圆形差分麦克风阵列的二阶波束形成器设计

Second-order Beamformer Design of Circular Differential Microphone Array

针对二阶差分阵(DMA)在信号频率较低时白噪增益异常问题,提出一种基于二阶圆形差分阵列进行白噪增益最大化的波束形成器设计方法。该波束形成器主要是由L阶差分阵列的一阶输出的权值函数h′DMA和WNG情况下的二阶输出的权值函数h′MWNG构成。第一阶段滤波器确定期望波束图的角度,从而在DMA阵列的波束方向上加入空值;第二阶段滤波器解决第一阶段因为白噪异常而导致的系统冗余,从而导致阵列在低频时白噪异常的问题,以解决DMA在低频时WNG异常的问题。仿真结果表明,在相同的条件下,该方法不仅解决了白噪增益异常的问题而且得到的波束图具有更低的旁瓣级。

Aiming at the problem of abnormal white noise gain when the signal frequency is low after the second-order response of the beamformer of differential array(DMA),the design of the maximum white noise gain beamformer is studied,and a white noise based on second-order differential circular array is proposed.The design method of maximizing is gained.The model of differential microphone is analyzed,and the multi-stage cascaded filter model is equivalent to a linear model.The reason of the white noise gain of the differential array is obtained by analyzing the linear model.Then a stepwise solution based on the maximum white noise gain is proposed.Different from the traditional method of solving second-order filter coefficients,this paper splits the second-order filter into two parts to solve the filter coefficients,thus solving the white noise anomaly caused by the low frequency of the array.The simulation results show that under the same conditions,the proposed method not only solves the problem of white noise gain anomaly but also has a lower sidelobe level.