Prototyping a GNSS-Based Passive Radar for UAVs: An Instrument to Classify the Water Content Feature of Lands

Abstract

Global Navigation Satellite Systems (GNSS) broadcast signals for positioning and navigation, which can be also employed for remote sensing applications. Indeed, the satellites of any GNSS can be seen as synchronized sources of electromagnetic radiation, and specific processing of the signals reflected back from the ground can be used to estimate the geophysical properties of the Earth’s surface. Several experiments have successfully demonstrated GNSS-reflectometry (GNSS-R), whereas new applications are continuously emerging and are presently under development, either from static or dynamic platforms. GNSS-R can be implemented at a low cost, primarily if small devices are mounted on-board unmanned aerial vehicles (UAVs), which today can be equipped with several types of sensors for environmental monitoring. So far, many instruments for GNSS-R have followed the GNSS bistatic radar architecture and consisted of custom GNSS receivers, often requiring a personal computer and bulky systems to store large amounts of data. This paper presents the development of a GNSS-based sensor for UAVs and small manned aircraft, used to classify lands according to their soil water content. The paper provides details on the design of the major hardware and software components, as well as the description of the results obtained through field tests.

UAV-Based GNSS-R for Water Detection as a Support to Flood Monitoring Operations: A Feasibility Study

“…Many designs for airborne GNSS-R sensors have been presented in the literature. For example the sensor presented by Troglia Gamba et al [48] implements a SDR based GNSS-R on an ODROID-X2 microprocessor able of receiving both the left-hand circular polarized (LHCP) and the right-hand circular polarized (RHCP) reflected signals using two front-ends streams. Esterhuizen and Akos [49] also presented a miniaturized receiver based on two GPS L1 front ends and a Nano-ITX Single Board Computer (SBC) to store raw signal samples, which were analyzed in post-processing [50].…”

“…Estimate the performance of the GNSS-based passive radar developed by Troglia Gamba et al [48] in monitoring water surfaces on ground, when it is mounted on board a small UAV. This assessment could set-up a further source of geospatial data for the system developed in the I-REACT project [52].…”

Snow Depth Estimation with GNSS-R Dual Receiver Observation

“…Other satellite missions have also demonstrated the capabilities of GNSS-R, which includes UK-DMC (United Kingdom -Disaster Monitoring Constellation) and SMAP (Soil Moisture Active Passive) [5,6]. Over the past quarter century, the GNSS-R theoretical framework has been greatly enhanced and its application has been extended from marine remote sensing [7][8][9][10][11][12][13] to land remote sensing [14][15][16][17][18][19][20].…”

Passive Detection of Low-Altitude Signal Sources Using an Improved Cross-Correlation Algorithm

“…Passive radar can be used to detect signal sources by sensing the corresponding RF signals [10]. Linear fusion has been employed previously [11] for target recognition in a passive multistatic radar system, and bistatic range measurements have been used to find the position of a target [12].…”