Time Frequency Analysis!

[Muthuraman Muthuraman]

Hello,

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;
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://
>>messenger.msn.com/Download/Default.aspx?mkt=en-in
>>
>
>----------------------------------------------------------------------
>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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