Stratigraphic absorption compensation of GPR signal based on improved S-transform

The loss of the higher frequency components of electromagnetic wave due to soil absorption and attenuation results in GPR signal decrease rapidly in deep areas. High frequency compensation is one of most important ways to improve GPR data resolution. The S-Transform (or ST) has been widely used in digital signal processing since it was proposed. Here, improved S-transform to GPR data has been designed to enhance the deep reflection events. Firstly, GPR signals are transformed to S-transform coefficients trace by trace; then at each time sampling point, the frequency factors depended attenuation are extracted according to the soil layer feature; the S-transform coefficients are weighed by the factors to ensure energy equalization at different time sampling point. Numerical simulated and real GPR data are used for testing the proposal and its validity. According to the time-frequency spectrum analysis before and after ST treatment, almost the same energy distribution in lower frequency range is obtained, and the higher frequency components are obviously increased at deep area. The comparison demonstrates that the reconstructed GPR data from S-transform with appropriate weighting method can implement compensation absorption very well without Q value.