Units powspctrm

[a.stolk@fcdonders.ru.nl]

Hello Martin,

A powerspectrum typically has the frequencies on one axis and the power of the corresponding frequencies on the other. The power represents how strong a certain frequency occurs in a signal, given by the square of the voltage per frequency.

In your case: square of the microvolts per frequency: uV^2/ Hz

Best regards,
Arjen

----- Original Message -----
From: "Martin Bleichner" <bleichner.martin at GMAIL.COM>
To: FIELDTRIP at NIC.SURFNET.NL
Sent: Thursday, August 12, 2010 5:52:19 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
Subject: [FIELDTRIP] Units powspctrm

Hello together,

What units does the powspctrm have?
Starting with an EEG signal in microvolts and computing the powerspectrum
using freqanalysis what are the units of powspctrm?
I tried to figure it out on my own but I am stuck somehow.

Here some example code

cfg=[];
cfg.method='mtmfft';
cfg.output='pow';
cfg.pad ='maxperlen'
cfg.foilim=[1 130]
cfg.taper='hanning'
cfg.channel=1
cfg.keeptrials='no'

R=ft_freqanalysis(cfg,data);

I am interested in the units of R.powspctrm

Thanks
Martin

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The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.