Ambiguity-free Doppler centroid estimation technique for airborne SAR using the radon transform

In synthetic aperture radar (SAR) signal processing, the Doppler centroid estimation technique, called the "clutter-lock," is important because it is related to the signal-to-noise ratio, geometric distortion, and radiometric error of the final SAR image. Conventional algorithms have either ambiguity problems or somewhat high computational load. Using the fact that the Doppler centroid and the squint angle are directly related, we propose an ambiguity-free Doppler centroid estimation technique using Radon transform, named geometry-based Doppler estimator. The proposed algorithm is computationally efficient and shows good performance of estimating the absolute Doppler centroid.