DSP 平面喇叭視聽系統

Abstract

本篇論文之主要目的是要應用陣列訊號處理之技術來使陣列平面喇叭能夠全向性的傳播聲音. 因此便提出一些方法來設計陣列係數來產生所需要的波束形狀. 並且利用最佳化的方法使全向性的波束在所要的波束平坦度下有最佳的效率. 由於波束的平坦度和效率是複雜且非線性的函數, 因此便使用一種叫基因演算法的方法來做最佳化. 主要是因為這種演算法特別適合對非線性且多函數的問題做最佳化. 另外, 在低頻下可以對全向性的波束做額外的增加效率. 因此便設計令一種波束形狀以避免一些效率的浪費, 如此便可以提高陣列平面喇叭在低頻時候的響應., 而此時波束仍然是全向性的. 在硬體實作中一共架設了一個5×1的喇叭陣列和一個3×3的喇叭陣列用來驗證最佳化的結果. 為了量測聲壓我們也架構了一套自動化量測系統.

Applying the technology of the array signal processing to make the sound radiate omnidirectionally is the main purpose of this paper. Hence the method of designing array coefficients to form omnidirectional pattern was employed in this paper. Further, the efficiency of omnidirectional response was greatly improved by using the method of optimization. The optimization is to find out a set of array coefficients, which has optimal efficiency at desired flatness of sound pattern. Owing to the nonlinear relation between array coefficients and spectral flatness function, a method of optimization called genetic algorithm was employed because of its effective searching global maximum value in nonlinear space. Further, a special case called modified optimal omnidirectional case occurs in low frequency. To provide more efficiency at low frequency is the main purpose in this case.ays.