机载逆合成孔径雷达(ISAR)成像是在远距离、全天时、全天候条件下对动态船舶进行微波成像和目标分类的关键技术。长时间累积可以带来更好的ISAR图像信噪比和信杂比,但船舶的摇摆等未知运动会显著影响长时间聚焦效果。对此,提出一种结合船舶运动参数估计与子孔径搜索的船舶成像实时处理方法。在平动补偿的基础上,根据船舶多普勒展宽、中心线斜率的变化曲线和散射点时频曲线估计船舶的旋转运动参数,实时提取最佳成像孔径,结合参数估计进行极坐标格式化和转动补偿,获取清晰的船舶图像。在不同实测数据集上进行对比验证,结果表明,相较传统成像方法,本文方法可以有效提升长周期聚焦处理的效果,实时获取高分辨率的ISAR船舶图像。
Airborne inverse synthetic aperture radar (ISAR) imaging is a key technology for microwave imaging and classification of dynamic ships in long-range, all-day, all-weather conditions. Long-time accumulation can bring better signal-to-noise ratio and signal-to-noise ratio of ISAR images, but unknown motions such as ship's sway can significantly affect the long-time focusing effect. In response, this paper proposes a real-time processing method for ship imaging that combines ship motion parameter estimation and sub-aperture search. Based on the translation compensation, the rotational motion parameters of the ship are estimated based on the variation curves of the ship's Doppler spread, centerline slope and scattering point time-frequency curves, the optimal imaging aperture is extracted in real time, and the polar coordinate formatting and rotation compensation are combined with the parameter estimation to obtain clear images of the ship. The results show that compared with traditional imaging methods, this method can effectively improve the effect of long-period focus processing and acquire high-resolution ISAR ship images in real time.
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