Cleaning MEG/OPM data with SSP from empty

Hi everyone,

Do you think is a good idea use mne.compute_proj_raw() as suggested in

for MEG/OPM data cleaning?

For this purpose I’m using an empty recording performed just after the subject recording. From literature in the same device they used n_mag=4 (there are only mag channels, not grad as in “normal” meg), for me it also has seemed a good option to remove enviromental noise since with n_mag=2 (or 3) is still possible to see some undesired peaks at the 20-30 band in the spectrum.