星载合成孔径雷达回波信号模拟源研究

A Spaceborne SAR Simulator

论述了星载合成孔径雷达(SAR)回波信号模拟源的一种实时实现方法和基于PCI总线与CPLD的硬件设计。主要针对点目标模型和椭圆轨道模型,首先模拟点目标的方位向相位历程和天线方位向增益数据。通过PCI总线实现数据实时传输,利用CPLD形成的延时信号,触发线性调频源产生距离向的线性调频信号,经过模拟源移相、加权,最终形成系统回波信号。试验结果表明该方法设计合理,软、硬件编程灵活,为系统的更新换代以及今后分布目标模拟源的设计提供了很好的技术支持。

This paper introduces a real-time spaceborne SAR simulator and the hardware design based on the PCI bus and CPLD chip. This simulator is mainly based on the parameters of the SAR and the satellite orbit. The foundations of the simulation method are the point target model, the ellipse orbit model, and the ellipse earth model. First, the simulation software can calculate both the phase-shifted data and the weighted data of the azimuth direction of antenna. These data can be synthesized and stored in one file. Second, these data are transferred to the time-controlled unit through PCI bus. Then, the LFM generates the linear frequency modulated signal, which is phase-shifted and weighted in the simulator, by means of the delay signal generated by CPLD timer. Finally, the system echo signal is formed. This signal can be used to verify the system characteristics, such as resolution, bandwidth, and the spectrum features etc.. After digitalization, the data are stored in the storage device in the PC. Based on the classical R-D algorithm, the compressed data can be achieved. The compression results in this paper show that this method is feasible, and that the flexibility of the software and the hardware of the simulator has advantages in the system update and the distributed target simulator design.