A Research Of Signal Extracting Method Used In Engineering Geophysics

This paper analyzes the principle of common geophysical prospecting methods from the present situation of engineering geophysics,and points out that the existing method is based on energy criterion.The shortcomings of the method of extracting signal by the energy criterion are listed: 1,the echo signal must be clearly visible;2,the signal from weak reflective layer is difficult to identify;3,the attenuation of the source seriously interfere with the reflection signal;4,the signal from thin reflective layer is difficult to identify.This paper introduces a new method to recognizing and extracting echo signal,by demonstrating the characteristics of signal phase domain.It is hoped that this method can solve the problems above.In order to achieve the above goal,this paper uses S Transform and S inverse transform to denoising the original signal;secondly,uses Hilbert-Huang transform to analysis the phase of the processed signals,and extracts suitable instantaneous phase information of echo signals;at last uses the wavelet transform technique to extract and identify echo signal from the instantaneous phase information.On the basis of theoretical analysis,this paper completes the whole method which combines three kinds of transformations,and calculates over model signal,and verifies its performance in extracting echo signals of weak reflective layer and thin reflective layer.In the process of the actual signals of nondestructive testing of anchor rods,nondestructive testing of piles,geophysics radar,this method can provide more accurate time information of reflection signals than the traditional method,and further verifies the feasibility and validity of the method of signal recognition and extraction from the practical point of view.