How to see a part of my FFT plot in magnified size in other window?
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I have drawn a FFT plot for my data and now I want to show a particular part of my plot in zoom. How to do it , Please guide me?
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Wayne King
le 8 Jan 2014
You can simply use
>>zoom on
Or you can set your xlim and/or ylim properties appropriately:
Fs = 1000;
t = 0:1/Fs:1;
x = cos(2*pi*100*t)+randn(size(t));
xdft = fft(x);
plot(abs(xdft))
% now do the following
set(gca,'xlim',[0 200])
You can do the same for the 'ylim' as well if you like.
Or finally, you can just plot the relative portion of the output of fft() to begin with:
plot(abs(xdft(1:201)))
Wayne King
le 8 Jan 2014
You can do something like that with subplot
Fs = 1000;
t = 0:1/Fs:1-1/Fs;
x = cos(2*pi*100*t)+randn(size(t));
xdft = fft(x);
xdft = xdft(1:length(x)/2+1);
df = Fs/length(x);
freqvec = 0:df:Fs/2;
subplot(211)
plot(freqvec,abs(xdft)); xlabel('Hz');
subplot(212)
plot(freqvec(1:201),abs(xdft(1:201)));
xlabel('Hz');
Why do you need to have that callout graphic like you show in your document. You can do that, but it is much more complicated and what purpose does it serve?
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