A comparative assessment of information-exploitation techniques for GPR data inversion

The inversion of Ground Penetrating Radar (GPR) data requires the development of suitable information-exploitation techniques that are able to extract as much as possible information on the unknown targets from the available measurements. An innovative singlefrequency (SF) inversion technique based on a deterministic conjugate-gradient (CG) minimization and the iterative multi-scaling approach (IMSA) is described. It is then shown how to improve the performances of the SF-IMSA-CG method by the introduction of an external frequency hopping (FH) iterative loop. On the one hand, the proposed FH-IMSA-CG method allows to exploit the intrinsic frequency diversity of wideband GPR measurements thanks to the FH strategy. On the other hand, the IMSA approach guarantees a significant reduction of the problem unknowns, providing an increased resolution within the identified regions of interest (RoIs). A numerical comparison shows the advantages of the FH-IMSA-CG over its single-frequency version. Moreover, the benefits of integrating the IMSA within the FH are verified by directly comparing the FH-IMSA-CG with its single-resolution (BARE) version (FH-BARE-CG).