基于FPGA的微型SAR成像信号处理技术

微型SAR(MiniSAR)成像处理系统通过现场可编程门阵列(Field Programmable Gate Array, FPGA)设计并实现。该系统中成像处理流程以极坐标格式算法(Polar Format Algorithm, PFA)为基础，首先对回波数据进行参考距离补偿，再采用尺度变换原理(Principle of Chirp Scaling, PCS)代替插值过程实现距离向的重采样，能够在提升算法精度的同时，提高运算效率；方位向处理采用高精度的Sinc插值方法，流水线输出插值结果，运算效率进一步提高；最后，系统通过相位梯度自聚焦(Phase Gradient Autofocus，PGA)算法实现残留相位误差的估计和补偿。基于Xilinx公司的Virtex7-XC7VX6907开发板对系统进行了成像处理和验证，系统工作频率为200MHz，在5.10s时间内实现8192×4096个采样点的32位单精度浮点成像处理。实测数据处理结果验证了系统的有效性。

MiniSAR Imaging Processing Technique Based on FPGA

A miniaturized synthetic aperture radar (MiniSAR) imaging system is designed and realized based on field programmable gate array (FPGA). The proposed system relies on the polar format algorithm (PFA) and compensates for the echo data using the reference distance. The principle of chirp scaling (PCS) is applied to replace the traditional interpolation to implement the range resampling, which improves the accuracy and the efficiency of the algorithm. Then, the high precision interpolation kernel via the Sinc function is employed to resample the azimuth signal. The interpolation results are pipeline output, which further enhances the system efficiency. Finally, the phase gradient autofocus (PGA) algorithm is used to estimate and compensate for the remained phase error accurately. Utilizing the Virtex7-XC7VX6907 evaluation board of the Xilinx Company with the clock frequency of 200MHz, the system takes 5.10s to realize the single-precision floating-point image with 8192×4096 pixels. The experimental data demonstrates the validity.