A novel Doppler ambiguity resolver based on contrast maximization

Doppler ambiguity number (DAN) is an important parameter in synthetic aperture radar (SAR) imaging. Erroneous DAN will affect the image quality with lower image signal-to-noise ratio (SNR) and degradation in the system impulse response function. In this paper, a novel Doppler ambiguity resolver based on contrast maximization is proposed. The new algorithm employs candidate DANs to make linear range cell migration correction (RCMC) to the range-compressed data, and check the quality of SAR image obtained by azimuth compression. The estimation value which meets the requirement of maximizing the image contrast will be treated as the final estimation result. Comparing with conventional methods, the new estimator has high precision in the case of both low and high scene contrasts. Experiments with RADARSAT-1 real data are carried out to demonstrate the performance of the proposed approach.