Skip to content

Noisy Data

If Acquired data is noisy during Acquisition, run a quick check to see if the artefacts can be easily removed using MaxFilter.
Collect ~1min or so of data, save, and then …

  1. Start MaxFilter.
    • Applications -> Neuromag -> MaxFilter.
    • Dismiss the "Welcome" splash screen, click "Hide"
  2. File -> Working directory.
    • Example settings files/.fif files, to try, are shown in blue.
  3. In the Select a new working directory window, type the name of the folder location e.g.
    • /data/neuro-data/demo/221003/ - don’t forget the “/” at the end!
  4. Click “OK"
  5. File -> Load data.
  6. In the Files window, select the relevant .fif file e.g.
    • watch_on_chair_30_sec.fif
  7. In the Maxwell filtering task window, select Spatiotemporal tSSS
    • "to suppress nearby movement-related artefacts such as metal fillings/a magnetised tooth."
  8. Click “OK”.
  9. Click “Execute”.
  10. File -> Exit
  11. Click “Yes”.
  12. A file should now have been written to the working directory location, with the addition of “_tsss” to the name of the .fif file chosen in Step 6 above e.g.
    • watch_on_chair_30_sec_tsss.fif

Info

For more detailed information on usage,
please read pages 21 – 25 from Guidelines to MEG Data Analysis Software

Compare the before and after MaxFilter files …

  1. Start Graph.
    • Applications -> Neuromag -> Graph.
    • Dismiss the "Welcome" splash screen, click "OK".
  2. File -> Load settings.
    • Example settings files/.fif files, to try, are shown in blue.
  3. In the Directories window, double-click on the settings required e.g.
    • /home/meguser/lisp/setup/local.
  4. In the Files window, select compare.setup
  5. Click “OK” - two synchronised Windows will appear.
  6. In the top Window, File -> Open Diskfile
  7. In the Directories window, double-click /neuro/data/sinuhe
  8. In the next Directories window (left-click on the RH window edge and drag to open the window wider if necessary), scroll down and double-click on the Project e.g.
    • /neuro/data/sinuhe/demo
  9. In the next Directories window (left-click on the RH window edge and drag to open the window wider if necessary), scroll down and double-click on any relevant sub-directory e.g.
    • /neuro/data/sinuhe/demo/221003
  10. In the Select disk file to open window, chose the unfiltered .fif file e.g.
    • watch_on_chair_30_sec.fif
  11. Click “OK".
  12. In the top Window, Displays -> Control Panel
  13. Open the filtered .fif file by double-clicking the widget "File2" (usually to be found bottom left of the Control Panel window).
  14. Repeat from Step 7 to Step 10 to select the "… _tsss.fif" file e.g.
    • watch_on_chair_30_sec_tsss.fif
  15. Click “OK"
  16. View the effect of MaxFilter on the original noisy .fif file (lower window/display2).
  17. In the top Window, "Exit", "Exit", "Yes", when finished.

Info

For more detailed information on usage,
please read from page 57 onwards, as necessary, from Guidelines to MEG Data Analysis Software