Implementation Of Airborne SAR Imaging/GMTI Algorithm Based On Standard VPX

Synthetic Aperture Radar(SAR)not only enables high-resolution imaging of ground scenes at long distances but also detecting ground moving targets,and has great application value in military and civilian fields.SAR signal processing echo data is large,computationally complex,and has high performance requirements for processing systems.How to implement multi-mode and high-performance SAR signal processing on drone platforms has become a hot spot.In response to the strong demand for high-performance,low-power computing of unmanned airborne SAR signal processing systems,TI's TMS320C6678 chip based on Keystone architecture is designed to meet the requirements.It integrates 8 processor cores in a DSP chip,each core has a maximum frequency of 1.25 GHz.It is the most powerful DSP with floating point computing capability,and it also has rich interface resources.Based on the standard VPX bus and C6678 processor design signal processing board,it can meet the requirements of large data volume,large computing capacity and high bandwidth transmission in SAR real-time signal processing.This paper firstly outlines the airborne SAR working motion model,SAR imaging principle and basic Range-Doppler(RD)imaging algorithm,and then introduces the basic principles of clutter suppression and target detection in GMTI processing.In terms of implementation,this paper develops embedded real-time processing software for UAV-based SAR system based on TMS320C6678,and designs a data storage method suitable for multi-core parallel computing and a method for transposing the original address matrix of large data blocks.According to the characteristics of the unmanned aircraft platform and the measured data,an improved RD imaging algorithm combining motion compensation and two azimuth frequency estimation is presented.Finally,the software design scheme and SAR imaging,GMTI moving target detection,DBS imaging processing flow and multi-core parallel implementation methods of each module are given.Combined with radar real-time data,the real-time processing results of DSP and MATLAB processing results are compared to complete the transplantation and debugging of the algorithm.Aiming at the problem that TI lacks the support of the underlying library function,an efficient programming optimization method based on inline function is presented.It is verified that the computation time is greatly reduced and the execution efficiency of the program is effectively improved.After the external field flying test,the functions of each algorithm implemented by the DSP signal processing software are tested,the dual-polarized SAR images with clear resolutions of 3m,1m,0.5m and 0.3m,moving target track information and DBS images are obtained.The image resolution,processing time and other indicators are in line with the requirements,and satisfactory results are obtained to verify the feasibility of the design.Obtained dual-polarized SAR images,moving target points and DBS images with clear resolutions of 3m,1m,0.5m,and 0.3m.