Fractional Fourier Transform for Moving Target Detection and Location in Spaceborne SAR

Doppler parameter estimation of Azimuth echo is the key for Synthetic Aperture Radar (SAR) ground moving target detection. This paper will apply Fractional Fourier Transform (FrFT) to moving target echo signals for Doppler parameter estimation in Spaceborne SAR. It's well known that within a synthetic aperture time, the relative motion between moving targets and SAR makes the slant range vary with time so that Doppler parameters will change accordingly. Compute the mean values of the gained Doppler centroid and frequency modulation rate along azimuth direction for each target, and this ensures that echoes of a moving target may be approximated by a linear frequency modulation (LFM) signal in theory. Simulation results prove that the parameter mean values can make imaging quality of moving targets better and achieve accurate real time processing within a synthetic aperture time.