Service tools🔗

The DACQ contains many useful service tools that can help in the daily MEG activity.

autonoises🔗

The autonoises tool is used to measure the noise level in the MEG room and to auto-detect noisy or out of range channels. This tool runs on an empty-room recording.

$ /neuro/dacq/tools/noise/autonoises emptyroom_68.fif

dossp🔗

The dossp tool is used to compute SSP projectors from an empty-room recording. The tool will:

  • Select a channel type

  • Apply filters (by default, low-pass @ 48 Hz)

    Note

    The filters do not retain the line frequency noise on purpose. Line frequency is rarely corrected by SSPs projector.

    Note

    It might be better to remove the DC component with an (0.1, 48) Hz bandpass filter.

  • Compute the covariance matrix

  • Compute the PCA decomposition of the covariance matrix and keep the first N components (8 by default)

  • Removes components which are locked on a sensor

$ /neuro/dacq/tools/noise/dossp emptyroom_68.fif

Note

The filters parameters differ from MNE’s default which yields differences in the obtained projectors between dossp and MNE’s function compute_proj_raw(). Moreover, our site has a strong 16.7 hz noise coming from the railway electrificatin system. This artifact can be very well captured by 1-3 components estimated on the narrowband 15-18 Hz. The projectors from the narrow and wideband PCA can be combined to form an orthogonal basis.

autophantom🔗

Autophantom automatically fits the measured dipoles with xfit and compares it with the known true position of each individual dipole. It requires an evoked (average) FIFF file as input.

$ /neuro/dacq/tools/service/autophantom phantom_avg.fif --pdf