A COMPARATIVE STUDY OF THREE METHODS USED INGLOBAL NAVIGATION SATELLITE SYSTEMREFLECTOMETRY (GNSS-R) FOR SPECULAR POINTCALCULATION APPLIED TO SIGNALS OF OPPORTUNITYP-BAND INVESTIGATION (SNOOPI)

In Global Navigation Satellite Systems Reflectometry (GNSS-R) a critical theme is in un-
derstanding and delving into determining specular points, and how to optimize its solutions.
The implications are significant for soil moisture, Snow Water Equivalent (SWE), water stor-
age, and climate dynamics. For instance, the Signals of Opportunity in P-Band Investigation
(SNOOPI) will utilize observations in reference to the specular point to evaluate measurements
that could be used to determine water content, soil moisture, and SWE. The focus of this
study is presenting and evaluating two prominent methods for determining specular points:
the Minimum Path Delay (MPL) and the Unit Difference (UD). Specular point determin-
nation presents various challenges which include: surface roughness, temporal and spatial
variability, and multipath effects. All of these earth’s surface characteristics pose a challenge
for scientists and engineers who wish to collect terrestrial parameters. The analysis in this
study offers a comparative approach focusing on data from the simulator for the CubeSat
SNOOPI mission is to evaluate specular point determination accuracy as well as offer a real-
world application to determine the efficacy of the two methods. Through this evaluation,
the researcher aims to improve specular point determination techniques used in the GNSS-R
community and offer insights into future techniques and how they can support each other
for more precise results.