Landmines Ground-Penetrating Radar Signal Enhancement by Digital Filtering

Abstract

Abstract-Until now, humanitarian demining has been unable to provide a solution to the landmine removal problem. Furthermore, new low-cost methods have to be developed quickly. While much progress has been made with the introduction of new sensor types, other problems have been raised by these sensors. Ground-penetrating radars (GPRs) are key sensors for landmine detection as they are capable of detecting landmines with low metal contents. GPRs deliver so-called Bscan data, which are, roughly, vertical slice images of the ground. However, due to the high dielectric permittivity contrast at the air-ground interface, a strong response is recorded at an early time by GPRs. This response is the main component of the so-called clutter noise, and it blurs the responses of landmines buried at shallow depths. The landmine detection task is therefore quite difficult, and a preprocessing step, which aims at reducing the clutter, is often needed. In this paper, a difficult case for clutter reduction, that is, when landmines and clutter responses overlap in time, is presented. A new and simple clutter removal method based on the design of a two-dimensional digital filter, which is adapted to Bscan data, is proposed. The designed filter must reduce the clutter on Bscan data significantly while protecting the landmine responses. In order to do so, a frequency analysis of a clutter geometrical model is first led. Then, the same process is applied to a geometrical model of a signal coming from a landmine. This results in building a high-pass digital filter and determining its cutoff frequencies. Finally, simulations are presented on simulated and real data, and a comparison with the classical clutter removal algorithm is made.

A Simple Strategy to Detect Changes in Through the Wall Imaging

“…A similar filtering is exploited in ground penetrating radar (GPR) imaging [16] where a high-pass filtering suppresses the low harmonic spatial content in order to mitigate the clutter arising from the air/soil interface.…”

“…Indeed, all the scatterers are assumed to be at rest during data acquirement. Moreover, they have all a finite spatial support hence filtering the spatial spectrum as in [16] is not useful.…”

“…a similar filtering as in [16] can be applied if data are Fourier transformed with respect to the discrete variable m. Here, we adopt a different procedure where the change detection is achieved by means of the difference between two different tomographic reconstructions of the same spatial region.…”

Information Theoretic Criterion Based Clutter Reduction for Ground Penetrating Radar

“…A digital filter, whose coefficients are optimized with respect to the signal spectrum, is used for clutter reduction. However its limitation includes optimum selection of filter coefficients [6]. Another approach called earlytime gating (which consists of eliminating early data samples of all traces) [7] is based on the assumption that the antenna coupling and surface reflections arrive early in time domain compared to the target signals.…”

Generalized two-sided linear prediction approach for land mine detection

“…Some of them are the hidden Markov model (HMM) [2] that is designed to detect the hyperbolic signature produced from a land mine, the least mean square (LMS) algorithm [3] that detects anomaly in the soil background, and the principal component analysis (PCA) [4] that is used to model the soil background. Enhancing land mine signal through digital filtering is proposed in [5]. Feature based algorithms together with training are also developed recently [6]- [8].…”