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...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-10-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/13/21/4373 |
| _version_ | 1827677932667011072 |
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| 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 |
| collection | DOAJ |
| 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. |
| first_indexed | 2024-03-10T05:53:38Z |
| format | Article |
| id | doaj.art-2519e3d5bc8f49f8be8cae3bb7e4d3c1 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T05:53:38Z |
| publishDate | 2021-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-2519e3d5bc8f49f8be8cae3bb7e4d3c12023-11-22T21:32:31ZengMDPI AGRemote Sensing2072-42922021-10-011321437310.3390/rs13214373Ground Moving Target Imaging for Highly Squint SAR by Modified Minimum Entropy Algorithm and Spectrum RotationShichao Xiong0Jiacheng Ni1Qun Zhang2Ying Luo3Longqiang Yu4Information and Navigation College, Air Force Engineering University, Xi’an 710077, ChinaInformation and Navigation College, Air Force Engineering University, Xi’an 710077, ChinaInformation and Navigation College, Air Force Engineering University, Xi’an 710077, ChinaInformation and Navigation College, Air Force Engineering University, Xi’an 710077, ChinaInformation and Navigation College, Air Force Engineering University, Xi’an 710077, ChinaGround 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.https://www.mdpi.com/2072-4292/13/21/4373SARhighly squintGMTImimage entropyregion of interest |
| spellingShingle | 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 Remote Sensing SAR highly squint GMTIm image entropy region of interest |
| title | 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_short | 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 |
| topic | SAR highly squint GMTIm image entropy region of interest |
| url | https://www.mdpi.com/2072-4292/13/21/4373 |
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