Study on attenuation of strong surface wave in wavelet domain

The threshold method suppressing surface wave based on discrete wavelet transform (DWT) is suitable for the character of minority scale de-noise that the frequency bands of surface wave and reflections are overlap. The paper uses theoretical model to analyze and compare the influence of four rules of threshold selection on suppressing surface wave by DWT threshold method, and chooses optimum rule. On that basis, first, using improved DWT threshold method to suppress surface wave preliminarily, then, using combining 2-D physical wavelet frame denoise (PWFD) to suppress residual energy of surface wave. The theoretical record and practical data processing showed that in combining with PWFD threshold denoise, the DWT threshold denoise can better both suppress the surface wave and make the useful signal fidelity. The denoise effect by the method is superior to that by f-k method and other denoise methods.