Proc. SPIE. 4742, Detection and Remediation Technologies for Mines and Minelike Targets VII
KEYWORDS: Target detection, Finite-difference time-domain method, Reflection, Dielectrics, Surface roughness, Receivers, Monte Carlo methods, Signal processing, Land mines, General packet radio service
In ground penetrating radar (GPR) antipersonnel mine sensing, in which the target is small, shallow and often of low dielectric contrast, detection is challenging. One of the difficulties is that it is hard to distinguish the target signal from the omnipresent random rough ground reflection clutter. In this work, a Monte Carlo computational simulation using 2-dimensional (2-D) transverse magnetic (TM) finite difference time domain (FDTD) with multiple rough surfaces is implemented to investigate single TNT target buries in dispersive soil. Based on the effects of the random rough surface on an impulse GPR signal and the knowledge of wave propagation differences in different media - air, soil, and TNT - a special background average process using physics based signal processing (PBSP) is performed to remove the ground clutter signal. This procedure first involves shifting and scaling multiple time signals from target-free random rough ground to establish the nominal (average) ground reflection pulse shape. Next, this nominal pulse shape is correlated in time with each trial signal, then shifted and scaled to match the ground surface clutter of that trial signal. Subtracting this shifted scaled clutter signal from the trial signal ideally leaves the target signal (with some additional multiple scattering between the target and ground surface). The PBSP algorithm reapplied in cases for which surface scattering occurs at multiple points. The statistical results of PBSP surface clutter removal indicate that the detection performance degrades with increasing surface roughness and decreasing burial depth. Hypothesis testing on the processed results proved to be successful in a detection and estimation point of view. This paper presents the detection performances in terms of Receiver Operating Characteristics (ROC) for various ground surface roughness and target burial depth cases. Also demonstrated is the performance improvements expected from multiple views: indicating that a multi-bistatic configuration appears to be superior to multistatic transmitter/receiver geometry with minimum combinations.