Most civilized nations ban the use of landmines because they kill indiscriminately, and for years after they are planted. However, they are still used in many places around the world, and people are still left trying to find better ways to find and remove them. This group is looking at an interesting new approach: using ground-penetrating radar from a drone [PDF link]. The idea is that you send out a radio signal, which penetrates into the ground and bounces off any objects in there. By analyzing the reflected signal, so the theory goes, you can see objects underground. Of course, it gets a bit more complicated than that (especially when signals get reflected by the surface and other objects), but it’s a well-established technique even though this is the first time we’ve seen it mounted on a drone. It’s a great idea: the drone allows you to have the transmitting and receiving antennas separated with both mounted on pole extensions, meaning that the radio platform can move. Combined with a pre-planned flight, and we’re looking at a system that can fly over an area, scan what is under the ground, and store the data for analysis.
This team includes [J. Rodriguez], [C. Castiblanco] [I. Mondragon] and [J. Colorado] at the Pontificia Universidad Javeriana in Bogotoa, Colombia. This team attached an Ettus URP B210 SDR card with two Vivaldi antennas to an Astec Firefly drone, linked via WiFi to a Linux server for the heavy data analysis in GNURadio. The two antennas were located on either side of the drone, attached to a crossbar that separated them and also held the Ettus SDR device.
The trials on the device look promising: the team was able to detect several metal objects in a number of different soil types. The soil type and moisture level is a big part of the problem here: it affects the transmission of the radio signal, and thus the object detection. It’s a promising project that has potential: as the writers note, the use of an SDR system means that the radio detection system can be reconfigured, literally, on the fly. That means it could be adapted to different soil types, and even to detect different sized objects.