Time Frequency Analysis!

[Christian Hesse]

> A brief on how to do i get the data1, I have the data for 24000  
> data points with 800 Hz sampling rate (30 secs of data), i  
> construct my own data format according to the data format specified  
> in fieltrip with
> data.label,fsample,trial,time.
> I tried the way you have mentioned with the window length
> this is what i do
>
> cfg=[];
> winlen=0.5;
> halfwin=winlen/2;
> nwin=2.*(30./winlen)-1;
> cfg.output='pow';
> cfg.method='mtmconvol';
> cfg.channel    = channelselection({'all' 'all'}, data1.label);
> cfg.foi=2:1:30;
> cfg.t_ftimwin=zeros(1,nwin).*winlen;

this should be
cfg.t_ftimwin=ones(1,nwin).*winlen;

Christian



> cfg.toi=[0:halfwin:30-winlen];
> cfg.taper='hanning';
> cfg.pad=2;
> cfg.keeptrials='no';
> TFRmult=freqanalysis(cfg,data1);
>
> and it throws a error
> ??? Subscript indices must either be real positive integers or  
> logicals.
>
> Error in ==> freqanalysis_mtmconvol at 424
>          autspctrmacttap(sgnlop,:) = dum(acttimboi);
>
> Error in ==> freqanalysis at 167
> [freq] = feval(sprintf('freqanalysis_%s',lower(cfg.method)), cfg,  
> data);
>
> Please let me know, why do i get this error
>
>
> Thanking you
>
> with regards
> M.Muthuraman.
>
>> From: Christian Hesse <c.hesse at FCDONDERS.RU.NL>
>> Reply-To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
>> To: FIELDTRIP at NIC.SURFNET.NL
>> Subject: Re: [FIELDTRIP] Time Frequency Analysis!
>> Date: Mon, 19 Feb 2007 13:12:03 +0100
>>
>> Hi Muthuraman,
>>
>> ok, in that case you can try the following (this assumes you have   
>> windows of length "winlen" which overlap by "halfwin = winlen/2")
>>
>> winlen = 0.5;
>> % this is in seconds you can also use another time window
>> halfwin = winlen/2;
>>
>> % the total number of windows covering the 30 second period
>> nwin = 2.*(30./winlen) - 1;
>>
>> cfg.method = 'mtmconvol';
>> cfg.output = 'pow';
>> cfg.t_ftimwin = ones(1,nwin).*winlen;
>> cfg.toi = [0:halfwin:30-winlen];
>>
>> The important things here to check are
>> 1) that cfg.t_ftimwin and cfg.toi contain the same number of elements
>> 2) the times you specify in cfg.toi actually correspond to your  
>> time  axis (i.e. do not start before or go on after).
>>
>> If you want to use a different overlap, you need to calculate  
>> nwin  slightly differently.
>>
>> Hope this helps more,
>> Christian
>>
>>
>>
>>> Thanks for the suggestion but using the mtmfft which i have done   
>>> already and it works, my interest now is that i would like to  
>>> use  the Time frequency analysis 'mtmconvol'  to estimate the  
>>> power in  the time frequency scale, in which how to get the whole  
>>> 30secs  continous  data in one time frequency plot(TFR).
>>>
>>> Thanking you
>>>
>>> with regards
>>> M.Muthuraman.
>>>
>>>> From: Christian Hesse <c.hesse at FCDONDERS.RU.NL>
>>>> Reply-To: FieldTrip discussion list <FIELDTRIP at NIC.SURFNET.NL>
>>>> To: FIELDTRIP at NIC.SURFNET.NL
>>>> Subject: Re: [FIELDTRIP] Time Frequency Analysis!
>>>> Date: Mon, 19 Feb 2007 11:56:19 +0100
>>>>
>>>> Hi Muthuraman,
>>>>
>>>>> One more question regarding the Time frequency Analysis, i  
>>>>> have  EMG  data of 24000 data points with a sampling frequeny  
>>>>> of 800Hz (30  seconds of continous data). I would like to do  
>>>>> the  Timefrequency  analysis for this data and to see the power  
>>>>> for  the whole 30 seconds
>>>>
>>>> use preprocessing to get the EMG data into a single 30s trial  
>>>> (if  you  want to analyze the rectified EMG, then do the  
>>>> rectification  in  preprocessing), then use frequanalysis with
>>>>
>>>> cfg.method = 'mtmfft';
>>>> cfg.output = 'pow';
>>>>
>>>> this should give you the power spectrum of your EMG data over  
>>>> the   entire 30 second period.
>>>>
>>>> Regards,
>>>> Christian
>>>>
>>>>
>>>> ------------------------------------------------------------------- 
>>>> -- -
>>>> Christian Hesse, PhD, MIEEE
>>>>
>>>> F.C. Donders Centre for Cognitive Neuroimaging
>>>> P.O. Box 9101
>>>> NL-6500 HB Nijmegen
>>>> The Netherlands
>>>>
>>>> Tel.: +31 (0)24 36 68293
>>>> Fax: +31 (0)24 36 10989
>>>>
>>>> Email: c.hesse at fcdonders.ru.nl
>>>> Web: www.fcdonders.ru.nl
>>>> ------------------------------------------------------------------- 
>>>> -- -
>>>>
>>>>
>>>>
>>>>
>>>
>>> _________________________________________________________________
>>> Tried the new MSN Messenger? It’s cool! Download now. http://  
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>>
>> --------------------------------------------------------------------- 
>> -
>> Christian Hesse, PhD, MIEEE
>>
>> F.C. Donders Centre for Cognitive Neuroimaging
>> P.O. Box 9101
>> NL-6500 HB Nijmegen
>> The Netherlands
>>
>> Tel.: +31 (0)24 36 68293
>> Fax: +31 (0)24 36 10989
>>
>> Email: c.hesse at fcdonders.ru.nl
>> Web: www.fcdonders.ru.nl
>> --------------------------------------------------------------------- 
>> -
>>
>>
>>
>>
>
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----------------------------------------------------------------------
Christian Hesse, PhD, MIEEE

F.C. Donders Centre for Cognitive Neuroimaging
P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands

Tel.: +31 (0)24 36 68293
Fax: +31 (0)24 36 10989

Email: c.hesse at fcdonders.ru.nl
Web: www.fcdonders.ru.nl
----------------------------------------------------------------------




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