This paper introduces an imaging algorithm with application of fractional Fourier transform (FrFT) for ground moving train imaging by Ku-band ground-based radar. In view of the fact that the train speed is varying when acrossing the radar beam, the multiple Doppler parameters are estimated corresponding to different range positions, i.e., they are estimated from different sections of data in FrFT domain, then the train is imaged section by section, and finally these sectional images are combined to get the full image of the train. Because traditional parameter estimation method by two-dimensionally searching the peaks in FrFT domain is inefficient, we transfer the parameter searching problem into an one-dimensional optimization problem, which can be solved with high efficiency by using the golden section searching method.
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