DBS Doppler centroid estimation based on mutual information maximization

Doppler centroid is an important parameter of Doppler beam sharpening (DBS) imaging. By taking use of the principle that the adjoining beams contain the echo signals coming from the same imaging scene, which can be measured by image similarity, and based on the inherent relationship between image similarity and Doppler centroid, a maximum-mutual information Doppler estimation (MMIDE) is proposed. MMIDE puts the mutual information (MI) as the image similarity measure, and is optimized by application of an improved global threshold method and hierarchical approach. The algorithm breaks the conventional algorithms´ assumption that the azimuth spectrum of echo signal has the shape of round trip azimuth antenna pattern near Doppler centroid. The proposed method has high estimation precision in the case of uniform and non-uniform scene. Simulation results prove the effectiveness of the proposed algorithm.