[FieldTrip] different gradiometer-units from fiff-file

Michael Scholz scho at med.ovgu.de
Wed Mar 8 17:52:46 CET 2017

Dear community,

My name is Michael Scholz and I am working in Magdeburg (Germany) 
in the Department of Neurology. 
We just started using our Elekta Neuromag Triux System. 
I was going to use fieldtrip to create some simulation data to 
test Elekta software. Therefore I read data from a fiff-file acquired 
by the Elekta-MEG-system including 102 magnetometer-data and 2x102 
gradiometer data. 
Reading fiff-files with ft_read_data creates output with magnetometer-data 
in Tesla (T) and gradiometer-data in T/m  just as in the fiff-file. 
Reading the same fiff-file by ft_read_sens creates a structure with 
header-info including T/cm-unit-info for the gradiometer-sensors.
This was not expected and was misleading; if one doesnt recognize 
these different units for the gradiometers and combines data based 
on ft_read_sens-output and ft_read_data-output, the result is unusable, 
since scaling of magnetometer-data and gradiometer-data wont match.

How can I prevent ft_read_sens from reading gradiometer in different 
units as given in the source-fiff-file?


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