Temporal Decorrelation of Scattered GNSS Signals

The Global Navigation Satellite System Reflectometry (GNSS-R) is an emerging remote sensing technique based on the exploitation of scattered navigation signals for monitoring bio-geophysical parameters of the Earth surface. The receiver is placed onboard of airborne or spaceborne platforms, whose movement can affect the feature of the gathered signals. These can present strong fluctuations, which depend on the electromagnetic parameters of the illuminated surface and on its statistical features. Fluctuations have been studied from decades by the radar community, especially to understand the decorrelation of the scattering in radar interferometry. It has been done, however, by only considering uncorrelated point-like scatterers, leading to a simple model. To characterize the temporal decorrelation of the near-specular scattering in GNSS-R systems, we describe here some numerical results collected by a moving receiver changing the random surface parameters and accounting for the coherent/incoherent nature of the scattered field.