Frequency domain of wvtool - how to replicate?

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I'm trying to obtain the frequency domain (in dB) data of a Kaiser window and I'm unable to duplicate what results from the "wvtool". My code is below. Why does my fft plot not show all the side lobes that are shown in the Frequency Domain of the wvtool GUI?
if true
% code
end
N=100;
w = window(@kaiser,N,1)
figure(1);subplot(1,2,1);
plot(w);
subplot(1,2,2);
plot(db(abs(fft(w))));axis([0 50 -80 40]);
wvtool(w)

Accepted Answer

Honglei Chen
Honglei Chen on 12 Aug 2016
You need more points in there. The default is probably 512 or 1024. Try
plot(db(abs(fft(w,1024))));axis([0 50 -80 40]);
HTH
  1 Comment
Andy
Andy on 15 Aug 2016
Edited: Andy on 15 Aug 2016
Thank you. And just to add a detail - I need to change the "axis" properties to see all the extra lobes:
if true
% code
end
plot(db(abs(fft(w,1024))));axis([0 512 -80 40]);

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