cheb1hpf.m

来自「the file contain many matlab signal sour」· M 代码 · 共 26 行

function [b,a]=cheb1hpf(wp,ws,Rp,As);
% IIR Highpass filter design using Chebyshev-1 prototype
% [b,a]=cheb1hpf(wp,ws,Rp,As)
% b=Numerator polynomial of the highpass filter
% a=Denominator polynomial of the highpass filter
% wp=Passband frequency in radians
% ws=Stopband frequency in radians
% Rp=Passband ripple in dB
% As=Stopband attenuation in dB
%
% Determine the digital lowpass cutoff frequencies:
wplp=0.2*pi;
alpha=-(cos((wplp+wp)/2))/(cos((wplp-wp)/2));
wslp=angle(-(exp(-j*ws)+alpha)/(1+alpha*exp(-j*ws)));
%
% Compute Analog lowpass Prototype Specification:
T=1;Fs=1/T;
OmegaP=(2/T)*tan(wplp/2);
OmegaS=(2/T)*tan(wslp/2);
% Design Analog Chebyshev Prototype Lowpass Filter:
[cs,ds]=afd_chb1(OmegaP,OmegaS,Rp,As);
% Perform Bilinear transformation to obtain digital lowpass
[blp,alp]=bilinear(cs,ds,Fs);
% Transform digital lowpass into highpass filter
Nz=-[alpha,1];Dz=[1,alpha];
[b,a]=zmapping(blp,alp,Nz,Dz);