IIR, Chebyshev-II, butterworth highpass

cheb2

close all; clear all; clc;

%% 1. specs

fm = 64e3;

wp = 20e3*2*pi;

ws = 16e3*2*pi;

Ap = 1;

As = 40;

%% 2. prewarp

wap = 2*fm*tan(wp/(2*fm));

was = 2*fm*tan(ws/(2*fm));

%% 3. convert to low pass

wlpp = 1/wap;

wlps = 1/was;

%% analog prototype cheb2

e2 = 1/(10^(0.1*As)-1);

n = acosh( sqrt((10^(0.1*Ap)-1)/e2) ) / acosh(wlps/wlpp);

n = ceil(n);

wc = 1/wlpp;

[z,p,k] = cheb2ap(n,As);

[Bn,An] = zp2tf(z,p,k);

[B,A] = lp2hp(Bn,An,wc);

[Bz, Az] = bilinear(B,A,fm);

figure; freqz(Bz,Az,5000,fm);

figure; grpdelay(Bz,Az,5000,fm);

figure; impz(Bz,Az,50);

butterworth