Unified GNSS-R formulation including coherent and incoherent scattering components

Abstract

Global Navigation Satellite Systems Reflectometry (GNSSR) is a sort of multi-static radar using navigation signals as signals of opportunity. Due to the large number of transmitting satellites multiple scattering points over the Earth's surface can be simultaneously tracked, which provides wide-swath and improved spatio-temporal sampling over current space-borne radar altimetry missions. The lack of experimental datasets from space covering signals from multiple constellations (GPS, GLONASS, Galileo and Beidou) at dual-band (L1 and L2), and dual-polarization (Right and Left Hand Circular Polarization: RHCP and LHCP), over the ocean, land, and cryosphere remains a bottleneck to further develop these techniques. 3Cat-2 is a 6 unit (3 × 2 elementary blocks of 10 × 10 × 10 cm3) cubesat mission designed and implemented at the Universitat Politecnica de Catalunya-BarcelonaTech. It will be launched in late July 2016. During one of the two stratospheric balloon flights of the 3Cat-2 payload, the P(Y) and C/A ReflectOmeter (PYCARO), it was found that the received signal power was nearly constant with the balloon height. This revealed the presence of a strong coherent component. This work presents the derivation of a unified equation to account for both incoherent and coherent scattering contributions.