Friday, 22 July 2005
A.Farina,
L.Tronchin
21/86
Digital
Signal Processing 4
Limits in the FFT analysis
1.The
frequency resolution is constant, whilst the human hearing exhibit narrow resolution at low
frequency, and coarse resolution at high frequency.
2.The
frequency resolution can only be improved employing longer FFT blocks, which means
“averaging” over long times.
3.The
signal should be perfectly steady and periodic, and having a period length exactly equal to the FFT
block size (N).
4.For
processing all the data with the same weight, it is necessary to employing partially
overlapped FFT blocks with proper windows (Hanning, etc.).