Implementation of the Kalman Filters for Estimating Time-Varying Doppler Centroids of SAR Systems

In this work, we propose that Kalman filtering (KF) may provide superior performance to estimate Doppler centroid frequencies of Synthetic Aperture Radars (SAR) systems. By measuring absolute Doppler frequencies or baseband wrapped Doppler frequencies, KF based on the polynomial model has the ability to smooth out observation noise and more importantly, to unwrap baseband Doppler centroids. In other words, KFs may be considered as superior mathematic tools for tracking Doppler frequencies. Numerical results using experiment data show their excellent performance of Doppler tracking. The proposed method in this work may be applied to practical SAR processors.