Design And Implementation Of High Resolution SAR/InSAR Real-time Signal Processing Communication System And Data Preprocessing

Synthetic aperture radar(SAR)is a kind of remote sensing equipment that can detect and image the target scene.It is different from optical imaging,which is limited by clouds,day and night.It can detect and image the target scene all day and all weather to obtain twodimensional high-resolution images.Interferometric synthetic aperture radar(InSAR)adds an antenna to SAR,it receives the signal echo respectively through two antennas during the flight of the high-speed moving platform,and then obtains two coherent SAR images.After image registration,filtering,phase unwrapping and other algorithms,a high-precision digital elevation model(DEM)is obtained.Based on SAR,2D measurement is extended to 3D measurement.Compared with other remote sensing equipment,SAR/InSAR processing system has its unique advantages,so it is widely used in military and civil fields.Therefore,SAR/InSAR technology has high research value,and SAR/InSAR real-time signal processing system is the focus.The implementation of SAR/InSAR algorithm is complex,and the amount of data and computation increases with the improvement of illumination scene and resolution and DEM accuracy.The processing time of conventional SAR/InSAR processing system often has dozens of seconds or minutes can not meet some application scenarios with high real-time requirements.Considering the demand of real-time processing,this paper completes the design of SAR/InSAR real-time signal processing system by taking the signal acquisition system and signal processing system as the core,plus some other auxiliary subsystems.Among them,the signal acquisition system is mainly composed of an AD9680BCPZ-1250 chip and an FPGA chip xcku040-ffva1156-2-i of Xilinx company as the core to complete the signal acquisition.According to the characteristics of SAR/InSAR imaging processing,some data preprocessing algorithms are implemented on FPGA.At the same time,because the whole real-time processing system has a large amount of data to communicate,an efficient and robust communication system is the basis of its normal and stable work.The main research contents and innovations of this paper are as follows:1.This paper deeply studies SAR/InSAR real-time signal processing system.Aiming at the storage problem of large amount of data during real-time processing,a storage system is added to solve this problem in the process of real-time imaging.This paper proposes to use the serial connection transceiver(RocketIO)as the main control interface between the signal acquisition subsystem and the data storage subsystem,so as to realize the real-time communication,cross clock domain transmission,bit width conversion and real-time response control,the data storage and playback module of the real-time system is designed and developed;At the same time,the system builds an upper computerd and uses the corresponding configuration command,and configures the playback module through RS-422 serial port to accommodate more scenes.2.Aiming at the problem that it is difficult to send InSAR imaging double-path data quickly after parallel processing,which affects the subsequent real-time processing,this paper proposes a data fast sending method based on finite state machine.The communication module of signal acquisition system and data storage system is developed by using single SRIO(Serial Rapid Input Output,SRIO)interface,which solves the problem that InSAR dual data is difficult to send quickly,so that InSAR dual data can quickly complete data packaging,response and transmission,and can be verified in the real-time processing system.3.After completing the dual real-time signal preprocessing of high-resolution InSAR main and auxiliary images for the problem of mismatch between InSAR dual channel ADchip four channel data acquisition and real-time processing clock,an InSAR dual high-speed data acquisition method is proposed to obtain high repetition frequency sampling data by parallel DDC processing after data acquisition through four channel ADchip low sampling frequency so as to solve the mismatch between sampling frequency and actual processing clock,Then,the distance pulse compression.Aiming at the problem that the actual imaging bandwidth is greater than the Doppler bandwidth required for imaging in the process of SAR/InSAR realtime signal processing,combined with the characteristics of the algorithm and FPGA pipeline processing method,the two steps of pre filtering and down sampling are organically combined to solve the problem of excessive azimuth data in the process of SAR/InSAR realtime processing,and realize the dual imaging processing of InSAR main and auxiliary images,The imaging efficiency of the system is improved.4.Test the preprocessing module and communication system of the real-time processing system.Joint debugging with the front end of the radar system enables the SAR/InSAR realtime signal processing system to work stably and efficiently.The effectiveness of SAR/InSAR real-time signal processing communication system and data preprocessing is verified by the actual hang flight experiment.