用频率变标算法处理大斜视角SAR数据

Large Squint SAR Data Processing Using Frequency Scaling Algorithm

给出了一种改进线频调变标算法 ,该算法适用于处理距离解线调后的聚束式SAR数据。应用频率变标技术 ,给出的算法在消除信号剩余视频相位项的同时进行距离单元徙动校正 (RCMC) ,避免了插值运算。对大斜视角数据 ,由于二次距离压缩误差的影响 ,偏离参考距离的散射点未能完全聚焦 ,且离参考距离越远聚焦性能越差。在一定的聚焦深度下 ,用不同的参考距离对数据进行二次距离压缩 ,并用相应的滤波器滤出聚焦部分图像 ,然后拼接成完整的距离像 ,从而有效地降低了距离压缩误差。仿真结果表明 ,对给定的SAR参数 ,在斜视角为 6 0°时 。

This paper presents an extended chirp scaling algorithm, named frequency scaling algorithm. This algorithm allows the processing of dechirped raw data. By means of a new frequency scaling operation, the range migration is corrected without interpolation, and the residual video phase term is removed at the same time. For large squint angle, the image will be defocused away from the reference range due to the secondary range compression (SRC). In the paper we use different reference ranges to do the SRC, and then filter out the well-focused signal to combine the whole range images. By this approach, the SRC error can be reduced effectively. Simulation result shows that good images can also be achieved when the squint angle is up to 60 degree.