AW: [FIELDTRIP] complex wavelet output

[Brian Roach]

Hi Juergen,

You can also use cfg.method = 'wltconvol', but you need to change a line
of code in the freqanalysis_wltconvol.m script.  When you use
cfg.keeptrials = 'yes', it will normally return single trial power data
(not complex numbers), but in the script search for:

elseif keep == 2
            powdum = XYZ ;

make sure that XYZ does not have any squaring or abs calls around it.
These change complex numbers to real ones.

Brian
Hanneke Van Dijk wrote:
> Dear Juergen,
>
> As far as I can see, you can specify cfg.output = 'fourier' for the cfg.method = 'mtmconvol' when you want to have a time axis as well (it's also possible for 'mtmfft'). It will give you the fourierspectrum. You can set the parameters of mtmconvol such that it operates simmilar to a wavelet transform as you can see on this website:
>
> http://fieldtrip.fcdonders.nl/tutorial/timefrequencyanalysis
>
> An example of the parameters could be:
>
> cfg = [];
> cfg.output     = 'fourier';
> cfg.channel    = 'MEG';
> cfg.method     = 'mtmconvol';
> cfg.taper      = 'dpss';        % sleppian taper but you can use different tapers/windows here.
> cfg.foi        = 1:2:30;        % frequencies of interest.
> cfg.t_ftimwin  = 5./cfg.foi;    % the window length is 5 cycles of the specified frequency long.
> cfg.tapsmofrq  = 0.4 *cfg.foi;  % frequency smoothing of +/- 0.4*the specified frequency.
> cfg.toi        = -0.5:0.05:1.5; % time of interest.
> cfg.pad        = 'maxperlen';
> TFRmult = freqanalysis(cfg, dataFIC);
>
> Hope it helps!
>
> Yours,
>
> Hanneke
>
>
> -----Ursprüngliche Nachricht-----
> Von: FieldTrip discussion list im Auftrag von Juergen Fell
> Gesendet: Mi 07.10.2009 10:14
> An: FIELDTRIP at NIC.SURFNET.NL
> Betreff: [FIELDTRIP] complex wavelet output
>
>
>
> Dear fieldtrip users:
>
> I've just started digging into fieldtrip and came across the following
> question: is it possible to obtain the complex output of the continuous
> wavelet transform, i.e. the original wavelet-transformed complex signal
> (instead of power and/or cross-spectral density)?
>
> Any help would be greatly appreciated.
>
> Juergen.
>
> ----------------------------------
> 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.
>
>

----------------------------------
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.