Experimental Evaluation of GNSS-Based Frequency Synchronization for SAR Applications

Abstract

Phase synchronization is a crucial requirement for bistatic and multistatic SAR missions. One possible solution for this problem could be to use the same master oscillator for the radar payload and the GNSS receiver, which could allow the recovery of the oscillator phase noise from the carrier phase measurements. This solution would be cost-effective and straightforward, but its effectiveness depends on whether the GNSS receiver would maintain the spectral purity of the master oscillator internally. We executed zero and short baseline experiments to evaluate this technique with a commercial receiver. Despite some unexpected signatures on the carrier phase single-difference measurements, we achieved frequency synchronization of less than 10 ppm and phase synchronization of less than one degree at the L1 carrier frequency after applying a moving average filter of one second at a 10 Hz sampling rate. The results suggest the feasibility of the GNSS-based phase synchronization concept, but further experiments are necessary to evaluate it thoroughly.