[Mne_analysis] maxwell filtering 4D-neuroimaging/BTi data

[Helge Ahrens]

        External Email - Use Caution        

Dear Maria,

I’m not one of the MNE experts but have some ideas about how MaxFilter should work.
Could you check some things:

  *   Are there some bad channels left that could be spread noise into the entire sensor field by the MaxFilter? For example sensor A248 looks like that you should mark it as bad and let MaxFilter reconstruct it based on the remaining good channels.
  *   Are the correct calibration files of the MaxFilter used? Wrong calibration files could also introduce disturbances into the data.
I hope that might help.

Best regards
Helge

-------------------------------------------------------------
Helge Ahrens

Neuroimaging
Carl-von-Ossietzky University
26111 Oldenburg
Germany
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Website: https://uol.de/neuroimaging/

From: mne_analysis-bounces at nmr.mgh.harvard.edu <mne_analysis-bounces at nmr.mgh.harvard.edu> On Behalf Of Maria Hakonen
Sent: Montag, 3. Dezember 2018 08:20
To: Discussion and support forum for the users of MNE Software <Mne_analysis at nmr.mgh.harvard.edu>
Subject: [Mne_analysis] maxwell filtering 4D-neuroimaging/BTi data


        External Email - Use Caution
Dear MNE experts,

I tried to maxwell filter meg data collected with 4D-neuroimaging/BTi system as follows:
raw_tsss = mne.preprocessing.maxwell_filter(raw, st_only=True, ignore_ref=True,destination=trans,st_duration=60)

raw_sss = mne.preprocessing.maxwell_filter(raw, st_only=False, ignore_ref=True,destination=trans)

However, the data looks very noisy after filtering:

Original data:
[original.png]
sss filtered data:
[maxfiltered_SSS.png]
tsss filtered data (left) and original data (right):
[original_vs_maxfiltered.png]

I wonder if anyone knows what could be wrong?
Is it a problem if there are discontinuities in the data (all data is not collected on the same day).

Best,
Maria
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