Fpga-based Sar Real-time Imaging Technology Research

Synthetic Aperture Radar (SAR) is a kind of high-resolution imaging Radar. Using SAR we can obtain high-resolution Radar images under all weather, day and night, and long distance conditions. With the system towards the large bandwidth, high-resolution, signal processing real-time direction, SAR raw signal has a high data rate, so a higher demand is raised to real-time imaging system. SAR imaging computing capacity mainly concentrated in the pulse compression in both range and azimuth directions. Often multi-chip high-speed DSPs are used to implement in parallel mode, and there are many engineering applications. But in recent years, with the development of programmable devices, the FPGAs become better than the DSPs in digital signal processing. Contrast to the DSPs , FPGAs has more hardware resources, and can be used to deal with faster and better flexibility.This thesis studys on the implementation of real-time RD algorithm based on FPGA from the point of the application of real-time SAR imaging system.The main job is as follows:1. According to the requirement of the system, the design is determined. A monolithic high-density FPGA is used to process the pulse compression of both the distance and azimuth directions, implement the control of corner turn memory(CTM), and a variety of interface protocol; Two high-speed DSPs are used to implement the Autofocus algorithm.2. According to the system design, the hardware design is implemented, including the circuit design and chip selections.3. The FPGA's development and debugging are implemented, including FFT, IFFT, CMUL and control of CTM. Based on this, Implementation of a high efficient corner turn memory arithmetic with writing and reading by row based on DDR SDRAM is introduced. When using CTM with this algorithm , the speed of reading and writing matches and meets the requirement of pipelined operation. Finally a method of model implementation for complex image based on CORDIC algorithm is introduced. The algorithm's hardware implementation structure is analysed, and implementation methodology and simulation results are given.4. System's debugging is implemented, the function of the system is verified, system's requirement is satisfied, and a number of pieces of real-time imaging is produced.