A new method for Doppler centroid estimation for spaceborne SAR based on chirp scaling algorithm

摘要

We introduce a new method to estimate the Doppler centroid accurately based on chirp scaling algorithm after investigating the performances of curvature factor Cs and the effective FM rate Ks regarding to Doppler ambiguity number (DAN) and finding that Cs and Ks will lose their functions if a wrong DAN is used and the generated image definition will be degraded. So relations between definition evaluation functions (such as entropy and variance) and the DAN can be used to find the correct DAN which makes the entropy minimum or the variance maximum. Radarsat raw data is used to test the proposed method and find that the performance of using variance is better than that of using entropy.