Phase-plot when using freqz

63 visualizaciones (últimos 30 días)
Alex
Alex el 25 de Mzo. de 2011
Hi all.
Why does these two methods not create the same plot?
figure()
G3=[0.0178750173569734]
num3=[1,-2.22044604925031e-16,-1.00000000000000]
den3=[1,-1.96419015432470,0.964249965286053]
freqz(G3*num3,den3,1000,44100);
ax = findall(gcf, 'Type', 'axes');
set(ax, 'XLim', [0 500]), ylim([-15 1])
Amplitude-plot is the same, but phae plot differ from this one:
[H,w]=freqz(G3*num3,den3,1000,44100);
figure(), subplot(2,1,1)
plot(w,20*log10(abs(H)))
title('Frekvenskarakteristik')
xlabel('Frekvens [Hz]'), ylabel('Amplitude [dB]')
axis([0 500 -15 1]), grid
subplot(2,1,2)
plot(w,angle(H))
xlabel('Frekvens [Hz]'), ylabel('Fase')
axis([0 500 -100 50]), grid

Respuesta aceptada

Vieniava
Vieniava el 25 de Mzo. de 2011
It is a matter of expressing angle in degrees or radians. Replace:
plot(w,angle(H))
with
plot(w, 360/(2*pi)*angle(H))

Más respuestas (1)

Hassan Naseri
Hassan Naseri el 1 de Abr. de 2011
You still need to unwrap the result to be the same as freqz output:
unwrap(angle(h)
or if you want it in degrees:
360/(2*pi)*unwrap(angle(H))
  1 comentario
gbernardi
gbernardi el 8 de Nov. de 2012
This topic could be dead now, but I'd still like to point out that in some cases I cannot obtain the same result of freqz, although I perform both rad2deg conversion and phase unwrapping...
Has anybody experience this problem?

Iniciar sesión para comentar.

Etiquetas

Productos

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by