Velocity estimation of moving target based on concatenated ATI and inverse radon transform in three-channel circular SAR

The echo signal of moving target in circular SAR is complicated, which results in the difficulty of velocity estimation of moving target. In this paper, a method based on concatenated ATI and Inverse Radon Transform (IRT) for velocity estimation of ground moving target in circular SAR is presented. The proposed method aims for small surveillance region with one single moving target in linear trace with constant velocity. The concatenated ATI method is exploited as follows: in first-level, two ATI signals are calculated between two adjacent channels. The phase of first-level ATI signal is the superposition of a sinusoid signal and a linear signal. With exploitation of ATI method of the two first-level ATI signals, second-level ATI signal is obtained, which can be seen as a sinusoid frequency modulation signal. In this case, we map the time-frequency image of the second-level ATI signal to parameter space with IRT, and velocity parameters can be estimated by extracting positions of peaks in the parameter space. Simulation results are illustrated to demonstrate the effectiveness of the proposed method.