GNSS-Based Phase Synchronization for Bistatic and Multistatic Synthetic Aperture Radar

The feasibility of single-pass interferometric or multistatic synthetic aperture radar (SAR) mission concepts largely relies on the ability to achieve the matching of the carrier phase of the different radar instruments of the constellations within a few degrees. We put forward a phase synchronization scheme in which the global navigation satellite system (GNSS) receiver and the radar payload share the same oscillator; the estimation of the synchronization phase follows from the combined evaluation of the navigation raw data and the precise orbit and baseline determination solutions. The article presents a discussion on accuracy, an error analysis, and an evaluation of its viability using a system-oriented simulation of the navigation data. The results suggest the proposed approach is capable of delivering reliable estimates of carrier frequency and phase errors for low- and medium-frequency systems in the absence of strong baseline velocity deviations if multipath and other systematic errors are successfully suppressed or calibrated.