Show noise levels from empty room data

This shows how to use mne.io.Raw.compute_psd() to examine noise levels of systems. See 1 for an example.

# Author: Eric Larson <larson.eric.d@gmail.com>
#
# License: BSD-3-Clause

import mne

data_path = mne.datasets.sample.data_path()

raw_erm = mne.io.read_raw_fif(
    data_path / "MEG" / "sample" / "ernoise_raw.fif", preload=True
)

Opening raw data file /home/circleci/mne_data/MNE-sample-data/MEG/sample/ernoise_raw.fif...
Isotrak not found
    Read a total of 3 projection items:
        PCA-v1 (1 x 102)  idle
        PCA-v2 (1 x 102)  idle
        PCA-v3 (1 x 102)  idle
    Range : 19800 ... 85867 =     32.966 ...   142.965 secs
Ready.
Reading 0 ... 66067  =      0.000 ...   109.999 secs...

We can plot the absolute noise levels:

raw_erm.compute_psd(tmax=10).plot(
    average=True,
    spatial_colors=False,
    dB=False,
    xscale="log",
    picks="data",
    exclude="bads",
)

Effective window size : 3.410 (s)

References

1

Sheraz Khan and David Cohen. Note: magnetic noise from the inner wall of a magnetically shielded room. Review of Scientific Instruments, 84(5):056101, 2013. doi:10.1063/1.4802845.

Estimated memory usage: 168 MB