Ground roll attenuation using real and complex DWT based methods

This paper deals with ground roll attenuation using double density and dual-tree complex discrete wavelet transforms. These transforms use a new denoising method instead of well-known hard and soft thresholdings and Wavelet Domain Ground roll Analysis (WDGA) applied in finding and attenuating the ground roll energy in the wavelet domain. The dual-tree complex wavelet transform (DTCWT), and double density discrete wavelet transform (DDDWT) have two wavelets and one scaling function and are nearly shift-invariant. Also they have redundancy factors of 2, and their wavelets are smoother than other orthogonal wavelets. Based on this fact, they can be considered as replacement methods for such aims. Recognizing the performance of each method is required to show which method is more suitable and efficient. In the present study, distinct wavelets and scaling function of each method have been applied to the data, and also the data are denoised by Wavelet Domain Ground roll Analysis technique. Additionally, for the inverse transform, the coefficients of the noise are removed. And finally for concluding, the results of all methods are compared with the f-k method and band-pass filtering, and critically sampled Discrete Wavelet Transforms. Final results showed that the DTCWT is reliable in comparison with other methods for ground roll attenuation. (C) 2014 Elsevier Inc. All rights reserved.