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Topic: Spectrogram: nfft vs. window. How's that??
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Posts: 77
Registered: 6/6/12
Spectrogram: nfft vs. window. How's that??
Posted: Mar 15, 2013 9:34 AM
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I admit from the beginning that I do not have so much knowledge about stft and the topic.
But anyway I need a "quick and dirty" spectrogram of a signal, and there's something I do not get.
The parameters are :
spectrogram (x,window,noverlap,nfft,.....);
What's the difference between window and nfft and how (therefore) am I supposed to set these two parameter? It seems pretty obvious to me that they are dependent.
Arent't they?

I quote from the doc:
"window is a Hamming window of length nfft."
"nfft is the FFT length and is the maximum of 256 or the next power of 2 greater than the length of each segment of x. Instead of nfft, you can specify a vector of frequencies, F. See below for more information."

Why should I specify "window" then?
And would it make sens to set it to anything different from fft?

Can anybody shed some light on it?
And BTW... does anybody has a rule of thum on how to set these parameters in a "kinda optimal way" (depending on what I want to analyze)

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