Power Units in Freqanalysis

Paco Diaz pacodiaz at UB.EDU
Wed Nov 12 15:59:47 CET 2008


Hi all,

  I have performed a time frequency analysis on the evoked activity for EEG
data whose units where (of course) in microVolts. It seems that it all work
fine, but I would appreciate some help to understand my results (my plot
actually). Below you can see the configuration structure that I have used.
Well, the question is as follows, which are the units for the z-axis (color
code)??

  I think that they should be (microV)^2 but the values I'm obtainning are
very low when  compared with the literature, my maximum value is 8*10^-3 but
i have found in the literature values between 8 and 70 (microV)^2. Is there
a scale factor that I am missing or is it all simply wrong??

cfg=[];
cfg.method='tfr';
cfg.output='pow';
cfg.foi=[30:0.5:40];
cfg.width=7;
cfg.gwidth=5;

tfr_data=freqanalysis(cfg,data);

  Thank you,
  Paco.

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