Comparison and synergy of BPSK and BOC modulations in GNSS reflectometry

Signals from global navigation satellite systems (GNSSs) have been advocated as opportunities for remote sensing of the Earth. In the multi-GNSS era, signals from different constellation, at different frequency, and under different modulation are available to facilitate such applications. Existing open service GNSS signals can be roughly categorized as either binary phase-shift keying (BPSK) modulation or binary offset carrier (BOC) modulation; it is desired to establish a unified data processing procedure to account for all these signals. This article proposes a framework to synergize BPSK and BOC signals for GNSS reflectometry (GNSS-R) applications by establishing a channel response function to model the scattering phenomena and a commutative diagram to illustrate the interrelationship among direct and reflected signals under different modulations. The results are verified by processing the flight test data of the GNSS-R receiver of the TRITON mission.