Real-time estimates of differential signal phase for spaceborne systems using FPGAs

The high cost and inaccessibility of spaceborne systems necessitates the adaptation of computing resources based on changes in environmental conditions. In this paper, a new, adaptive phase difference detection circuit that can be implemented in reconfigurable hardware is described. This circuit measures both phase changes of a single signal over time and phase drifts between two associated signals. This information can be used for anomaly detection for a variety of spaceborne applications, eliminating the need to transmit data for further terrestrial processing. We demonstrate the benefit of this adaptive circuit using a new state-of-the-art data acquisition system developed for the NASA Surface Water Ocean Topography (SWOT) project. Phase calculations with an error of less than 2% are determined using our adaptive approach.