Research On High Speed Platform SAR/InSAR System Design And Realtime Process

Synthetic aperture radar(SAR)observes ground scene targets by transmitting and receiving large time and wide band wide product signals,and performs pulse compression processing to obtain two-dimensional high-resolution radar images.Interferometric synthetic aperture radar(InSAR)is based on the synthetic aperture radar,through the main and auxiliary antenna observation of the same ground target image registration,filtering,unwrapping and other processing,so as to obtain high-precision digital elevation model(DEM).SAR/InSAR processing system is not limited by time and space,so it is widely used in military and civil fields,so all countries in the world are vigorously developing SAR/InSAR processing system.The processing flow of SAR/InSAR is complicated,and the amount of data increases with the improvement of resolution or DEM accuracy.The conventional processing system usually processes the whole SAR/InSAR Data in ten seconds or minutes,but the processing speed is far from meeting the real-time processing requirements in seconds or even milliseconds,which requires the SAR/InSAR processing system to have the ability of fast response and processing.In order to meet the requirements of real-time processing in practical application,this paper takes the new generation field programmable gate array(FPGA)chip ku040 of Xilinx as the core interactive platform to realize the control of frontend radar system and the connection of back-end signal processing system,so as to complete the design of SAR/InSAR real-time signal processing system.The main contents and innovations of this paper are as follows1.The realization of SAR/InSAR real-time signal processing system for high-speed moving platform is studied.In order to solve the problem of real-time control and response of signal processing system,improve the speed of data transmission and meet the requirements of real-time processing,considering the existing modular,cross platform hardware devices and their rich peripheral interfaces,this paper puts forward the scheme of taking the high-speed serial port of PCI as the main control interface,So as to realize the real-time transmission of data and the realtime response control of the processing system.In order to solve the problem that the data transmission frequency of RS-422(electrical characteristics of balanced voltage digital interface circuit)is hundreds of times lower than the processing frequency of FPGA chip,which leads to the difficulty of data analysis,and in order to prevent the detection error caused by the non strict alignment of timing between different interfaces,this paper proposes to detect the data without distortion in the form of high-frequency sampling and low-frequency level.In order to solve the problem of different RS-422 serial port data timing disorder caused by the difference between inertial navigation and servo platform,before the data is sent to the center board for analysis by the PCI,the priority of data is classified,and the data is buffered according to the priority of data,and the serial data is sent to the PCI serial port by time division multiplexing,So as to realize the stable transmission of cross platform hardware device data.2.Based on FPGA + digital signal processor(DSP)+ central board hardware platform,a real-time SAR / InSAR processing system is designed and implemented,which integrates real-time control and processing.According to the advantages of high performance,high capacity and high integration of FPGA chip,this paper uses high-frequency clock source as processing clock to improve processing speed,and plans timing to improve processing efficiency.In order to solve the problems of data transmission,integration,distribution and analysis in cross clock domain,this paper proposes to implement bit width conversion,cross clock domain conversion and timing constraint integration in the form of cascaded first in first out queue(FIFO),so as to realize the accurate flow of data between different systems.In view of the complexity of SAR/InSAR processing system interaction,through the processing,regularization,reuse of interface timing and reasonable allocation of system control tasks,at the same time,using the advantage of FPGA parallel processing,the multi task,collaborative and efficient processing of the processing system is realized.For the processing of if data in FPGA,the pipeline is used to design the modules of if data analog to digital(AD)sampling,digital down converter(DDC),pulse compression and data integration and distribution in FPGA.The functions of data preprocessing in FPGA are realized.3.The real-time processing system of SAR/InSAR on high-speed motion platform is completed and verified by actual hardware test.After the design of the whole processing system,through the sub module test,RS-422 interface self loopback test,high-speed serial port function simulation and hardware test,the independent function test of the system is completed,and on this basis,the series joint debugging of the whole system is completed to realize the stable and high-speed operation of the system function.The effectiveness of the system is verified by the measured data.