擬以及實際 資料的實驗，吾人證實了此一陣列系統確實呈現了目標訊號增強 以及干 擾訊號壓抑的能力。 若能更進一步提高麥克風的品質，以及增加數位訊 號處理器 的運算能力，則麥克風陣列系統將可適用於更複雜的環境。 The use of microphone arrays for the acquisition of sound signals hasreceived considerable attention in recent AV markets. A microphone array hasthe distinctive features of electronic beam steering and interferencesuppression which make it suitable for mobile sound source pickup. In thisthesis, a real-time microphone array system operating with a multi-channelDSP board is presented. The system acquires and keeps track of sound signalsvia a sectorized multi-beam power comparison algorithm. In case that stronginterference exists, the array can switch to an adaptive mode in which amodified Frost type broadband beamformer is employed to weaken the unwantedsignal components. Through a set of numerical simulations and real dataexperiments, we demonstrate that the developed array system does indeedexhibit the desired signal enhancement and interference suppressioncapabilities. Further efforts could be directed toward improving themicrophone element quality and increasing the numerical power of the DSPboard.