cannot convert gradiometer definition back to axial, please contact Robert

Sameer Walawalkar sameer at ANDREW.CMU.EDU
Thu Jun 14 21:22:14 CEST 2007


Hi,

As suggested I did freqanalysis and followd it up by trying combine planar
and got similar error.

cfgTFR = [];
cfgTFR.output       = 'pow';
cfgTFR.channel      = 'MEG';
cfgTFR.method       = 'mtmconvol';
cfgTFR.foi          = 5 : 5 : 90;
cfgTFR.t_ftimwin    = 5./cfgTFR.foi;
cfgTFR.tapsmofrq    = 0.4 *cfgTFR.foi;
cfgTFR.toi          = .0 : 0.05 : .5;
cfgTFR.pad          =  'maxperlen';

and

cfg = [];
cfg.combinegrad = 'yes';

ERROR message:

the input is freq data with 306 channels, 18 frequencybins and 11 timebins
Warning: trying to convert planar to axial gradiometers, this is
experimental
> In combineplanar at 280
   In Auto_nonparametric_coh at 47
??? Error using ==> combineplanar
cannot convert gradiometer definition back to axial, please contact Robert

Error in ==> Auto_nonparametric_coh at 47
TFR_LL_000_500_cmb = combineplanar(cfg, TFR_LL_000_500);


thanks,
sameer




On Mon, 11 Jun 2007, Robert Oostenveld wrote:

> Hi Sameer,
>
> On 7 Jun 2007, at 22:11, Sameer Walawalkar wrote:
>
>> Hello Robert,
>>
>> I have been playing around with
>> http://www2.ru.nl/fcdonders/fieldtrip/doku.php?id=fieldtrip:documentation:tutorial:statistics#3_permutation_tests_for_time-frequency_representations
>>
>> in an attempt implement non-paramteric statistical testing of coherence
>> diferences between trials. My screen currently reads:
>>
>> the input is freq data with 612 channels, 18 frequencybins and 11 timebins
>
> How did you manage to get 612 channels? Are you computing planar channels
> from your planar channels? Your neuromag system already has planar channels
> (by hardware design), hence you should not call megplanar on your data. The
> megplanar function is meant for computing planar gradients from a hardware
> magnetometer system (or a hardware axial gradiometer system, such as our
> CTF).
>
> After preprocessing and timelockanalysis or freqanalysis you should do
> combineplanar.
>
>> Warning: trying to convert planar to axial gradiometers, this is
>> experimental
>>> In combineplanar at 280
>>  In Auto_nonparametric_coh at 47
>> ??? Error using ==> combineplanar at 308
>> cannot convert gradiometer definition back to axial, please contact Robert
>>
>> Error in ==> Auto_nonparametric_coh at 47
>> TFR_LL_000_500_planar_cmb = combineplanar(cfg, TFR_LL_000_500_planar);
>>
>>
>> So, I am getting in touch with Robert Oostenveld.
>
> best regards,
> Robert
>
> ----------------------------------
> The aim of this list is to facilitate the discussion between users of the
> FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and
> EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and
> http://www.ru.nl/fcdonders/fieldtrip.
>

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/fcdonders/fieldtrip.



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