De-noising method of transient electromagnetic detecting echo signal

Abstract

The invention provides a de-noising method of a transient electromagnetic detecting receiving signal, which comprises the following steps of: decomposing a transient electromagnetic detecting receiving signal by means of empirical mode, i.e. 'screening'; leading all extreme points of signal data x (t) to form into an upper envelope and a lower envelope through a cubic spline interpolation function; obtaining a mean value m1, wherein a first component h1=x (t)-m1, and the h1 is regarded as data to be processed to repeat the screening with k times; obtaining a first IMF when the standard deviation SD of the continues twice screening results meets the requirement, wherein c1=h1k=h1(k-1)-m1k and a residual signal r1; repeatedly 'screening' the r1; decomposing signal data to be n IMFs and one residual quantity rn; judging signal dominant and noise dominant component according to the diminishing condition of each IMF energy; and accumulating again after filtering each IMF of the signal dominant to obtain the de-noised signal. The method adopts empirical mode decomposition of adaptive time-frequency analysis, does not need priori information, respectively processes the different natural frequencies of the signal, removes high-frequency noise, filters high-frequency noise, is applied to removing the noise of the non-linear and non-stationary transient electromagnetic detecting echo signal, and is patricianly applied to removing the noise of a deep echo signal.

Description

(1) Technical field [0001] The invention relates to transient electromagnetic detection technology, in particular to a noise reduction method for transient electromagnetic detection echo signals based on empirical mode decomposition. (2) Background technology [0002] As we all know, the principle of transient electromagnetic detection is: the transient electromagnetic wave is attenuated by different media in each formation during the process of propagating underground, and different media have different attenuation values ​​for transient electromagnetic waves of different frequencies. Therefore, as long as the characteristic spectrum of the transient electromagnetic signal corresponding to different substances in the echo signal is extracted, the different substances in the formation can be inverted. However, the geological remote sensing signal is non-stationary and the background noise is complex. Using the conventional time-frequency joint analysis method will generate f...

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Problems solved by technology

[0005] For the deep echo signal, the noise is many times larger than the target signal. No matter how the integral stacking method increases the stacking times, the final signal is still dominated by noise, because the integral stacking method cannot eliminate the noise of the deep echo signal. Therefore, this method cannot be used to extract the target signal of deep geological conditions, and the deep geological characteristics cannot be accurately obtained

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