{"title":"A Two-Step Motion Compensation Method for Polar Format Images of Terahertz SAR Based on Echo Data","authors":"Shaowen Luo;Qiuyan Wang;Yinwei Li;Xiaolong Chen;Yiming Zhu","doi":"10.1109/JSTARS.2024.3461332","DOIUrl":null,"url":null,"abstract":"Terahertz synthetic aperture radar (THz SAR) has great potential in the field of remote sensing due to its high resolution and high frame rate. However, THz SAR is very sensitive to motion errors, making even small 2-D error caused by motion error and polar format algorithm (PFA) seriously affect the image quality. Existing microwave SAR autofocusing methods only estimate the error of a single dimension, which cannot meet the accuracy requirements of THz SAR for 2-D error compensation. In this article, a two-step motion compensation method for polar format images of THz SAR based on echo data is proposed. First, by analyzing the conversion model of polar coordinate format, the node where the 2-D error coupling occurs is determined. On this basis, a coarse compensation based on low-frequency fitting is proposed in front of this node to reduce the influence of PFA on the error coupling of 2-D signals. The method not only preserves the correction of the inherent range cell migration by PFA but also eliminates the interference of PFA to the subsequent error compensation processing. Second, to solve the problem that a single compensation method cannot meet the accuracy requirements of THz SAR, the maximum contrast method after polar coordinate format conversion is used for precision compensation. The effectiveness of the proposed method is verified through simulation and actual measurement data processing of 0.22-THz airborne spotlight SAR system.","PeriodicalId":13116,"journal":{"name":"IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing","volume":null,"pages":null},"PeriodicalIF":4.7000,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10680337","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing","FirstCategoryId":"5","ListUrlMain":"https://ieeexplore.ieee.org/document/10680337/","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, ELECTRICAL & ELECTRONIC","Score":null,"Total":0}
引用次数: 0
Abstract
Terahertz synthetic aperture radar (THz SAR) has great potential in the field of remote sensing due to its high resolution and high frame rate. However, THz SAR is very sensitive to motion errors, making even small 2-D error caused by motion error and polar format algorithm (PFA) seriously affect the image quality. Existing microwave SAR autofocusing methods only estimate the error of a single dimension, which cannot meet the accuracy requirements of THz SAR for 2-D error compensation. In this article, a two-step motion compensation method for polar format images of THz SAR based on echo data is proposed. First, by analyzing the conversion model of polar coordinate format, the node where the 2-D error coupling occurs is determined. On this basis, a coarse compensation based on low-frequency fitting is proposed in front of this node to reduce the influence of PFA on the error coupling of 2-D signals. The method not only preserves the correction of the inherent range cell migration by PFA but also eliminates the interference of PFA to the subsequent error compensation processing. Second, to solve the problem that a single compensation method cannot meet the accuracy requirements of THz SAR, the maximum contrast method after polar coordinate format conversion is used for precision compensation. The effectiveness of the proposed method is verified through simulation and actual measurement data processing of 0.22-THz airborne spotlight SAR system.
期刊介绍:
The IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing addresses the growing field of applications in Earth observations and remote sensing, and also provides a venue for the rapidly expanding special issues that are being sponsored by the IEEE Geosciences and Remote Sensing Society. The journal draws upon the experience of the highly successful “IEEE Transactions on Geoscience and Remote Sensing” and provide a complementary medium for the wide range of topics in applied earth observations. The ‘Applications’ areas encompasses the societal benefit areas of the Global Earth Observations Systems of Systems (GEOSS) program. Through deliberations over two years, ministers from 50 countries agreed to identify nine areas where Earth observation could positively impact the quality of life and health of their respective countries. Some of these are areas not traditionally addressed in the IEEE context. These include biodiversity, health and climate. Yet it is the skill sets of IEEE members, in areas such as observations, communications, computers, signal processing, standards and ocean engineering, that form the technical underpinnings of GEOSS. Thus, the Journal attracts a broad range of interests that serves both present members in new ways and expands the IEEE visibility into new areas.