Comment on: “Fast 3D inversion of gravity data using solution space priorconditioned Lanczos bidiagonalization”, by Mohammad Rezaie, Ail Moradzadeh and Ali Nejati Kalateh

Abstract

To reduce the shielding effect of strong jamming signals such as direct waves and multiple echoes on the effective signals in ground penetrating radar (GPR) images and effectively improve the GPR image resolution, a method to remove strong interference signals in GPR that combines the wavelet transform and F-K filtering is proposed. First, we choose a biorthogonal wavelet basis that matches the waveform of GPR signal, and an original GPR image is decomposed into subimages of different frequency bands based on the optimal wavelet basis. Second, according to the difference in the distribution of the effective signals and the strong interference of different subsignal images in the wavenumber domain, different bandpass filters are designed to accurately separate the effective signals and strong interference, and the subimages are reconstructed after the interference being removed. The processing of the forward simulated and measured GPR images shows that the combined method of wavelet transform and F-K filtering can produce different F-K filters according to the characteristics of different subsignal images and accurately process the image, suppressing the strong interference and retaining the effective signals to the greatest extent. Compared to the results of the predictive deconvolution method and the conventional F-K method, the cavity reflection in the image processed by the proposed method is more obvious, the coaxial signal is continuous and clear, and the image resolution is improved, which proves the feasibility and effectiveness of this method in separating strong interference waves.