星载ScanSAR成像处理技术研究

An Imaging Processing Technology for Satellite-Borne ScanSAR

由于天线在不同的子带进行扫描,星载扫描模式不能像条带模式那样,获得连续的方位向相位历史,利用条带模式高精度处理算法(如距离-多普勒算法)处理ScanSAR数据,通过在脉冲扫描间隔中填零,把扫描数据看成中间填零的相干脉冲串序列,等效成条带SAR数据,利用条带模式的处理算法进行成像。针对填零后的数据,数据量大,可以采用基于通用图形处理单元的并行处理技术,加快处理速度。对填零处理形成的栅瓣调制,通过滤波进行消除。这样处理的图像和条带模式的图像具有相同的辐射和几何分布特性,有效抑制扇贝效应带来的影响。对实测星载ScanSAR数据进行成像处理,试验结果表明该方法的有效性。

Due to its specific way of scanning over multiple sub-swaths of a radar image, a ScanSAR （scanning synthetic aperture radar） cannot sample Doppler histories continuously like a regular SAR in strip- map mode. Imaging processing method by standard high precision algorithm（e, g. range-Doppler） is intro- duced. Long burst trains with zeroes inserted into the inter-burst intervals can be processed coherently. The paralleled processing method based the general purpose graphic processing units（GPGPU） is used to acceler- ate the processing speed of mass raw data. Because of the interference of the burst images, the impulse re- sponse shows a periodic modulation that can be eliminated by a subsequent low-pass filtering of the image. The image is automatically consistent with regular SAR mode image with respect to both geometry and radi- ometry. Scalloping effect is well suppressed. The ENVISAT/ASAR SCAN model experimental data-set pro- cessing results show the effectiveness of the method.