Separation of Anthropogenic Noise and Extremely Low Frequency Natural Magnetic Field Using Statistical Features

This contribution is aimed at separating the anthropogenic noise from the natural magnetic field in the measurements recorded in a Extremely Low Frequency band station located in Sierra Nevada, Spain, to experimentally study Schu-mann resonances. First, we use a scheme based on Independent Component Analysis that provides unsatisfactory results. In order to achieve a better separation, we develop a new method by exploiting the information that statistical moments give us, under the assumption that the statistical distributions of the anthropogenic noise and of the natural magnetic field are different. This method consists of finding the rotation of the two original directions of the magnetometers (North-South and East-West) that maximizes or, equivalently, minimizes, the value of a certain statistical parameter. Our purpose is that this rotation is equal to that rotation which makes the anthropogenic noise completely disappear from one of the outputs, which we will show that always exists.