逆合成孔径雷达(ISAR)具备二维高分辨成像能力,可实现对空间目标的高精度探测和监视。相比于地基ISAR,天基ISAR 能够对空间目标进行更灵活、更大范围的探测成像,为实现空间态势感知提供有利支撑。去斜接收回波体制可以大幅降低采样率,减轻系统硬件负担,现有ISAR 系统通常采用此种方式。然而在观测时间内空间目标相对于星载ISAR的相对斜距变化大,雷达需要不断改变录取波门以保证对空间高速目标的稳定跟踪,这严重破坏了雷达回波的相参性。同时,星载ISAR 相对空间目标的复杂运动几何导致运动补偿精度下降。针对空间目标ISAR 成像问题,文中提出了一种去斜回波相参性恢复方法,此方法可以逐脉冲处理回波,能有效恢复不同距离波门的回波相参性,并利用估计的参数对回波进行精确的运动补偿。基于此方法,设计了一种基于现场可编程逻辑门阵列的去斜接收相参性恢复快速实现方案。仿真实验验证了所提方法及其现场可编程逻辑门阵列实现方案的有效性。

Inverse synthetic aperture radar (ISAR) has two-dimensional high-resolution imaging capability and can achieve highprecision detection and monitoring of space targets. Compared with ground-based ISAR, space-borne ISAR can detect and image space targets in a larger range and is more flexible, which provides favorable support for space situational awareness. Dechirp receiving system can greatly reduce the sampling rate and lighten the hardware burden of the system; hence, this system is usually adopted by spaceborne ISAR. However, during the observation time, the range of the space target relative to the space-borne ISAR varies greatly, so the radar needs to constantly change the wave gate to ensure stable tracking of high-speed targets in space, which seriously undermines the coherence of radar echoes. At the same time, the decrease in the accuracy of motion compensation is brought about by the complex motion geometry of high-speed targets relative to space-borne ISAR. To solve this problem, a method for dechirp receiving coherence recovery of space-borne ISAR for space targets is proposed in this paper, which can effectively recover echo coherence with different range wave gates on a pulse-by-pulse basis, and the estimated parameters are used to accurately compensate for motion. Based on this method, a fast implementation scheme for dechirp receiving coherence recovery based on FPGA was designed. Simulation experiments verify the effectiveness of the proposed method and its FPGA implementation scheme.

TN957. 52;TN959. 74

国家自然科学基金青年基金资助项目(62301389); 平湖实验室开放基金资助项目;中央高校基本科研业务费资助项目(20103227364)