The Peregrine Is an Aerial Drone That Peers Below the Antarctic Ice with an SDR and a Raspberry Pi
Designed to look under the ice, rather than just at the surface, a fleet of these Raspberry Pi-powered drones could provide valuable data.
Researchers from the Stanford Radio Glaciology lab have built an uncrewed aerial vehicle (UAV) with a difference: it's designed to peer under the ice using a software-defined radio (SDR) radar system and a Raspberry Pi.
"Peregrine is a modified UAV carrying a miniaturized ice-penetrating radar that we designed around a software-defined radio," explains Thomas Teisberg, in a piece for IEEE Spectrum, on the machine he and colleagues have created. "The radar system weighs under a kilogram—featherweight compared with conventional IPR [Ice-Penetrating Radar] systems, which take up entire equipment racks in crewed aircraft. The whole package — drone plus radar system — costs only a few thousand dollars and packs into a single ruggedized case, about the size of a large checked bag."
The idea is to be able to augment surface-level measurements from orbital satellites with information about what's happening underneath the ice — depth, fractures, fissures, melt flow, and the like. Traditionally, gathering these data has been a laborious manual process — but Peregrine, and devices like it, promise to make it considerably easier.
The Peregrine payload is based on off-the-shelf software-defined radio (SDR) hardware linked to the Ettus Research USRP Hardware Driver, forming the radar system for looking below the surface of the ice. The radio itself is controlled by a Raspberry Pi single-board computer, which also monitors the drone's health through a series of temperature sensors.
"For the drone, we started with a kit for an X-UAV Talon radio-controlled plane, which included a foam fuselage, tail assembly, and wings," Teisberg explains. "We knew that every piece of conductive material in the aircraft would affect the antenna's performance, perhaps in undesirable ways. Tests showed that the carbon-fiber spar between the wings and the wires to the servo motors in each wing were creating problematic conductive paths between the antennas, so we replaced the carbon-fiber spar with a fiberglass one and added ferrite beads on the servo wiring to act as low-pass filters."
After 3D-printing a housing for the Raspberry Pi and lining it with copper to shield the sensitive radio system from electrical noise, the Peregrine proved its worth in field tests — and forms the basis of a plan for a larger ice-penetrating radar drone design, which could be deployed from the 11 existing Antarctic research stations to cover the entire region. "Though larger and more expensive than our original Peregrine," Teisberg admits, "this next-generation UAV will still be far cheaper and easier to operate than crewed airborne systems are."
Teisberg's full write-up on the project, which could be deployed at-scale in the Antarctic and Greenland within three years, is available on IEEE Spectrum.
Main article image courtesy Eliza Dawson/IEEE Spectrum.
