Enhancing signal-to-noise ratio of magnetotelluric responses by directional filtering

Abstract:

The magnetotelluric (MT) method generally suffers from a low signal-to-noise ratio (S/N), particularly in some frequency bands, due to the presence of a variety of sources for natural and cultural noise. A significant contribution to noise in the data is caused by localised cultural sources such as mining areas, electric fences and television transmitters. Accordingly, S/N can be improved by filtering and subsequently rejecting signals arriving at the recording station from the direction of these sources. Usually MT data is Fourier transformed and estimates of the electric impedance are made in the frequency domain. But the Fourier transformation (FT) method has low sensitivity to non-stationary signals (variable over the recording time) and is not able to determine the arrival time of a signal. This can be overcome by either dividing the record into shorter segments of time, performing the FT for each of the subsets and …

Año de publicación:

2009

Keywords:

Fuente:

google