mne_compensate_data

Overview

mne_compensate_data applies or changes the software gradient compensation grade in CTF MEG data stored in FIFF format. CTF systems use reference channels to reduce environmental noise via software gradient compensation. This tool allows switching between compensation grades.

This is a C++ port of the original MNE-C tool by Matti Hämäläinen.

Usage

mne_compensate_data [options]

Options

Option	Description
--in <file>	Input raw FIFF file
--out <file>	Output FIFF file
--grade <value>	Desired compensation grade (0, 1, 2, or 3)
--help	Print help
--version	Print version

Description

CTF MEG systems employ software gradient compensation to reduce environmental noise. The compensation grade determines the order of the spatial gradient applied. Grade 0 means no compensation, while grades 1–3 apply successively higher orders of noise cancellation using reference channels.

This tool reads a raw FIFF file, applies the requested compensation grade, and writes the result. The input file must be a CTF dataset that has already been converted to FIFF format (e.g., with mne_ctf2fiff).

Workflow Context

After converting CTF data to FIFF format with mne_ctf2fiff, you may need to change the compensation grade before further processing. Grade 3 is the most common choice for source localization. The compensated file can then be processed with mne_process_raw or used directly for inverse solutions.

Example

# Apply 3rd-order gradient compensation
mne_compensate_data --in ctf_raw.fif --out ctf_raw_comp3.fif --grade 3