Research On Airborne High-resolution SAR/InSAR Signal Processing Method And Real-time Processing

Synthetic Aperture Radar(SAR)is a remote sensing device that can achieve twodimensional high-resolution imaging.With the help of an airborne or spaceborne motion platform,it transmits a chirp signal with a large time-width-bandwidth product,and performs two-dimensional signal processing after receiving the echo to obtain two-dimensional highresolution scene information.Interferometric Synthetic Aperture Radar(InSAR)is developed on the basis of SAR.By adding an antenna,the carrier platform can use two antennas to illuminate the same scene during a flight.The difference in the positions of the two antennas leads to different time delays for receiving echoes,and combined with the measurement geometric relationship,the three-dimensional information of the illuminated scene can be obtained.SAR/InSAR technology plays an important role in many fields such as remote sensing mapping and geological exploration.In application fields such as remote sensing detection and battlefield reconnaissance,it is necessary to use SAR/InSAR technology to quickly obtain 2D/3D information of the illuminated scene,which puts forward requirements for the real-time performance of the high-resolution SAR/InSAR algorithm.The motion state of the airborne SAR/InSAR platform is unstable,and the high-resolution SAR/InSAR algorithm is difficult to process.Therefore,when the high-resolution SAR/InSAR algorithm is transplanted to the hardware system to realize real-time processing,targeted optimization is required to ensure its effectiveness.This article is based on the multi-core DSP TMS320C6678 chip,which realizes real-time processing of high-resolution SAR/InSAR algorithm.The main research content of this article can be summarized as follows:1.Research on high-resolution SAR/InSAR algorithm.This paper studies a high-resolution SAR imaging algorithm suitable for multiple working modes.Based on the echo signal,the processing steps of the imaging algorithm in the range and azimuth are analyzed in detail,and finally a high-resolution SAR image is obtained.The principle of InSAR altimetry is introduced,the InSAR processing flow is analyzed for high resolution requirements,and the key steps in InSAR processing are introduced in detail.The reliability of the high-resolution SAR/InSAR algorithm is verified using the airborne measured data.2.Designed and realized the data communication mode of the high-resolution SAR/InSAR real-time signal processing system.The hardware composition of the real-time signal processing system and the hardware architecture and working advantages of the core processor TMS320C6678 DSP of the signal processing subsystem are introduced.Aiming at the composition of the real-time signal processing system,the specific work content of each subsystem and the realization of real-time processing of the high-resolution of SAR/InSAR algorithm are designed.In order to realize the flexible transmission of data between the various subsystems in the real-time signal processing system,a star topology using the CPS1848 data exchange chip to construct the data communication of the real-time signal processing system is proposed.Realize the data communication mode between the signal processing subsystem,the signal processing subsystem and the data exchange subsystem,the signal processing subsystem and the signal acquisition subsystem.3.Realize high-resolution SAR/InSAR real-time signal processing based on multi-core DSP C6678.In view of the large gap between the range and azimuth data read and write speeds in real-time signal processing,based on the addressing mechanism of DDR3,combined with the data flow working mode of DSP,a method of data block processing is proposed.This block processing method can balance the reading and writing speed of the two-dimensional data in the multi-core DSP C6678 in the range and azimuth directions,and improve the work efficiency of the multi-core DSP C6678.The real-time processing flow of implementing high-resolution SAR/InSAR algorithm in the multi-core DSP C6678 is introduced in detail.According to the working characteristics of the multi-core DSP C6678,the important steps in the interferometric processing are improved and optimized.Meanwhile,the real-time performance and effectiveness of the high-resolution SAR/InSAR algorithm are verified using the airborne measured data.