Drone-mounted UWB snow radar: technical improvements and field results

Abstract

Drone borne radar systems have seen considerable advances over recent years, and the application of drone-mounted continuous wave (CW) radars for remote sensing of snow properties has great potential. Regardless, major challenges remain in antenna design for which both low weight and small size combined with high gain and bandwidth are important design parameters. Additional limiting factors for CW radars include range ambiguities and antenna isolation. To solve these problems, we have developed an ultra-wideband snow sounder (UWiBaSS), specifically designed for drone-mounted measurements of snow properties. In this paper, we present the next iteration of this prototype radar system, including a novel antenna configuration and useful processing techniques for drone borne radar. Finally, we present results from a field campaign on Svalbard aimed to measure snow depth distribution. This radar system is capable of measuring snow depth with a correlation coefficient of 0.97 compared to in situ depth probing.

Measurement of Snow Water Equivalent Using Drone-Mounted Ultra-Wide-Band Radar

“…We assume that the radar image is already preprocessed with both matched filtering and frequency-domain noise filtering. These basic preprocessing steps for the UWB radar data are described in more detail in [25,26].…”

“…Prior to migration, the sectioned data segment is expanded in fast-time according to the distance measured from the UAV to the snow surface. This method is explained in more detail in [26].…”

“…The ultra-wideband snow sounder (UWiBaSS) is a custom-developed radar system for drone-mounted snow measurements. Papers [25,26,43] detail recent advances of the radar system. New developments include retrofitting the radio frequency (RF) operation band as well as digital modules with 3D printed casings coated in conductive paint to reduce weight while still offering electromagnetic interference (EMI) protection.…”

“…The basic preprocessing steps for the sampled radar data involve match filtering to correlate the received signal with the transmitted signal, high-pass filtering to remove low-frequency cross-talk between receiving (RX) and transmitting (TX) antennas, reference subtraction, and altitude correction involving rectification of the snow surface return. A detailed description can be found in [26].…”

“…For this data set, the returning signal from the snowpack was taken at the second period of the transmitted signal owing to the radar system having a 5.9-m unambiguous range, and the data collection was taken from approximately 7-m relative altitude, excluding snow depth. For more information on performing measurements outside the unambiguous range from UAV radar, see [26].…”