Research On High-resolution Imaging And Processing Method Of Radar

Synthetic Aperture Radar(SAR) is a kind of high-resolution imaging radar,SAR can obtain a wide range of radar images in real time,the principle is achieving high range resolution by using pulse compression,and using the airborne radar campaign to simulate large aperture antennas to obtain azimuth data to high-resolution radar images.Resolution is an important indicator of SAR system.High-resolution represents more information of ground targets,and we can detect and identify the target more accurately. The high-resolution SAR imaging have a very important application prospects.Compared with the traditional SAR imaging processing techniques,highresolution SAR proposes special requirements in imaging processing technology and motion compensation.In this paper, from the two aspects of improving rang resolution and motion compensation, we research range high-resolution imaging technology based on broadband synthesis technology and autofocus BP algorithm.The specific work and innovation as follows:1.Firstly,SAR echo model is introduced.Pulse compression technology and factors of range resolution are described.Then we Analyze the principles of broadband synthesis technology improving range resolution, noting broadband synthesis technology can effectively improve the range resolution;Finally we introduce the principles of autofocus algorithm briefly.2.We study the frequency domain wideband synthetic methods of stepped frequency SAR.First,the basic principles of the frequency domain wideband synthetic methods systematically is studied.According to the sequencing of sub-band synthesis and range compression,wideband frequency domain synthesis method is divided into two ways,one is compression before synthetic,the other one is synthetic before compression.In consideration of sub-band overlay error of Broadband synthesis method,we propose a zero superposition method,and describe the principles of the algorithm and process steps in detail,then combine with simulation results demonstrate the effectiveness of the method of superposition of zero.3.We study a high precision motion error compensation method which is suitable for BP algorithm,which is estimated antenna phase center(APC) errors for autofocus BP algorithm.Firstly,We analysis the phase error.Then we establish antenna phase error model.Finally we propose a high-precision motion error compensation method for BP algorithm.In this method,on the basis of different image focusing performance evaluation criteria,use optimization techniques APC error estimation,then use the corrected APC for BP imaging.The memory requirement is greatly reduced compared with the autofocus BP since the per-pulse back projected values need not to be stored.