sss.h File Reference

Declaration of the SSS class implementing Signal Space Separation (SSS) and temporal Signal Space Separation (tSSS) for MEG data. More...

#include "dsp_global.h"
#include <fiff/fiff_info.h>
#include <Eigen/Core>
#include <QVector>

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Classes
struct	UTILSLIB::SSSParams
	Implements Signal Space Separation (SSS) and temporal SSS (tSSS) for MEG data. More...
class	UTILSLIB::SSS
struct	UTILSLIB::SSS::Basis
	Precomputed SSS basis and projectors for a given sensor array. More...

Namespaces
namespace	UTILSLIB
	Shared utilities (I/O helpers, spectral analysis, layout management, warp algorithms).

Detailed Description

Declaration of the SSS class implementing Signal Space Separation (SSS) and temporal Signal Space Separation (tSSS) for MEG data.

Author

Christoph Dinh chris.nosp@m.toph.nosp@m..dinh.nosp@m.@mne.nosp@m.-cpp..nosp@m.org

Since

2.0.0

Date

March, 2026

LICENSE

Copyright (C) 2026, Christoph Dinh. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
• Neither the name of MNE-CPP authors nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Theory: Taulu, S., Kajola, M. (2005). "Presentation of electromagnetic multichannel data: The signal space separation method." J. Appl. Phys. 97, 124905.

Taulu, S., Simola, J. (2006). "Spatiotemporal signal space separation method for rejecting nearby interference in MEG measurements." Phys. Med. Biol. 51, 1759–1768.

SSS separates the MEG signal into contributions from internal sources (brain) and external sources (environmental noise) by decomposing sensor data into a basis of spherical harmonics. tSSS additionally removes internal-space components that correlate with the external subspace in sliding time windows, suppressing near-field artefacts (e.g. implants, dental work).

The spherical harmonic basis uses 4π-normalised real harmonics. Integration over each coil is approximated by a single-point model using the coil-centre position and normal direction from FiffChInfo (suitable for standard MEG; for sub-millimetre accuracy use FwdCoilSet).

Definition in file sss.h.