Ultra wide band synthetic aperture radar real time processing with a subaperture nonlinear chirp scaling algorithm

The low frequency ultra wide band (UWB) synthetic aperture radar (SAR) is famous for its wide integration angle, which lead to a large memory capacity requirement to several gigabytes. In this paper, the base parameters of the airborne UWB SAR real time processor are analyzed. Then a modified sub-aperture and sub-band nonlinear chirp scaling (NCS) algorithm is used to divide the SAR signal processing into pipelined parallel steps. To improve the image quality, motion compensation (MoCo) and radio frequency interference (RFI) suppression are introduced in real time processing. Using a distributed-memory structure, the design and implementation based on digital signal processors (DSPs) are proposed finally. The results of the flight experiment on a “Y12” airplane show that the demanded image quality can be obtained by using real time processing.