Modified GNSS-PIR and Initial Verifications From the Perspective of Altimetry.

This paper proposed a modified structure of GNSS pseudo interferometric reflectometry (GNSS-PIR). The combination of the direct and reflected signals at the front end was modified as the combination of their coherent sums in the baseband, so that GNSS-PIR could be more conducive under the framework of conventional GNSS reflectometry. To verify its feasibility, two altimetry experiments were carried out, over land and water surfaces, respectively. Strong oscillations were observed in GNSS-PIR waveforms from both scenes. Altimetry results showed that GNSS-PIR achieved ∼5cm precision over land surface and ∼4cm precision over water surface. It indicated that GNSS-PIR was available for retrieving parameters related with reflector height, like water level, soil moisture, et al.