FFT peak estimation - binning
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Hi,
I want to determine a tendency of the dominant peak in the frequency domain of a dataset. I use 6 seconds of data and sample it at 20Hz. I calculate the FFT and I can determine the dominant peak. But now I want to get a better view and I want to bin the FFT function and determine the value of the biggest peak. I want bins with a size of 0.1Hz. Does anybody knows how to do it, because the method I'm using now takes sometimes 2 values from the original FFT for 1 bin and sometimes just 1 value from the original FFT for a bin and this gives a very bad result.
Thank you in advance,
Peter
回答（1 个）
bym
2011-5-16
0 个投票
Unless I am missing something, you need a longer sample than 6 seconds. Frequency resolution = FFT points/fs
In your case 120/20 = .1667 To get .1 Hz resolution you would need 200 points or 10 seconds of data
3 个评论
Walter Roberson
2011-5-16
Thud! Guess I wasn't quite awake yet when I did my calculation :(
bym
2011-5-17
Never thought I'd get the drop on the rascally raccoon!
Walter Roberson
2011-5-17
Or to put it a different way, for any fixed sampling frequency, provided the Nyquist criteria is met, frequency resolution = 1/T, so to get 0.1 Hz resolution, you would need 1/0.1 Hz = 10 seconds of data.
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