1）设计Butterworth型音频抗混叠滤波器；

2）参数：

下通带频率300Hz；上通带频率3400Hz；

下阻带频率280Hz；上阻带频率3600Hz；

通带最大衰减0.3dB；

阻带最小衰减40dB；

3）采用一低通滤波器和一高通滤波器级联；

4）分别确定LPF和HPF的性能指标；

5）求出两滤波器的系统函数和频率响应，并画出其幅频特性曲线；

6）求整个滤波器的系统函数和频率响应，并画出其幅频特性曲线。-1) the design of Butterworth-type audio anti-aliasing filter　2) parameters: passband frequency of 300Hz　on pass-band frequency 3400Hz　under the stop-band frequency of 280Hz　on stop-band frequency 3600Hz　passband maximum attenuation of 0.3dB　minimum stopband attenuation of 40dB　3) the use of a low-pass filter and a high-pass filter cascade　4) separately to determine the performance of LPF and HPF target　5) to derive two-filter system function and frequency response, and draw its increase frequency characteristic curve　6) for the entire filter system function and frequency response, and draw its amplitude-frequency characteristic curve.