example6_15.m

数字信号处理的比较全面的程序代码

% Digital Filter Specifications:
wp=0.2*pi;               %         digital Passband freq in rad
ws=0.3*pi;               %         digital Stopband freq in rad
Rp=1;                    %         Passband ripple in dB
As=15;                   %         Stolband attenuation in dB
% Analog Prototype Specifications:Inverse mapping for frequencies
T=1;Fs=1/T;              %    Set T=1
OmegaP=(2/T)*tan(wp/2);  %    Prewarp Prototype Passband freq
OmegaS=(2/T)*tan(ws/2);  %    Prewarp Prototype Stopband freq
% Analog Chebyshev-1 Prototype Filter Calculation:
[cs,ds]=afd_chb1(OmegaP,OmegaS,Rp,As);
% ***Chebyshev-1 Filter Order=4
% Bilinear transformation:
[b,a]=bilinear(cs,ds,Fs);
[C,B,A]=dir2cas(b,a);
[db,mag,pha,grd,w]=freqz_m(b,a);