Journal of University of Chinese Academy of Sciences >
Imaging algorithm for squint sliding spotlight SAR operating in medium-earth-orbit based on polynomial and azimuth resampling method
Received date: 2024-01-03
Revised date: 2024-03-26
Online published: 2024-04-07
The medium-earth-orbit synthetic aperture radar （MEO SAR） possesses the capability of short revisit period， high spatial resolution， and wide coverage， which has promising applications in both military and civilian fields. The MEO SAR can improve azimuth resolution by operating in sliding spotlight mode， and can enhance system flexibility through squint imaging mode. However， the increase in orbit height invalidates the assumption of azimuth invariance and the squint mode causes spectrum distortion. In this paper， first， we derive the calculation process of imaging parameters based on the polynomial signal model. Then， by introducing a new model fitting method and a deramp function， we extend the azimuth time-domain resampling method from the stripmap mode to the sliding spotlight mode， correcting the azimuth space-variant characteristics. We further propose a processing flow by combining the two-step method and the non-linear range walk correction to solve the spectrum aliasing in the squint sliding spotlight mode. Finally， the proposed method is verified through simulation experiments.
Yiqiong GUO , Mingshan REN , Heng ZHANG , Haixia YUE . Imaging algorithm for squint sliding spotlight SAR operating in medium-earth-orbit based on polynomial and azimuth resampling method[J]. Journal of University of Chinese Academy of Sciences, 2026 , 43(1) : 61 -69 . DOI: 10.7523/j.ucas.2024.009
| [1] | 黄丽佳. 中高轨道SAR成像算法研究［D］. 北京： 中国科学院研究生院， 2011. |
| [2] | 刘文康. 中高轨合成孔径雷达成像关键技术研究［D］. 西安： 西安电子科技大学， 2020. |
| [3] | Matar J， Rodriguez-Cassola M， Krieger G， et al. MEO SAR： system concepts and analysis［J］. IEEE Transactions on Geoscience and Remote Sensing， 2020， 58（2）： 1313-1324. DOI： 10.1109/TGRS.2019.2945875 . |
| [4] | Matar J， Rodriguez-Cassola M. Mission considerations for future MEO SAR systems［C］//EUSAR 2018， 12th European Conference on Synthetic Aperture Radar. Aachen， Germany. VDE， 2018：1-5. |
| [5] | Cumming I G， Wong F H C. Digital processing of synthetic aperture radar data： algorithms and implementation［M］. Boston： Artech House， 2005. |
| [6] | Huang L J， Qiu X L， Hu D H， et al. Focusing of medium-earth-orbit SAR with advanced nonlinear chirp scaling algorithm［J］. IEEE Transactions on Geoscience and Remote Sensing， 2011， 49（1）： 500-508. DOI： 10.1109/TGRS.2010.2053211 . |
| [7] | Wang P B， Liu W， Chen J， et al. A high-order imaging algorithm for high-resolution spaceborne SAR based on a modified equivalent squint range model［J］. IEEE Transactions on Geoscience and Remote Sensing， 2015， 53（3）： 1225-1235. DOI： 10.1109/TGRS.2014.2336241 . |
| [8] | Wu Y， Sun G C， Yang C， et al. Processing of very high resolution spaceborne sliding spotlight SAR data using velocity scaling［J］. IEEE Transactions on Geoscience and Remote Sensing， 2016， 54（3）： 1505-1518. DOI： 10.1109/TGRS.2015.2481923 . |
| [9] | Sun G C， Wu Y， Yang J， et al. Full-aperture focusing of very high resolution spaceborne-squinted sliding spotlight SAR data［J］. IEEE Transactions on Geoscience and Remote Sensing， 2017， 55（6）： 3309-3321. DOI： 10.1109/TGRS.2017.2669205 . |
| [10] | Ding Z G， Zheng P N， Li H， et al. Spaceborne high-squint high-resolution SAR imaging based on two-dimensional spatial-variant range cell migration correction［J］. IEEE Transactions on Geoscience and Remote Sensing， 2022， 60： 5240114. DOI： 10.1109/TGRS.2022.3222230 . |
| [11] | Zhao B J， Qi X Y， Song H J， et al. An accurate range model based on the fourth-order Doppler parameters for geosynchronous SAR［J］. IEEE Geoscience and Remote Sensing Letters， 2014， 11（1）： 205-209. DOI： 10.1109/LGRS.2013.2252878 . |
| [12] | Liu W K， Sun G C， Xia X G， et al. A modified CSA based on joint time-Doppler resampling for MEO SAR stripmap mode［J］. IEEE Transactions on Geoscience and Remote Sensing， 2018， 56（6）： 3573-3586. DOI： 10.1109/TGRS.2018.2802545 . |
| [13] | Liu W K， Sun G C， Xia X G， et al. Highly squinted MEO SAR focusing based on extended omega-K algorithm and modified joint time and Doppler resampling［J］. IEEE Transactions on Geoscience and Remote Sensing， 2019， 57（11）： 9188-9200. DOI： 10.1109/TGRS.2019.2925385 . |
| [14] | Huang L J， Qiu X L， Hu D H， et al. Medium-earth-orbit SAR focusing using range Doppler algorithm with integrated two-step azimuth perturbation［J］. IEEE Geoscience and Remote Sensing Letters， 2015， 12（3）： 626-630. DOI： 10.1109/LGRS.2014.2353674 . |
| [15] | D’Aria D， Monti Guarnieri A. High-resolution spaceborne SAR focusing by SVD-stolt［J］. IEEE Geoscience and Remote Sensing Letters， 2007， 4（4）： 639-643. DOI： 10.1109/LGRS.2007.903081 . |
| [16] | Chen J L， Sun G C， Wang Y， et al. A TSVD-NCS algorithm in range-doppler domain for geosynchronous synthetic aperture radar［J］. IEEE Geoscience and Remote Sensing Letters， 2016， 13（11）： 1631-1635. DOI： 10.1109/LGRS.2016.2599224 . |
| [17] | 谈璐璐， 盛磊. 中轨SAR系统设计及关键技术研究［J］.雷达科学与技术， 2017， 15（2）： 148-152， 158. DOI：10.3969/j.issn.1672-2337.2017.02.007 . |
| [18] | Mittermayer J， Moreira A， Loffeld O. Spotlight SAR data processing using the frequency scaling algorithm［J］. IEEE Transactions on Geoscience and Remote Sensing， 1999， 37（5）： 2198-2214. DOI： 10.1109/36.789617 . |
| [19] | Prats P， Scheiber R， Mittermayer J， et al. Processing of sliding spotlight and TOPS SAR data using baseband azimuth scaling［J］. IEEE Transactions on Geoscience and Remote Sensing， 2010， 48（2）： 770-780. DOI： 10.1109/TGRS.2009.2027701 . |
| [20] | Moreira A， Mittermayer J， Scheiber R. Extended chirp scaling algorithm for air-and spaceborne SAR data processing in stripmap and ScanSAR imaging modes［J］. IEEE Transactions on Geoscience and Remote Sensing， 1996， 34（5）： 1123-1136. DOI：10.1109/36.536528 . |
| [21] | Lanari R， Zoffoli S， Sansosti E， et al. New approach for hybrid strip-map∕spotlight SAR data focusing［J］. IEE Proceedings - Radar， Sonar and Navigation， 2001， 148（6）： 363-372. DOI： 10.1049/ip-rsn：20010662 . |
| [22] | Lanari R， Tesauro M， Sansosti E， et al. Spotlight SAR data focusing based on a two-step processing approach［J］. IEEE Transactions on Geoscience and Remote Sensing， 2001， 39（9）： 1993-2004. DOI：10.1109/36.951090 . |
| [23] | 安道祥. 高分辨率SAR成像处理技术研究［D］. 长沙： 国防科学技术大学， 2011. |
| [24] | Xing M D， Wu Y F， Zhang Y D， et al. Azimuth resampling processing for highly squinted synthetic aperture radar imaging with several modes［J］. IEEE Transactions on Geoscience and Remote Sensing， 2014， 52（7）： 4339-4352. DOI： 10.1109/TGRS.2013.2281454 . |
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