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faq:why_does_my_tfr_look_strange_part_ii [2013/01/08 01:47]
ingrid [Why does my TFR look strange (part II, detrending)?]
faq:why_does_my_tfr_look_strange_part_ii [2017/08/17 11:21] (current)
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 {{:​faq:​strangetfr3.png?​400|}}\\ {{:​faq:​strangetfr3.png?​400|}}\\
 This phenomenon is caused by the time domain data having a slow low-frequency drift. This low-frequency component leaks into the estimates of all time-frequency points in a variable (but patterned) way. The reason why this actually happens is related to the fact that none of the tapered basis functions (i.e. windowed sine and cosine waves of increasing frequency) are exactly orthogonal to this slow drift. This phenomenon is caused by the time domain data having a slow low-frequency drift. This low-frequency component leaks into the estimates of all time-frequency points in a variable (but patterned) way. The reason why this actually happens is related to the fact that none of the tapered basis functions (i.e. windowed sine and cosine waves of increasing frequency) are exactly orthogonal to this slow drift.
-The solution to this problem is to detrend or high-pass filter ​your data your data prior to calling ft_freqanalysis:​+The solution to this problem is to detrend or high-pass filter your data prior to calling ft_freqanalysis:​
  
 <​code>​cfg = []; <​code>​cfg = [];