A Method of Moving Ship Imaging and Velocity Estimation with Airborne Sar

Abstract

This paper mainly studies the airborne SAR imaging of moving ship under low sea state, and proposes a method to estimate ship velocity and achieve focused imaging. Moving ships may cause range migration, Doppler frequency shift and chirp rate changes in slow-time dimension, which make image defocused. A refocusing method is proposed based on correlation Doppler estimator, Second Order Keystone Transform (SOKT) and integrated cubic phase function (ICPF) to deal with these problems. First, linear range walk and linear phase are compensated with correlation Doppler estimator. Then, range curvature and quadratic phase are eliminated with SOKT and ICPF, respectively. With these estimated parameters, we can solve the velocity of the ship and obtain the focused image. The processing results of simulation and real data both verify the algorithm.