Study On The MT Signal Processing With Adaptive Filtering

Magnetotelluric (MT) method which was a method for studying the electrical characteristics and its relative distribution has been widely used in geophysical prospecting. During the data acquisition in MT prospecting; the affection of the noise could be avoided due to which impedance estimation would suffer from a deviation. The reliability and accuracy for interpreting the earth structure and the electrical distribution would be greatly influenced. Therefore, how to suppress the various electromagnetic noises to increase the Signal-to-noise Ratio (SNR) for obtaining the reliable impedance estimation in MT surveying has become an essential target of the data acquisition and processing for MT signal.In this paper, Adaptive filtering theory was applied to MT signal de-noising processing. The main research was focused on the adaptive filter algorithm and suppressing power line interference and vibration disturbance in the acquisition of MT signal. And the main content in this paper was organized as follows:First, MT method and characteristics of natural electromagnetic field signal was introduced. Second, the noises which commonly appeared in MT sounding and their impact on the impedance estimation were summarized. Third, a systematical review about the basic principles of adaptive filter theory and typical applications was made. Much attention was focused on the LMS algorithm and RLS algorithm and their performances. Forth, Simulation for the LMS algorithm and RLS algorithm to select the parameters and analyzing their characteristics of the corresponding adaptive filter was implemented. Finally, both of the two algorithm applied in MT signals were carried out. The results has validated the application of adaptive filter theory in MT signal de-noising processing.