Problems with frequency analysis...

[Carina Graversen]

Hi.

I have a problem regarding the function "freqanalysis", that I hope
some of you can help me with.

I have a Neuroscan .avg file called testdata.avg, and I would like to
see a time-frequency plot of all the 64 channels.
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In order to do this, I try the following:

cfg1                                    = [];
cfg1.datafile                           = 'testdata.avg'
cfg1.headerfile                         = 'testdata.avg'
dataFIC                                 = preprocessing(cfg1);

This gives me the data in dataFIC, and if I look at the data in
dataFIC.trial{1} I get the correct data for all the 64 channels, so no
problem here :o).
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The next I try is:

cfg2                                    = [];
cfg2.output                             = 'pow';
cfg2.channel                            = 'all';
cfg2.method                             = 'mtmconvol';
cfg2.taper                              = 'hanning';
cfg2.foi                                = 2:2:30;
cfg2.t_ftimwin                          = ones(length(cfg2.foi),1).*0.5;
cfg2.toi                                = 0.050:0.005:0.500;

TFRhann                                 = freqanalysis(cfg2, dataFIC);

I would have expected to get the time-frequency coefficients in the
TFRhann.powspctrm, but all I get is a lot of NaNs :o(.

Am I doing something wrong, and should I set more parameters for the cfg2 ???
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When the problem with the freqanalysis is solved, I expect to be able
to make the plots this way - does it look right (the testlay_64.lay
file is one I have generated myself, and if I just run the code with
the TFRhann with all the NaNs, at least the electrodes appear at the
right location in the plot.

cfg3.zparam     = 'powspctrm';
cfg3.xlim       = [0 0.5];
cfg3.ylim       = [1 29];
cfg3.zlim       = [-3e-27 3e-27];
cfg3.layout     = 'testlay_64.lay';
cfg3.showlabels = 'yes';

multiplotTFR(cfg3, TFRhann)
___

I look forward to all suggestions regarding the problems with "freqanalysis".

Best regards,
Carina Graversen
Ph.D student at Aalborg Hospital, Denmark

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