CLEAN and FrFT based Cross-range Scaling Method for ISAR Image

Improper scaling for ISAR image will result in shape and proportion distortion of the target, unfavorable to target detection and recognition. According to the system bandwidth, the range scaling factor is easily obtained. To determine the cross-range scaling factor, the rotational angle between the radar and target is needed. However, this is usually unknown, resulting in difficulty of cross-range scaling. In this paper, the CLEAN is employed to extract dominant scattering centers from the ISAR image. Then, the fractional Fourier transform (FrFT) is utilized to estimate the chirp rates of the range cells in which the dominant scattering centers locate. With the chirp rates estimation result, the cross-range scaling factor can be calculated, and cross-range scaling of the ISAR image is finally implemented. Simulation results demonstrate the effectiveness of the cross-range scaling method.