【摘要】：寬帶波束形成是麥克風陣列信號處理的關鍵技術之一,在音頻信號采集和聲源定位等領域具有廣泛的應用�；跒V波求和結構的空間響應變化約束最小二乘法是近年來新發(fā)展的頻率不變寬帶波束形成器(Frequency invariant beamformer)設計方法,對高性能寬帶音頻信號采集具有重要意義。而近年來所提出的基于Farrow結構的指向可調寬帶波束形成器可以有效解決聲源運動情況下的波束形成問題。本文以寬帶波束形成器的抽頭稀疏化設計為主線,分別對以上兩類寬帶波束形成器設計進行了比較深入的研究。主要研究工作包括:1.研究了基于濾波求和結構的空間響應變化約束最小二乘頻率不變寬帶波束形成器的抽頭稀疏化設計。研究結果表明,該方法的性能受濾波器抽頭長度的影響。通過增大濾波器的抽頭長度,可以改善波束形成器的性能,但是其代價是波束形成器的實現(xiàn)復雜度亦增大。針對這一問題,本文提出了稀疏化設計方法,有效降低了頻率不變寬帶波束形成器的冗余權值。仿真結果表明,與相同抽頭數(shù)量的非稀疏設計方法相比,基于稀疏化設計方法具有更好的性能。2.研究了基于Farrow結構的指向可調魯棒寬帶波束形成器的稀疏化設計。(1)針對麥克風失配誤差有界的條件下,研究了基于最差性能優(yōu)化的設計方法。該方法雖然已成功應用于基于濾波求和結構的波束形成器魯棒設計,但研究結果表明,由于存在過約束問題,該方法并不適用于基于Farrow結構的指向可調寬帶波束形成器設計。(2)針對麥克風失配誤差的均值和方差的分布范圍已知的條件下,研究了基于最差平均性能優(yōu)化和通帶響應方差約束的魯棒設計方法。研究結果表明,當存在麥克風失配誤差時,該方法具有良好的性能。此外,還分析了基于Farrow結構的指向可調寬帶波束形成器的通帶響應方差的一些特性。(3)研究了基于Farrow結構的指向可調寬帶魯棒波束形成器的稀疏化設計。與經典的濾波求和結構波束形成器相比,基于Farrow結構的波束形成器指向可調的實現(xiàn)是以增加濾波器的個數(shù)為代價的。提出了一種基于Farrow結構的指向可調寬帶魯棒波束形成器的抽頭稀疏化方法,有效剔除了波束形成器的冗余抽頭權值,降低了實現(xiàn)復雜度。仿真結果表明,與相同抽頭個數(shù)的非稀疏波束形成器相比,稀疏化設計有效改善了波束形成器的性能。
[Abstract]:Broadband beamforming is one of the key technologies of microphone array signal processing. It has been widely used in audio signal acquisition and sound source location. Spatial response constrained least square method based on filter summation structure is a new design method of frequency invariant wideband beamformer (Frequency invariant beamformer) which is of great significance for high performance wideband audio signal acquisition. In recent years, the Farrow structure based wideband beamformer can effectively solve the problem of beamforming when the sound source is moving. Based on the thinning design of wideband beamformer, the design of these two kinds of wideband beamformer is studied in detail in this paper. The main research work includes: 1. The thinning design of wideband beamformer with variable spatial response constraints and frequency invariant least-squares based on filter summation structure is studied. The results show that the performance of the method is affected by the filter tap length. By increasing the tap length of the filter, the performance of the beamformer can be improved, but the cost is that the implementation complexity of the beamformer is also increased. To solve this problem, a sparse design method is proposed to effectively reduce the redundant weights of frequency invariant broadband beamformer. The simulation results show that the sparse design method has better performance than the non-sparse design method with the same number of taps. The thinning design of directionally adjustable robust wideband beamformer based on Farrow structure is studied. (1) under the condition that microphone mismatch error is bounded, the design method based on worst-case performance optimization is studied. Although the proposed method has been successfully applied to the robust design of beamformer based on filter summation structure, the results of the study show that there are overconstrained problems. This method is not suitable for the design of directionally adjustable wideband beamformer based on Farrow structure. (2) when the distribution range of mean and variance of microphone mismatch error is known, A robust design method based on the worst average performance optimization and passband response variance constraints is studied. The results show that the method has good performance when microphone mismatch error exists. In addition, some characteristics of passband response variance of directional tunable wideband beamformer based on Farrow structure are analyzed. (3) sparseness design of directional tunable wideband robust beamformer based on Farrow structure is studied. Compared with the classical filter summation beamformer, the implementation of Farrow based beamformer with adjustable direction is at the cost of increasing the number of filters. In this paper, a tap thinning method based on Farrow structure for directional tunable wideband robust beamformer is proposed, which effectively eliminates the redundant tap weights of beamformer and reduces the complexity of implementation. The simulation results show that the sparse design improves the performance of the beamformer effectively compared with the non-sparse beamformer with the same number of taps.
【學位授予單位】：南京航空航天大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN911.7
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本文編號：2253687