用于语音信号的巴特沃思有源低通滤波器方案设计书.docVIP

摘 要 实际上，语音信号在输出时总是不可避免的受到身边环境噪声干扰，和信号接收时电子装置等也会产生噪声干扰。为了能得到原始的语音信号，则需要通过滤波器对受干扰的语音信号进行噪声滤除。针对于多频干扰的语音信号的噪声滤除进行有源低通滤波器设计,使语音信号频率低于截止频率的能完全通过，大于截止频率的将迅速衰减或抑制为零，从而达到噪声信号的过滤，得到原始的语音信号。 首先论述了语音信号的特点和滤波器的基本原理，分析了低通、高通、带通及带阻滤波器的工作原理，并对无源滤波器和有源滤波器进行分析和比较，从而确定滤波器设计选用有源低通滤波器；然后重点地分析了巴特沃斯、切比雪夫和贝塞尔有源低通滤波器各自的特性和优缺点，同时分析了各阶有源低通滤波器基于巴特沃思响应逼近的传递函数，在此基础上,设计了具有压控电压源型电路结构的五阶巴特沃思有源低通滤波器；接着根据滤波器的性能参数及截止频率,选定电容标称值,根据公式得出相应电容值及电阻值，完成滤波电路设计； 最后用Multisim10.0对设计的有源低通滤波器进行仿真分析和用Matlab7.0软件对仿真结果进行理论分析和验证。仿真和验证结果表明，该有源低通滤波器在噪声过滤具有良好的效果。 关键词: 语音信号； 滤波器； 巴特沃思有源低通滤波器； 传递函数 ABSTRACT In fact, the speech signal output is always unavoidable environmental noise interference by side, and when receiving signal, electronic devices also can produce noise interference. In order to get the original speech signal, you need to filter the speech signal of interference with a filter. For multi-frequency interference in the speech signal noise filtering for active low-pass filter design, the speech signal at frequencies below the cutoff frequency can be fully adopted，and greater than the cutoff frequency will decay or inhibit rapidly to zero, so as to achieve noise signal filtering, getting the original speech signal. Firstly, it discusses the characteristics of speech signal and the basic principles of filter, analyzes working principle of the low pass, high pass, band pass and band stop filter, and the passive filters and active filters are analyzed and compared to determine to use active low-pass filter in the filter design. Then it analyzes the focus of Butterworth, Chebyshev, and Bessel active low-pass filter characteristics and advantages and disadvantages of each, and analyzes the transfer function of the order active low-pass filter based on Butterworth response approximation. On this basis, you design a circuit with a voltage-controlled voltage source type of the structure of fifth-order Butterworth active low-pass filter. Then according to the filter performance parameters and cut-off frequency, sele