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difx:difx-sfxc_comparison

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difx:difx-sfxc_comparison [2015/11/19 14:35]
adamdeller
difx:difx-sfxc_comparison [2015/11/20 15:44]
adamdeller
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 This shows the result of a zero-padded FFT, no windowing. ​ The peak is the same height, but the noise is marginally reduced. This shows the result of a zero-padded FFT, no windowing. ​ The peak is the same height, but the noise is marginally reduced.
  
-{{:​difx:​verification:​zeropadded.png?500|}}+{{:​difx:​verification:​windowed.png?500|}}
  
 This shows the result of windowed-overlapped FFT (Hamming window), no zero padding. ​ The peak goes up but it is sitting on a plateau of higher noise. ​ If you just estimate the noise globally, then the S/N seems higher, but if you use an estimate of the local noise in the vicinity of the peak, the S/N is the same. This shows the result of windowed-overlapped FFT (Hamming window), no zero padding. ​ The peak goes up but it is sitting on a plateau of higher noise. ​ If you just estimate the noise globally, then the S/N seems higher, but if you use an estimate of the local noise in the vicinity of the peak, the S/N is the same.
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 | Hanning window + overlap, zero padded, averaged 4x in freq | 17.37 | 15.94           | | Hanning window + overlap, zero padded, averaged 4x in freq | 17.37 | 15.94           |
  
-So as you can see, the S/N estimated locally is always pretty comparable, even though the S/N estimated globally is 35% higher with a windowed overlap.+So as you can see, the S/N estimated locally is always pretty comparable, even though the S/N estimated globally is 35% higher with a windowed overlap.  Zero padding does help a little, but at the level of 2-3%.
  
difx/difx-sfxc_comparison.txt · Last modified: 2015/11/20 15:44 by adamdeller