% Routine 3.2b     Bode plot of H = 1 + z^-6
clear all;
fS= 720;
T = 1/fS;
f = 0:fS/2;
o = 2*pi*f;
w = exp(-i*o*T);
H = 1 + w.^6;
r = abs(H);
phi = angle(H);
plot(f,360*phi/(2*pi),'k-')
%plot(f,r)