IIR 数字滤波器的设计与实现

代码说明：

  设计一个巴特沃兹数字低通滤波器，其技术指标为：3dB带宽为0.2π，阻带截止频率为0.3π，通带纹波为1dB，阻带衰减大于30dB，采样间隔T=10ms。 1）采用冲激响应不变法； 2）采用双线性变换法设计； 3）采用FIR的窗函数（Hanning窗、Hamming窗或Blackman窗）设计。(A Butterworth digital low-pass filter is designed. Its technical specifications are: 3 dB bandwidth is 0.2 pi, stopband cut-off frequency is 0.3 pi, passband ripple is 1 dB, stopband attenuation is more than 30 dB, sampling interval T=10 Ms. 1) Impulse response invariance method is adopted. 2) Design by bilinear transformation method; 3) FIR window function (Hanning window, Hamming window or Blackman window) is used to design.)