GNSS reflectometry for Earth's surface monitoring exploiting an open-loop approach

In the framework of the regional Italian project SMAT-F1, an experimental campaign using small aircraft flying an area above Vercelli (Piedmont, North Italy) was performed to remotely sense rice fields’ flooding state by applying Global Navigation Satellites System Reflectometry (GNSS-R) technique. Both direct and reflected GPS signals (the latest exploiting a bistatic configuration) where collected by the receivers mounted on the aircraft. The reflected signal was processed using Delay Doppler Maps and Delay Waveforms (DM) to evaluate Signal to Noise Ratio (SNR) in order to investigate the correlation with soil moisture. Final results not only indicated high spatial correlation between powers measured considering two close specular tracks observed from two GPS satellites, but also shown great agreement between processed SNRs and the surface conditions, including flooding or not, fields or boundaries.