[FieldTrip] Question pertaining to frequency resolution

Wijs, C. c.wijs at student.rug.nl
Tue May 18 14:53:58 CEST 2021

Dear Eelke, and others,

Thank you for your response. Is it then correct that even though my time
window of 500 ms constitutes a 2 Hz frequency, by adding a zero padding of
1 second, I can safely interpret the odd numbered frequencies (as was
discussed in the tutorial I mentioned in my original post/submission)?
Obviously I would report that for the analysis I applied zero-padding,
cause as you say, it is a bit of a trick.

The code I think to use would then be like this:

cfg                   = [];
cfg.output        = 'pow';
cfg.method      = 'mtmconvol';
cfg.taper          = 'hanning';
cfg.keeptrials   = 'yes';
cfg.pad             = 1;
cfg.foi               = 2:1:14;                         % analysis 2 to 14
Hz in steps of 1 Hz
cfg.t_ftimwin    = ones(length(cfg.foi),1).*0.5;   % length of time window
= 0.5 sec
cfg.toi               = -0.1:0.004:0.6;                  % time window
"slides" from -0.1 to 0.6 sec in steps of 0.004, for example, 0.004 as I
have (EEG) sampling frequency of 250hz
TFRdata = ft_freqanalysis(cfg, data_clean);

Or could I even use an even smaller time window, such that I lose less of
my data and have a longer period over which I can analyse the power spectra?

Again thank you and have a nice day,

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