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由于逆合成孔径激光雷达(ISAL)发射信号具有超短波长、超大带宽的特点,在对匀速运动目标成像时,其回波信号存在色散效应,且目标散射点容易产生越距离单元徙动,利用传统的距离-多普勒成像算法将无法获取理想的ISAL图像。在对匀速运动目标回波精确建模的基础上,深入分析了由于目标运动引入的距离色散。提出利用分数阶Fourier变换(FRFT)补偿距离像色散,并对距离压缩后的回波信号进行预相干化处理,之后结合keystone变换消除目标散射点存在的越距离单元徙动,并最终实现对目标的高分辨成像。仿真实验验证了成像算法的有效性。
Due to the ultrashort wavelength and large bandwidth of the transmitted signal of inverse synthetic aperture laser radar (ISAL), the echo signal has the dispersion effect when imaging the uniform moving target, and the target scattering point tends to generate more distance cell migration. By using the traditional Distance - Doppler imaging algorithms will not be able to obtain the ideal ISAL image. Based on the accurate modeling of uniform moving target echo, the distance dispersion introduced by the target motion is deeply analyzed. Proposed the use of fractional Fourier transform (FRFT) to compensate the distance image chromatic dispersion, and the distance compressed echo signal pre-coherent processing, combined with the keystone transform to eliminate the existence of the target scattering point of the distance cell migration, and ultimately achieve the target High resolution imaging. Simulation experiments verify the effectiveness of the imaging algorithm.