Research On Moving Target Detection Method Based On Video SAR

Video SAR not only has the advantages of traditional SAR,but also has the characteristics of high imaging frame rate and high resolution.It can achieve continuous and rapid imaging of monitoring scenes and obtain video imaging results,which can help combat requirements such as real-time detection and tracking of targets in modern military.At the same time,its all-day and all-weather imaging characteristics are more suitable for various scenarios.Moving target detection has always been a hot spot in the field of SAR imaging.The research on moving target detection for video SAR is of great significance.This thesis studies moving target detection methods based on video SAR.The main research content is as follows:1.The imaging principle of video SAR in circular mode is introduced.At the same time,in order to better study the moving target detection method,the characteristics of the echo signal of the moving target are studied,and the Doppler frequency shift caused by the speed of the moving target is analyzed.And simulation experiments are carried out.In video SAR mode,the target shadow is obvious in the imaging results.In order to further understand the characteristics of shadows,the principle of forming shadows of moving and stationary targets is analyzed,and simulation experiments are performed for SARs with different carrier frequencies,which shows that video SAR systems are more conducive to the formation of target shadows.2.Aiming at the problem of moving target detection in video SAR mode,a method of moving target detection using moving target shadow is proposed.This method utilizes the high frame rate imaging characteristics of video SAR to detect moving shadows by detecting changes in shadows in adjacent frames in the imaging results,thereby achieving detection of moving targets.Experiments were performed on the video SAR imaging results published by SNL to verify the effectiveness of the method.At the same time,in order to further improve the detection performance of the detection method,the effects of shadow quality such as: moving target speed,synthetic aperture time,scrub angle,clutter interference and other factors were studied and simulated.The analysis of influencing factors is conducive to subsequent improvement of detection performance.3.Aiming at the interference of strong echo on shadow quality,the suppression effect of different window functions on the sidelobes of strong echo signals is analyzed.Simulation experiments show that the Blackman window function is better for improving shadow quality.At the same time,based on the interference of moving target echo signals on shadow quality,a dual Pulse Repetition Frequency filtering(Dual Pulse Repetition Frequency Filtering,DPRFF)method for moving target echo signals was proposed.This method uses two different PRFs.When the Doppler frequency shift caused by the moving target speed exceeds the range of [-PRF/2,PRF/2],the frequency spectrum will be shifted by an integer multiple of PRF.Different positions can filter the echo signals of moving targets and reduce interference with target shadows.