If someone knows the answer, please tell me, thanks again.
psd vs pwelch in matlab
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hi there,
I have a problem,
I compare the result of psd and pwelch, but they showed the different result, why this happened? My matlab version is R2009, unfortunately the matlab delete the description of psd, so would someone tell me why the result of psd and pwelch differs even use the same window? here is my code: ----------------
clear;
Fs=1000;
n=0:1/Fs:1;
y=cos(2*pi*40*n)+3*cos(2*pi*100*n)+randn(size(n));
Nfft=1000;
window=hanning(100);
noverlap=20;
dflag='none';
[Pxx,f]=psd(y,Nfft,Fs,window,noverlap);
figure
plot(f,10*log10(Pxx));
xlabel('frequency/Hz');ylabel('PSD/dB');
title('PSD-Welch method')
hold on;
[Pxx1,f1]=pwelch(y,window,noverlap,Nfft,Fs);
plot(f1,10*log10(Pxx1),'r');
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Answers (2)
Honglei Chen
on 27 May 2015
You should use pwelch. In R2009b, psd is deprecated because the resulting power spectral density is not properly normalized. The shape is correct though.
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