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Filtering noisy data

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vsee
vsee on 17 Apr 2011
Hello
I have a mixed frequency signal with a lot of noise. I plotted the spectrum of the signal using fft and also plotted the psd of the signal using the sp tool. I don't quite see the peak of the signal in fft plot althought the psd plot shows a peak and then rolls off. I don't know if i am missing to interpret something in the fft plot? I can attach the plots but don't know how. Thanks.
  3 Comments
vsee
vsee on 18 Apr 2011
Here is the link to the plot.
http://www.yorkphoto.com/york/slideshow/AlbumID=3615814002/PictureID=206725940002/a=100160453_100160453/
Thanks

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Answers (1)

Walter Roberson
Walter Roberson on 18 Apr 2011
What was plotted for the fft? Real, Imaginary, Magnitude ?
  1 Comment
vsee
vsee on 18 Apr 2011
It was the magnitude(log). Here is my code.
hresignal = csvread('2RH8June.csv');
time = hresignal(:, 1);
amp = hresignal(:, 2);
samp = hresignal(1:1000000, 2);
fsamp = 20*log10(abs(fft(samp)));
ps = psd(spectrum.welch,samp);
subplot(2,1,1),plot(fsamp);
subplot(2,1,2),plot(ps);

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