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From the beginning of the 1990s, the use of Global Navigation Satellite System (GNSS) reflected signals have been identified as a as source of opportunity for remote sensing applications. In the last two decades, the potential of the technique have been demonstrated for ocean and continental surfaces studies, and several applications have been proposed in the context of high availability of GNSS signals. The GNSS-R technique is generally based on the use of a passive receiver simultaneously acquiring the direct and reflected signals from various GNSS satellites to estimate geophysical parameters from the scattering surface. In the last years, several ground-based [2], [3], airborne [4] and space-borne [5]–[8] experiments have been proposed. The most considered application foreseen for GNSS-R is ocean altimetry for a precise determination of sea-surface heights as well as roughness and wind direction. For continental surfaces, because of direct relationship between surface permittivity and reflected signal, different approaches [6], [9], [10] have been proposed to estimate surface parameters (soil moisture, vegetation biomass, snow). Different observables have been proposed to analyze GNSS signals: the Delay-Doppler Map, the direct and reflected complex waveforms bistatic signal, the ratio between the direct and reflected waveform’s peak time series (Interferometric Complex Field). In this context, the airborne instrument GLORI is proposed to demonstrate contribution of GNSS-R to estimate soil moisture over agricultural soils and biomass of forests or annual cultures. A secondary goal is the feasibility of centimeter-precision altimetry above continental water bodies. The second section describes the characteristics of GLORI instrument. The third section presents airborne campaigns realized over the south West of France and fourth sections discusses the first results. Conclusions are gathered in section 5.
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