Abstract:

The dechirped echo and the Doppler echo of the boost phase ballistic target are approximately composed of multi-component linear frequency modulation (LFM) signals, due to its high radial velocity and approximate uniformly accelerate rotation. Therefore, inverse synthetic aperture radar (ISAR) images of the boost phase ballistic target will be defocused in both the range and cross-range dimensions, when the range-Doppler (RD) method based on discrete Fourier transform (DFT) is used in the imaging process. Fractional Fourier transform (FRFT) is used instead of DFT in both the range and azimuth compression, then the focused range profile and Doppler profile are obtained in the most concentrated energy fractional Fourier domain and the image is refocused. The simulation echo data from GRECO software are processed using the new method to verify its effectiveness.