舰船目标逆合成孔径雷达成像分析

ISAR Imaging Analysis of Ship Target

对海上非平稳的舰船目标实现瞬时ISAR 2维成像。利用多普勒效应,得到目标的1维距离像,将各次回波包络对齐,在方位上进行自聚焦,即将目标等效为转台模型。在转台模型下,目标的运动分为平动和转动分量,平动分量在雷达成像过程中没有任何作用,因此需要将其补偿掉,这是雷达成像关键技术所在。对于运动比较平稳的观测目标,经过包络对齐和自聚焦后就可以直接得到其2维图像,但由于舰船目标通常是非合作目标,其目标特性和运动轨迹等很难确定,其回波具有明显的时变性,因此,按照多普勒中心的周期把成像时间划分为若干个时间段,针对不同的成像时间段得到相应时刻的瞬时ISAR像,由Matlab仿真对得出的分析结果进行了检验,表明该方法对于非平稳的舰船目标成像是有效的。

ISAR imaging has been the focus in recent years. Based on Doppler, the one -dimensional imaging is obtained. Through range alignment and auto - focus, the target can be rotation model, the movement of the ship target will be divided into a nent. The first one is useless in the ISAR imaging, so it must be corn equivalent to a rotation model. Based on the horizontal component and a moving compo- pensated. This is the important step. Based on the rotation model, for the moving smoothly ship, the two - dimensional ISAR imaging can be got through range alignment and auto -focus. But the apriori knowledge of uncooperative moving, the echoes have an obvious time - ship target motion is generally unknown, because of their variant character. Based on the periodicity of Doppler frequency, the whole dwell time is divided into several intervals, then, based on the above, the instantaneous ISAR imaging of every time interval can be got and simulations are done to verify the method. The verification result shows that the method is effective for the non - stationary ship imaging.