Single/Multi-Channel SAR Error Estimation Method Based On Image Measure

Synthetic Aperture Radar(SAR),as a reliable microwave remote sensing detection system,has the advantage of not being interfered by factors such as climate change and weather change.Comprehensive observation and tracking of ground objects under environmental conditions can obtain high-resolution imaging capabilities for ground monitoring in large-scale scenes.With the advent of the information age,innovative technologies and innovative thinking are flourishing.Spaceborne SAR technology has become a means of effectively and quickly grasping changes in the earth’s surface information.It has been applied in land surveying,earthquake detection,water resources survey,forestry resource evaluation,as well as in civil and military fields such as marine and seawater mapping,military situation reconnaissance,etc.For single-channel/multi-channel SAR imaging,the existence of motion error and channel error will affect the final focusing effect of SAR image,so the accurate correction algorithm for motion error and channel error is very important to realize image refocusing.Based on this,this paper conducts related research around the single/multi-channel SAR error estimation method based on image measurement.The main work of the paper is as follows:(1)Aiming at the problem of image defocus caused by motion error in single-channel SAR images,a minimum entropy self-focusing motion error correction method based on polynomial fitting optimization is proposed.Compensation of high-order phase error,compared with the traditional minimum entropy self-focusing method,this method directly iteratively estimates the polynomial coefficient of the motion error in the single-channel SAR image,which can quickly and effectively realize the refocusing of the defocused image,and at the same time It has the characteristics of fast convergence speed and high processing efficiency.(2)Aiming at the problem of the degradation of Doppler reconstruction performance caused by the phase error of multi-channel SAR channels,a minimum entropy channel error estimation method based on range Doppler imaging is proposed.Entropy method,the image used to calculate the entropy value in iterations is a fine-focus SAR image corrected for range migration.Therefore,the SAR image obtained by the error iterative estimation in this method can be directly used as the final finely focused SAR image without azimuth blur,without additional imaging processing after error estimation,optimizing the estimation and imaging processing flow,and improving the processing efficiency.(3)For the traditional channel error estimation method,when the antenna azimuth baseline is inaccurate,the estimation accuracy of the channel phase error is limited.In this paper,an image subspace method based on joint pixels is proposed to deal with this problem in image measurement,a typical joint image data vector construction method is introduced,and simulation experiments are used to evaluate the effect of four methods on the estimation accuracy of channel phase error Influence,determine the optimal joint pixel data vector construction method to achieve the best channel error estimation performance,and verify the effectiveness of the method proposed in this paper.