Comparison of Scanning Strategies in UAV-Mounted Multichannel GPR-SAR Systems Using Antenna Arrays

Abstract

Ground Penetrating Radar (GPR) systems on board Unmanned Aerial Vehicles (UAVs) have been successfully used for subsurface imaging applications. Their capability to detect buried targets avoiding the contact with the soil turn these systems into a great solution to detect buried threats, such as landmines and Improvised Explosive Devices (IEDs). Significant advances have been also conducted to enhance the detection capabilities of these systems, complementing the Synthetic Aperture Radar (SAR) processing methods with several clutter mitigation techniques. However, the improvement in the scanning throughput (i.e., increasing the inspected area in a given time) remains a significant challenge. In this regard, this article compares several scanning strategies for UAV-mounted multichannel GPR-SAR systems using antenna arrays. In particular, two different scanning strategies have been compared: a uniform scheme and a non-uniform strategy called 3X. In addition, different acrosstrack spacing values to generate dense and sparse sampling distributions were considered for each scanning scheme. After conducting a theoretical analysis of these strategies, they have been experimentally validated with measurements gathered with a portable scanner and during flights in realistic scenarios. Results show that the dense configurations of both scanning strategies yield good quality images of buried targets while improving the scanning throughput (compared to a singlechannel architecture). In particular, the dense uniform scheme (with a 20 cm across-track spacing) achieves a greater reduction in the inspection time, compared to the dense 3X strategy, at the expense of a slightly smaller signal to clutter ratio.

Real-Time Synthetic Aperture Radar Imaging with Random Sampling Employing Scattered Power Mapping

“…Their potential as platforms for SAR imaging is due to the remarkable progress of the positioning technology, which now provides accurate platform coordinates. The convergence of UAVs with ground-penetrating radars (GPRs) [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ], operating at wavelengths as short as 73 mm, necessitates positional accuracy at the centimeter or millimeter scale for effective imaging. This accuracy, akin to trajectory accuracy in remote sensing, is of paramount importance since errors as small as a fraction of a wavelength lead to pronounced image distortions.…”

“…To this end, a few image-reconstruction algorithms based on the back-projection (or back-propagation) algorithm (BPA) have been proposed [ 24 , 27 , 29 , 47 , 48 ]. The BPAs, when applied in real space, can inherently handle any sampling position; thus, they are preferred in the case of nonuniform and random sampling.…”

Enhancement of penetration of electromagnetic waves by field focusing applied to GPR detection

“…Owing to its non-destructive nature, high-resolution imaging capabilities, and ease of operation, ground penetrating radar (GPR) is extensively applied in underground pipe detection, infrastructure inspection, and engineering projects [1][2][3][4]. However, when operating in lossy dielectrics, GPR is limited by challenges such as high signal attenuation and inadequate target detection capabilities [5][6][7].…”