Pretreatment And High-resolution Real-time Imaging Of Sar Real-time Signal Processing Systems

The real time processing of the SAR signal can be divided into three relative independent stages. They are preprocessing, imaging formatting and image post-processing. The goals of the pre-processing is trying to eliminate the data errors as much as possible, including motion error, system error and so on. Therefore, the signals after preprocessing will be improved to near its ideal mathematic model. Real time SAR signal preprocessing occurs on the radar raw data, and have no direct relationship with the imaging algorithm. Its content is wide. This thesis discusses the real time SAR preprocessing theory and its realization mainly from the aspects as SAR automatic gain control(AGC), the adaptive rectification the balance of the quadratic channels, the fixed sub-sampling azimuth FIR filter, the adaptive sub-sampling azimuth filter and the IMU motion compensation. It also discusses the antenna beam control, the radar pulse control, and the clutter-lock on the raw data stage, etc. The conception of adaptive filtering is applied to most of the signal processing stage above. With the SAR signal processing developing to the direction of high resolution and real-time processing, it has become a critical factor that providing high quality raw signal to image formatting stage. Therefore, SAR signal preprocessing becomes more and more important. With the development of VLSI, high density memory with high speed, and computer technology, it is not very difficult to develop a full digital airborne SAR real-time signal processing system now. However, full digital, high-resolution real-time space-borne signal processing system is still a challenge. This thesis discusses the realization of real-time processors for space SAR from both the algorithm and the system architecture.