弹载SAR俯冲段斜视成像算法

Imaging Algorithm of Missile-Borne SAR in Diving and Squint Mode

弹载SAR在俯冲段具有较大的下降速度和加速度,这使得距离徙动校正(Range cell migration correction,RCMC)变得困难,并且由于导弹在攻击目标前需要有一定的转弯机动时间,弹载SAR还往往工作在斜视模式下,此时常规的SAR成像算法不再适用。本文提出了一种弹载SAR俯冲段斜视成像算法,该方法在建立弹载SAR回波信号模型的基础上,首先在距离频域-方位时间域校正距离走动的主要部分,然后结合级数反演思想,推导出SAR回波信号的二维频域表达式,在距离频域-方位多普勒域进行剩余的距离走动和距离弯曲的校正,最后完成二维脉冲压缩,得到聚焦的图像。运算量的定量分析和实验仿真的结果验证了该算法的可行性和有效性。

The diving acceleration, vertical speed of missile-borne synthetic aperture radar （SAR） cause a difficulty in range cell migration correction （RCMC）. And in order to guarantee a certain turning time before attacking the target, missile-borne SAR should work under the squint mode. Therefore, the general SAR imaging algorithms are not suitable for missile-borne SAR. An imaging algorithm of missile-borne SAR in diving and squint mode is proposed. On the basis of establishing target echo signal model, the main part of the range walk can be cor- rected in range frequency-azimuth time domain. The remaining RCMC in range frequency-azi- muth Doppler frequency domain using an analytical form of the signal 2-D spectrum is derived by the method of series reversion. After finishing the 2-D pulse compression, the focused tar- get image is obtained. The quantitative analysis of computation and simulation results demon- strate its feasibility and effectiveness.