Method And Realization Of Ground Penetrating Radar Echo Signal Imaging And Wavelet Denoising

The GPR(Ground Penetrating Radar) has been widely applied in the fields like geophysical survey and its high resolution and fast imaging of underground object fast technology have been overwhelmingly recognized all around the world. However, the GPRs put into use in China almost all come from fremdness. Under this condition, it is very necessary for us to develop our own GPR. For this reason, at the very beginning of 1999, our lab began to develop our own GPR. In the project "Research of GPR" of our lab, one of the main tasks is that how to make the echo to display with the form of image, which was received by GPR, and processing the echo signal to improve the quality of data, which can provide clear echo image for further geophysical explain, thus it can make us observe and recognize underground objects.Wavelet transform is an analysis method for non-stationary signal in recent years, and it is considered as the breakthrough of Fourier analysis. It also get over the disadvantage of local weak time-frequency analysis existed in Fourier analysis, what's more, it can analyze signal in different time scales and frequency scales. Meanwhile, wavelet theory makes it clear that wavelet transform can make the energy of a signal concentrate on minor coefficients. Larger coefficients carry more energy, smaller coefficients carry less energy, which is the theory basis of wavelet denoising used in this paper.To begin with, this paper analyzes the data structure of GPR data, and state the realization of GPR echo signal imaging software. In addition, this paper works over the basic theory and character of wavelet denosing, introduces the application of wavelet threshold filter method in GPR echo signal denosing, taking into account the disadvantages of soft threshold and hard threshold, a improved method-half soft and half hard method is used to contribute bigger effect. At last, for the reason that the aim of signal processing in GPR is to give the exact geophysical explanation of echo image, we give thegeophysical explanation of echo image after denoising, which can judge the effect of wavelet denosing by an indirect way. To test the actual effect of echo image after denosing, we compare the depth of wall get from echo image after denosing with actual depth of wall.To sum up, the theory analysis and analysis result of survey data confirm that wavelet analysis can effectively apply to analyze the GPR echo signal, and provide better data for computing the depth of wall preventing hills along the Guangzhou, Meizhou, Shantou railways.