Abstract: A signal vector derivation apparatus receives measurement results from a plurality of sensors that receive signals each represented by a vector having a predetermined direction and measure triaxial components orthogonal to each other and derives the direction of the vector. The measurement results from the sensors are each proportional to a sum of the triaxial components of the vector multiplied, respectively, by first coefficients. The signal vector derivation apparatus includes a spectrum deriving section and a direction deriving section. The spectrum deriving section derives a spectrum obtained based on the measurement results from the sensors and a sum of the first coefficients multiplied, respectively, by second coefficients, the spectrum having local maximum values within voxels in which signal sources that output the respective signals exist. The direction deriving section derives the direction of the vector based on the second coefficients used to obtain the spectrum.

Abstract: A signal/noise determination apparatus includes a plurality of sensors, a determination model recording section, and a signal/noise determining section. The plurality of sensors measure a signal and a noise. The determination model recording section records a determination model used to determine whether components of results of measurement by the sensors expected with hypothetical signal information and hypothetical noise information are from a signal source or a noise source. The determination model is generated by machine learning with the measurement results, the hypothetical signal information, and the hypothetical noise information as training data. The signal/noise determining section determines whether components of the measurement results are from the signal source or the noise source based on the measurement results and the determination model.

Abstract: According to the present invention, a filtering apparatus includes an FIR filter that has multipliers arranged to multiply input digital data having their respective different input time points by respective variable tap coefficients. The variable tap coefficients are each switched from a first tap coefficient to a second tap coefficient sequentially for the input digital data from later to earlier input time points. The first tap coefficient is arranged to cause the FIR filter to serve as a low-pass filter with the cut-off frequency set at a first frequency. The second tap coefficient is arranged to cause the FIR filter to serve as a low-pass filter with the cut-off frequency set at a second frequency different from the first frequency.