Background noise estimation using outer product expansion for ELF electromagnetic wave signal

This paper shows the denoising performance of the outer product expansion with non-linear filters for the background noise included in the extremely low frequency (ELF) electromagnetic (EM) waves. We have proposed novel source separation techniques based on an outer product expansion with non-linear filters. Some kinds of the algorithm for the outer product expansion and its effectiveness have been reported. However, the denoising accuracy for real data has not been shown in the conventional researches. In this paper, two algorithms for an outer product expansion are applied to conduct the suitable method for the background noise reduction problem of EM wave data. Two topics are discussed in this paper. The performance of background noise reductions for ELF EM data analysis is represented using an outer product expansion. Moreover, optimal parameters, which yields the accurate denoising for EM wave data, are introduced.