Time Frequency Analysis!

Wed Feb 21 13:14:40 CET 2007

Hello JM,

The time axis in my data which i define from 0 to 30 secs

data1.time{1,1}=0:0.0375:29.99875;

after making the changes it works now but i get the only values from

0.125 to 0.625 and all the other values are Nan's

thanking you

with regards
M.Muthuraman.

>From: Jan Mathijs Schoffelen <Jan.Schoffelen 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: Wed, 21 Feb 2007 12:41:24 +0100
>
>What's the time-axis in your data?
>
>JM
>
>-----Original Message-----
>From: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] On Behalf
>Of Muthuraman Muthuraman
>Sent: Wednesday, February 21, 2007 12:16 PM
>To: FIELDTRIP at NIC.SURFNET.NL
>Subject: Re: [FIELDTRIP] Time Frequency Analysis!
>
>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://
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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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