Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation

Ground moving target (GMT) is displaced and defocused in conventional synthetic aperture radar (SAR) image due to the residual phase error of non-cooperative GMT motion. In this study, a GMT imaging (GMTIm) method is proposed for highly squint SAR. As the squint angle become large, the displace and...

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Autores principales:	Shichao Xiong, Jiacheng Ni, Qun Zhang, Ying Luo, Longqiang Yu
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	SAR highly squint GMTIm image entropy region of interest Science Q
Acceso en línea:	https://doaj.org/article/2519e3d5bc8f49f8be8cae3bb7e4d3c1
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id	oai:doaj.org-article:2519e3d5bc8f49f8be8cae3bb7e4d3c1
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spelling	oai:doaj.org-article:2519e3d5bc8f49f8be8cae3bb7e4d3c12021-11-11T18:54:55ZGround Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation10.3390/rs132143732072-4292https://doaj.org/article/2519e3d5bc8f49f8be8cae3bb7e4d3c12021-10-01T00:00:00Zhttps://www.mdpi.com/2072-4292/13/21/4373https://doaj.org/toc/2072-4292Ground moving target (GMT) is displaced and defocused in conventional synthetic aperture radar (SAR) image due to the residual phase error of non-cooperative GMT motion. In this study, a GMT imaging (GMTIm) method is proposed for highly squint SAR. As the squint angle become large, the displace and defocus effect of the GMT image become severe and the geometry distortion of the GMT image cannot be ignored. The proposed method first deduced the two-dimensional (2-D) frequency domain signal of the GMT and the bulk compression function of the Range Migration Algorithm (RMA) in highly squint SAR. Then GMT ROI data are extracted and a modified minimum entropy algorithm (MMEA) is proposed to refocus the GMT image. MMEA introduces the idea of bisection into the iteration process to converge more efficiently than the previous minimum entropy method. To overcome the geometry distortion of the GMT image, an equivalent squint angle spectrum rotation method is proposed. Finally, to suppress the GMT image sidelobe, the sparse characteristic of GMT is considered and a sparse enhancement method is adopted. The proposed method can realize GMTIm in highly squint SAR where the squint angle reaches to 75 degrees. The PSNR and ISLR of point target in highly squint SAR is close to that in side-looking SAR. The simulated point target data and ship data are used to validate the effectiveness of the proposed method.Shichao XiongJiacheng NiQun ZhangYing LuoLongqiang YuMDPI AGarticleSARhighly squintGMTImimage entropyregion of interestScienceQENRemote Sensing, Vol 13, Iss 4373, p 4373 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	SAR highly squint GMTIm image entropy region of interest Science Q
spellingShingle	SAR highly squint GMTIm image entropy region of interest Science Q Shichao Xiong Jiacheng Ni Qun Zhang Ying Luo Longqiang Yu Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation
description	Ground moving target (GMT) is displaced and defocused in conventional synthetic aperture radar (SAR) image due to the residual phase error of non-cooperative GMT motion. In this study, a GMT imaging (GMTIm) method is proposed for highly squint SAR. As the squint angle become large, the displace and defocus effect of the GMT image become severe and the geometry distortion of the GMT image cannot be ignored. The proposed method first deduced the two-dimensional (2-D) frequency domain signal of the GMT and the bulk compression function of the Range Migration Algorithm (RMA) in highly squint SAR. Then GMT ROI data are extracted and a modified minimum entropy algorithm (MMEA) is proposed to refocus the GMT image. MMEA introduces the idea of bisection into the iteration process to converge more efficiently than the previous minimum entropy method. To overcome the geometry distortion of the GMT image, an equivalent squint angle spectrum rotation method is proposed. Finally, to suppress the GMT image sidelobe, the sparse characteristic of GMT is considered and a sparse enhancement method is adopted. The proposed method can realize GMTIm in highly squint SAR where the squint angle reaches to 75 degrees. The PSNR and ISLR of point target in highly squint SAR is close to that in side-looking SAR. The simulated point target data and ship data are used to validate the effectiveness of the proposed method.
format	article
author	Shichao Xiong Jiacheng Ni Qun Zhang Ying Luo Longqiang Yu
author_facet	Shichao Xiong Jiacheng Ni Qun Zhang Ying Luo Longqiang Yu
author_sort	Shichao Xiong
title	Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation
title_short	Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation
title_full	Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation
title_fullStr	Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation
title_full_unstemmed	Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation
title_sort	ground moving target imaging for highly squint sar by modified minimum entropy algorithm and spectrum rotation
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/2519e3d5bc8f49f8be8cae3bb7e4d3c1
work_keys_str_mv	AT shichaoxiong groundmovingtargetimagingforhighlysquintsarbymodifiedminimumentropyalgorithmandspectrumrotation AT jiachengni groundmovingtargetimagingforhighlysquintsarbymodifiedminimumentropyalgorithmandspectrumrotation AT qunzhang groundmovingtargetimagingforhighlysquintsarbymodifiedminimumentropyalgorithmandspectrumrotation AT yingluo groundmovingtargetimagingforhighlysquintsarbymodifiedminimumentropyalgorithmandspectrumrotation AT longqiangyu groundmovingtargetimagingforhighlysquintsarbymodifiedminimumentropyalgorithmandspectrumrotation
_version_	1718431632301490176

Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum Rotation

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