Method and device for recognizing and removing undesired artifacts in multichannel magnetic field or electric potential measurements

A multichannel measurement device arranged to recognize and remove undesired artifacts and sensor-specific interference signals in at least one measurement channel of a multichannel magnetic field or electric potential measurement, wherein the measurement device comprises

• a set of N measurement sensors arranged to record the N-dimensional signal at a spatial sampling rate exceeding the highest spatial frequencies in a signal of interest, so that n+m is smaller than N;
• and
• a data processing logic, which is arranged to receive and record, at an electronic processor, the N-dimensional signal from the set of N measurement sensors and record the signal at a temporal sampling rate exceeding the highest frequencies in a signal of interest and generate a basis defining an n-dimensional subspace of the N-dimensional signal space, wherein n is smaller than N, using, in the definition of the n-dimensional basis, a physical model of a Signal Space Separation method, or a statistical model based on the statistics of a recorded N-dimensional signal;
• characterized in that the data processing logic is further arranged to:
• form a combined (n+m)-dimensional basis by adding m signal vectors to the n-dimensional basis, each of these m signal vectors representing a signal present only in a single channel of the N-channel device,
• decompose the recorded N-dimensional signal into n+m components in the combined basis, and
• subtract, from the recorded N-dimensional signal, the components corresponding to the m added vectors in the combined basis;
• produce a modified N-dimensional signal by removing undesired artifacts and sensor-specific interference signals, via the electronic processor, based on the recorded N-dimensional signal;
• and
• output, via the electronic processor, the modified N-dimensional signal.

A computer program for recognizing and removing undesired artifacts and sensor-specific interference signals in at least one measurement channel of a multichannel magnetic field or electric potential measurement, wherein a measurement device comprises a set of N measurement sensors and a data processing logic, and wherein the computer program comprises program code which, when run on an electronic processor, is arranged to execute the steps of:

• receiving, at the electronic processor, an N-dimensional signal from the set of N measurement sensors;
• recording the N-dimensional signal;
• generating, via the electronic processor, a basis defining an n-dimensional subspace of the N-dimensional signal space, wherein n is smaller than N, using, in the definition of the n-dimensional basis, a physical model of a Signal Space Separation method, or a statistical model based on the statistics of a recorded N-dimensional signal;
• characterized in that the computer program is further arranged to execute the steps of:
• forming a combined (n+m)-dimensional basis by adding m signal vectors to the n-dimensional basis, each of these m signal vectors representing a signal present only in a single channel of the
• N-channel device,
• decomposing the recorded N-dimensional signal into n+m components in the combined basis, and
• subtracting, from the recorded N-dimensional signal, the components corresponding to the m added vectors in the combined basis;
• producing a modified N-dimensional signal by removing the undesired artifacts and sensor-specific interference signals, via the electronic processor, based on the recorded N-dimensional signal;
• and
• outputting, via the electronic processor, the modified N-dimensional signal;
• wherein the N-dimensional signal is recorded at a temporal sampling rate exceeding the highest frequencies in a signal of interest and at a spatial sampling rate exceeding the highest spatial frequencies in a signal of interest, so that n+m is smaller than N.