Our group has been using Ground Penetrating Radar (GPR) for detecting and locating buried objects. GPR is a non-invasive sensor and has been applied for clearance of Unexploded Ordnance (UXO) buried under permeable iron-rich volcanic soil in Hawaii [15]. Conventional magnetic sensors were found to produce very poor detection performance in permeable environments due to severe background noise caused by high permeability of such soils. GPR systems, however, can provide desired features even in permeable soils where other magnetic sensors (e.g. EMI and magnetometers) could not function properly.

An ultra-wide bandwidth (UWB), dual-polarized GPR system and an advanced classification algorithms have been developed by our group (see Fig. 1a). Based on initial test results, it is shown that the system can provide target information such as position, orientation, depth, length, linearity or inclination from data collected at multiple passes over the target (see Fig. 1b). Also, a UWB GPR with proper processing algorithms can reject a large amount of small metallic debris that presents serious problems in classification and data analysis. Proper (UWB, low-antenna clutter, multiple-positions) GPR data also has superior spatial and temporal (or depth) resolutions that allow one to determine the presence of interfering objects or to separate the individual responses

We will continue to investigate the scattering characteristics from various type of UXO under different soil conditions and develop an effective UXO classification method using GPR. Based on FDTD simulation results and experimental measurements in a GPR test-bed and actual fields, special scattering features discriminating UXO from clutters can be extracted and applied to detection algorithm. Effective post-processing algorithms enhancing reliability of the classification will also be developed using the artificial intelligent technologies. Eventually, autonomous GPR UXO classification system, which minimizes detection error and increases classification speed, will be developed.