Research On Video SAR Motion Compensation Algorithm And Realization Of Imaging Software

Video Synthetic Aperture Radar(Video SAR)is a new SAR imaging system with rapid development in recent years.Video SAR can display the dynamic information of the observation area in the form of continuous image data through continuous monitoring of maneuvering targets in the scene.Its high frame rate and high resolution imaging ability realizes real-time imaging of objects in the scene.The key technologies of video SAR imaging include high frame rate,high precision imaging algorithms and motion compensation algorithm.Thesis conducts an in-depth exploration of the relevant technical principles in video SAR imaging process.The research content and main innovations of thesis can be divided into the following three aspects:1.In view of the high resolution and high frame rate imaging ability of video SAR,compared with traditional SAR,thesis analyzes the basic principles of high frame rate and high resolution imaging of video SAR,introduces the imaging of video SAR circular spotlight,compares a variety of SAR imaging algorithms,analyzes the sources of motion errors and explains the realization principle of phase gradient autofocus algorithm.Finally,the imaging results after different imaging algorithms and autofocus compensation are given.2.Based on the circular spotlight mode,the motion error model of Video SAR is established.In the actual imaging process,the radar platform often deviates from the ideal motion trajectory,causing the echo phase being affected by motion errors.Aiming at the motion error problem in the process of video SAR imaging,combined with the motion sensor error data,the phase error form is derived,propose the three-dimensional space phase decoupling of the error compensation scheme.By projecting the APC point under the real trajectory to the ground plane,the de-frequency modulation processing and resampling method are used to remove the height term,and then the height error is compensated,and the phase error is further simplified to one-dimensional space variant form.At the same time,on the basis of the simplified quadratic phase error,a self-focusing method based on sub-region division is proposed.By linear interpolation between adjacent phase correction vectors,the Spatially-varying error compensation of the subimaging region is completed,and then the error compensation of the entire imaging region is realized to ensure the quality of the imaging image.3.According to different imaging scenarios and imaging requirements,an imaging software supporting video SAR system is designed.Combined with different functional requirements,the structured design scheme of imaging software is given and implemented by modules.The imaging software uses C# language programming under Microsoft Visual Studio software development tools to realize the functions of each module,and then completes the interaction with radar,sets the relevant parameters,and controls radar transmitting and receiving echo signals;Establish efficient communication connection for data transmission and analysis storage;According to different imaging tasks,flexibly select imaging mode and corresponding imaging algorithm;The software user interface displays the imaging results and one-dimensional range profile in real time.Finally,the results of simulation experiments are given to verify the effectiveness of the algorithm,a joint test experiment of radar system and imaging software under three modes are carried out,and the imaging experiments under different scenarios are completed.The imaging results of the software and the measured data under MATLAB verify that the imaging software can work in real time and accurately.