[FieldTrip] Non-integer Frequencies in ft_freqanalysis

MUSTAFA YAVUZ m.yavuz.18 at ogr.iu.edu.tr
Wed Oct 21 00:43:08 CEST 2020


Dear Todd Calnan,

As I know, the output for the mtmfft method depends on the length of the
time window of your interest. To calculate your output frequencies, you may
check this link:
https://www.fieldtriptoolbox.org/faq/why_does_my_output.freq_not_match_my_cfg.foi_when_using_mtmfft_in_ft_freqanalyis/


However, you may also consider to apply other ft_freqanalysis methods( e.g.
wavelets or hannings) to obtain power for non-integer frequency values.

Hope it helps,
Best wishes,
Mustafa

Todd Calnan <tcalnan2 at gmail.com>, 20 Eki 2020 Sal, 23:31 tarihinde şunu
yazdı:

> Dear FieldTrippers,
>
> I am working on calculating EEG frequency band ratios (ie beta-gamma
> ratio) using the results of ft_freqanalysis on my dataset. However, I am
> trying to include non-integer frequencies so that there is no overlap
> between the bands, so that beta will go from 13.0 to 29.9 Hz and gamma will
> go from 30.0 to 54.9 Hz. When I try to set this up in the cfg variable for
> ft_freqanalysis (attempting to do the inverse of the fieldtrip spectral
> analysis tutorial), using
>
>     cfg.method = 'mtmfft';
>     cfg.pad    = 'maxperlen';
>     cfg.taper  = 'hanning';
>     cfg.foi = 1:0.1:100;    % go from 1 Hz to 100 Hz in 0.1 Hz intervals
>     cfg.trials = 'all';
>     cfg.output = 'powandcsd';
>     cfg.keeptrials = 'yes';
>     cfg.channel = (1:39)';
>
> I still only end up with the 100 frequencies, rather than the 1000 that I
> was hoping for.
>
> Is it possible to break up the frequencies in ft_freqanalysis by more than
> 1 Hz bins to allow for more discrete analysis?
>
> Thank you for any help.
>
> -Todd Calnan
>
> *Todd M. Calnan*
> Database Analyst
> Duke Center for Autism and Brain Development
> Duke University School of Medicine
> todd.calnan at dm.duke.edu
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> https://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> https://doi.org/10.1371/journal.pcbi.1002202
>
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