基于双通道相位差的空域滤波器

Spatial filter Based on Dual Microphone Phase Difference

本文以建立一个基于双通道拾音系统的小尺度、微间距、通带平稳、过渡带陡峭的空域滤波器模型为目标,利用空间中声波的声学传播特性,分析并导出两路信号的相位差与衰减系数之间的关系式。通过对阶梯型衰减系数计算公式优缺点的分析,本文给出了另一种指数型计算公式,在保证通带平稳、过渡带陡峭的性能的同时,能减少阶梯型计算公式带来的语音中断、不连续的现象。同时,本文还提出了一种针对指数型衰减系数空域滤波器主瓣宽度的控制方法,可以精准的控制主瓣宽度,用以适应不同目的的实际使用环境。

In this paper, to establish a mathematical model of a spatial filter with smooth pass band and steep transition zone with vanishingly small separations and small-scale based on dual microphone system, the relationship between the phase difference of the two signals and attenuation coefficient is analyzed and derived using acoustic propagation characteris- tics of sound waves in space. Considering the advantages and disadvantages of step-type attenuation coefficient formula, an- other expression of attenuation coefficient with exponential type is provided, which reduce the voice interruption by using step-type formula, with smooth pass band and steep transition zone at the same time. A method to control the width of the main lobe of the spatial filter using the exponential type expression is proposed, which will adapt to various environments with different purpose.