exa4_2.m

matlab应用实例。如：FIR、IIR数字滤波器设计等。

% exa4-2_Chebyshev_I for example4-2
% Chebyshev I analog lowpass filter

clear all;
n=0:0.01:2;
for i=1:4
    switch i
        case 1
            N=2;
        case 2
            N=4;
        case 3 
            N=6;
        case 4
            N=8;
    end
    Rp=1;
    [z,p,k]=cheb1ap(N,Rp);
    [b,a]=zp2tf(z,p,k);
    [H,w]=freqs(b,a,n);
    magH2=(abs(H)).^2;
    % Output figure
    posplot=['22' num2str(i)];
    subplot(posplot)
    plot(w,magH2)
    axis([0 2 0 1]);
    xlabel('w/wc');
    ylabel('|H(jw)|^2');
    title(['N=' num2str(N)]);
    grid on
end