[FieldTrip] Wavelet- Time frequency analysis

Schoffelen, J.M. (Jan Mathijs) jan.schoffelen at donders.ru.nl
Fri Aug 12 18:32:42 CEST 2016


If your sampling rate is 30K, then your time axis should be something like (1:size(data.trial{1},1))./data.fsample; rather than 1:some-number


On 12 Aug 2016, at 18:09, Bahareh Elahian (belahian) <belahian at memphis.edu<mailto:belahian at memphis.edu>> wrote:


Thanks for suggestions.
The data.fsample is 30K.

I want to see HFOs in time- frequency plot.
Wavelet is one solution of that.
The error which I am getting is coming from padding and I do not know where should I fix it.
What should I do if I do not want any padding?

Bahar

On Aug 12, 2016, at 11:04 AM, Schoffelen, J.M. (Jan Mathijs) <jan.schoffelen at donders.ru.nl<mailto:jan.schoffelen at donders.ru.nl>> wrote:

It is correct as far as the data.fsample is consistent with this (which I suspect it isn’t).

If you are interested in HFO, why not bandpassfilter your data and do a Hilbert transform?

Best,
Jan-Mathijs


On 12 Aug 2016, at 17:15, Bahareh Elahian (belahian) <belahian at memphis.edu<mailto:belahian at memphis.edu>> wrote:

Thanks for the answer,
They are the same actually my cfg.toi is my data.time.
I specified them the same as each other . was it right?
________________________________
From: fieldtrip-bounces at science.ru.nl<mailto:fieldtrip-bounces at science.ru.nl> <fieldtrip-bounces at science.ru.nl<mailto:fieldtrip-bounces at science.ru.nl>> on behalf of Schoffelen, J.M. (Jan Mathijs) <jan.schoffelen at donders.ru.nl<mailto:jan.schoffelen at donders.ru.nl>>
Sent: Friday, August 12, 2016 10:08:20 AM
To: FieldTrip discussion list
Subject: Re: [FieldTrip] Wavelet- Time frequency analysis

Note that the units of the time points specified in cfg.toi should coincide with the units in the time axis of the data, i.e. data.time.

JM


On 12 Aug 2016, at 16:51, Bahareh Elahian (belahian) <belahian at memphis.edu<mailto:belahian at memphis.edu>> wrote:


Hi All,

I am trying to apply wavelet on my signal to see HFOs.
According to http://www.fieldtriptoolbox.org/tutorial/timefrequencyanalysis
I wrote the following lines but I will get an error that: "the padding that you specified is shorter than the data".
As far as I understood 'maxperlen' is the default.
Any other idea for padding or solving this problem?
[https://www.bing.com/th?id=OVP.V249f2fff057aa7a9c87ce8b67ec6c972&pid=Api]<http://www.fieldtriptoolbox.org/tutorial/timefrequencyanalysis>

tutorial:timefrequencyanalysis – FieldTrip<http://www.fieldtriptoolbox.org/tutorial/timefrequencyanalysis>
www.fieldtriptoolbox.org<http://www.fieldtriptoolbox.org/>



cfg= [];
cfg.pad = 'maxperlen';
cfg.method = 'wavelet';
cfg.output = 'pow';
cfg.channel = 'chan 4';
cfg.toi = 1:size(eeg.eeg_data,2);
cfg.foilim  = [80 500];
[freq] = ft_freqanalysis(cfg, data1);



data1 is  my data which I get by applying ft_preprocessing.
_________________________________________________
Bahar
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