GNSS-R measurement campaign: processing and analysis of reflected signals

The development of remote sensing techniques and methods, such as GNSS Reflectometry (GNSS-R), has become a prominent technology in various applications and topics of interest today. GNSS-R is a bistatic radar application that implements remote sensing for Earth observation. This technique is pivotal in determining environmental and geophysical properties of the Earth’s water and ground surfaces, including ocean wind speeds, surface material permittivity, and water content. Several significant satellite missions, such as TechDemoSat-1 (TDS-1) by SSTL, NASA’s Cyclone Global Navigation Satellite System (CYGNSS), and the European Space Agency’s FSSCat, have been launched to pioneer and explore this technology from space. The GNSS Reflectometry & Occultation eXperiment Field Test Campaign (GNSS-ROX FTC) constitutes a series of ground- and air-based field test campaigns conducted in the context of developing a GNSS-R payload for the Seamless Radio Access networks for Internet of Space (SeRANIS) satellite mission. The inaugural field test (GNSS-ROX FTC 1) was carried out using an airborne hexa-copter drone to confirm hardware setup and demonstrate proof of concept. The subsequent field test (GNSS-ROX FTC 2) involved a ground-based GNSS-R measurement from a high-altitude vantage point overlooking two water bodies—Lake Walchen and Lake Kochel. Notable GPS signal reflections for both Left Hand Circularly Polarized (LHCP) and Right Hand Circularly Polarized (RHCP) were observed at the recording antenna at certain points. The objective of these measurements was to receive, geolocalize reflection points, and conduct a thorough analysis. The paper discusses the development of the second field test and analyzes the findings and methods of precise reflection point geopositioning, considering the realistic and challenging settings of the Earth’s surfaces.