An Estimation Method of Magnetotelluric Impedance

Abstract

The invention provides a magnetotelluric impedance estimation method. The method comprises the following steps: performing Fourier transform on a time domain magnetotelluric signal measured from an observation station to a frequency domain; estimating initial impedance by using a least square method, obtaining an initial residual error, distinguishing various noises, obtaining a weight value corresponding to magnetic field normalization, obtaining estimated magnetotelluric impedance, judging a numerical value of a parameter for measuring whether the noise is close to Gaussian noise, outputtingthe impedance and the like. According to the method, impedance estimation is carried out on the basis of a noise weighting mode, the relation between noise and signals can be well utilized, weightingnormalization is carried out by utilizing the correlation, and Gaussian noise increased along with increase of signal strength is restored into Gaussian noise after weighting normalization; comparedwith a traditional least square method and a traditional steady method, the method based on noise weighting truly solves the problem that Gaussian noise is increased along with increase of signal strength.

Description

technical field [0001] The invention relates to the field of magnetotelluric signal processing, in particular to a method for estimating magnetotelluric impedance. Background technique [0002] The magnetotelluric method has been widely used in mineral exploration, geological exploration, deep structure, earthquake prediction, geothermal and so on. The magnetotelluric method mainly uses natural field sources to study the change of underground resistivity from shallow to deep. The exploration depth is large and the work is convenient. However, the use of natural field sources also makes the electromagnetic field signals observed by the magnetotelluric observations very weak, and are easily disturbed by various noises, which greatly affects the quality and application effect of the magnetotelluric data. Therefore, how to suppress the interference and obtain an unbiased estimate of the magnetotelluric impedance has always been a hot topic in the field of magnetotelluric discus...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a kind of estimation method of magnetotelluric impedance, directly utilize noise itself to carry out weighting, be used for solving the problem existing in the data in the measured magnetotelluric (being because there are different noise sources in the same frequency band or noise increases with signal intensity and the problem of non-Gaussian noise brought by the increase), finally a good unbiased magnetotelluric impedance estimate is obtained

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