{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,14]],"date-time":"2025-10-14T00:49:56Z","timestamp":1760402996956,"version":"build-2065373602"},"reference-count":32,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2021,4,1]],"date-time":"2021-04-01T00:00:00Z","timestamp":1617235200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2018YFC0825804"],"award-info":[{"award-number":["2018YFC0825804"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The coupling between range and azimuth dimensions is the main obstacle for highly squinted synthetic aperture radar (SAR) data focusing. Range walk correction (RWC) processing is effective to remove the linear coupling term, but the residual high order range cell migration (RCM) parts are spatial-variant in both range and azimuth dimensions. In this paper, we propose a precise spatial-variant range cell migration correction (RCMC) method with subaperture processing. The method contains two stages. Firstly, the main component of range-variant RCM is corrected in the coarse RCMC stage. Secondly, data are derived into azimuth subapertures (SAs), an SA-image-domain RCMC is developed by interp correction, where the SA image is obtained using a modified spectrum analysis (SPECAN) algorithm by establishing the relationship between Doppler frequency and residual spatial-variant RCM. In the proposed algorithm, precise compensation of space-variant RCM is implemented by SA processing, which is designed for a better practicality in real-time processing system. Simulated and real measured data experiments are designed to validate the effectiveness of the proposed approach for highly squinted SAR imaging.<\/jats:p>","DOI":"10.3390\/s21072444","type":"journal-article","created":{"date-parts":[[2021,4,1]],"date-time":"2021-04-01T23:05:11Z","timestamp":1617318311000},"page":"2444","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Spatial-Variant SAR Range Cell Migration Correction Using Subaperture Strategy"],"prefix":"10.3390","volume":"21","author":[{"given":"Liping","family":"Hu","sequence":"first","affiliation":[{"name":"Science and Technology on Electromagnetic Scattering Laboratory, Beijing Institute of Environmental Features, Beijing 100854, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2435-2970","authenticated-orcid":false,"given":"Guanyong","family":"Wang","sequence":"additional","affiliation":[{"name":"Beijing Institute of Radio Measurement, Beijing 100854, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lin","family":"Hou","sequence":"additional","affiliation":[{"name":"Beijing Aerohydrodynamic Frontier Research Center, Beijing 100074, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,4,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4448","DOI":"10.1109\/TGRS.2018.2820102","article-title":"Simultaneous Range and Cross-Range Variant Phase Error Estimation and Compensation for Highly Squinted SAR Imaging","volume":"56","author":"Ran","year":"2018","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"51211","DOI":"10.1109\/ACCESS.2019.2911554","article-title":"High-resolution imaging of multi-channel forward-looking synthetic aperture radar under curve trajectory","volume":"7","author":"Lu","year":"2019","journal-title":"IEEE Access"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"74303","DOI":"10.1109\/ACCESS.2018.2873739","article-title":"A novel focus approach for squint mode multi-channel in azimuth high-resolution and wide-swath SAR imaging processing","volume":"6","author":"Zhang","year":"2018","journal-title":"IEEE Access"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3202","DOI":"10.1109\/TGRS.2011.2180392","article-title":"A robust motion compensation approach for UAV SAR imagery","volume":"50","author":"Zhang","year":"2012","journal-title":"IEEE Trans. Geosci. Remot Sens."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Wang, G., Zhang, M., Huang, Y., Zhang, L., and Wang, F. (2019). Robust two-dimensional spatial-variant map-drift algorithm for UAV SAR autofocusing. Remote Sens., 11.","DOI":"10.3390\/rs11030340"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"724","DOI":"10.1109\/LGRS.2017.2676118","article-title":"Spectrum-oriented FFBP algorithm in quasi-polar grid for SAR imaging on maneuvering platform","volume":"14","author":"Yang","year":"2017","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"7086","DOI":"10.1109\/TGRS.2018.2848249","article-title":"A frequency domain backprojection algorithm based on local cartesian coordinate and subregion range migration correction for high-squint SAR mounted on maneuvering platforms","volume":"56","author":"Bie","year":"2018","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"481","DOI":"10.1049\/el.2019.0237","article-title":"Space-variant RCMC method for squint beam-steering SAR imaging on high-speed manoeuvring platforms","volume":"55","author":"Bie","year":"2019","journal-title":"Electron. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"760","DOI":"10.1109\/TAES.2003.1238734","article-title":"Synthetic-aperture radar processing using fast factorized back-projection","volume":"39","author":"Ulander","year":"2003","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1460","DOI":"10.1109\/LGRS.2013.2295326","article-title":"A fast BP algorithm with wavenumber spectrum fusion for high-resolution spotlight SAR imaging","volume":"11","author":"Zhang","year":"2014","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Zhang, M., Wang, G., and Zhang, L. (2017). Precise aperture-dependent motion compensation with frequency domain fast back-projection algorithm. Sensors, 17.","DOI":"10.3390\/s17112454"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"194","DOI":"10.1109\/7.78293","article-title":"SAR data focusing using seismic migration techniques","volume":"27","author":"Cafforio","year":"1991","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"706","DOI":"10.1109\/36.158864","article-title":"A comparison of range-Doppler and wavenumber domain SAR focusing algorithms","volume":"30","author":"Bamler","year":"1992","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1049\/ip-rsn:20045087","article-title":"Extended wavenumber-domain synthetic aperture radar focusing with integrated motion compensation","volume":"153","author":"Reigber","year":"2006","journal-title":"IEE Proc.-Radar Sonar Navig."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"611","DOI":"10.1109\/36.581976","article-title":"Signal properties of spaceborne squintmode SAR","volume":"35","author":"Davidson","year":"1997","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"946","DOI":"10.1109\/36.921412","article-title":"New application of nonlinear chirp scaling in SAR data processing","volume":"39","author":"Wong","year":"2001","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"150","DOI":"10.1109\/LGRS.2012.2195634","article-title":"Focus improvement of high-squint SAR based on azimuth dependence of quadratic range cell migration correction","volume":"10","author":"Zhang","year":"2013","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1109\/LGRS.2014.2329554","article-title":"Highly squint SAR data focusing based on Keystone transform and azimuth extended nonlinear chirp scaling","volume":"12","author":"Sun","year":"2015","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2564","DOI":"10.1109\/JSEN.2016.2521400","article-title":"Focus improvement for squint FMCW-SAR data using modified inverse Chirp-Z transform based on spatial-variant linear range cell migration correction and series inversion","volume":"6","author":"Li","year":"2016","journal-title":"IEEE Sensors J."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1109\/LGRS.2018.2800105","article-title":"Focus high-resolution highly squint SAR data using azimuth-variant residual RCMC and extended nonlinear chirp scaling based on a new circle model","volume":"5","author":"Zhong","year":"2018","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1109\/JSTARS.2016.2569561","article-title":"Focus improvement for high resolution highly squinted SAR imaging based on 2-D spatial-variant linear and quadratic RCMs correction and azimuth-dependent Doppler equalization","volume":"10","author":"Li","year":"2017","journal-title":"IEEE J. Sel. Topics Appl. Earth Observ. Remote Sens."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3595","DOI":"10.1109\/TGRS.2012.2183606","article-title":"Extended nonlinear chirp scaling algorithm for high-resolution highly squint SAR data focusing","volume":"50","author":"An","year":"2012","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"5547","DOI":"10.1109\/TGRS.2017.2709907","article-title":"Two-stage focusing algorithm for highly squinted synthetic aperture radar imaging","volume":"55","author":"Zhang","year":"2017","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2668","DOI":"10.1109\/36.803414","article-title":"Time-varying step transform for high squint SAR imaging","volume":"37","author":"Sun","year":"1999","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","first-page":"22","article-title":"A new subaperture approach to high squint SAR processing","volume":"39","author":"Yeo","year":"2001","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1109\/LGRS.2010.2053837","article-title":"A new improved step transform algorithm for highly squint SAR imaging","volume":"8","author":"Li","year":"2011","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"692","DOI":"10.1109\/LGRS.2012.2219033","article-title":"Azimuth overlapped subaperture algorithm in frequency domain for highly squinted synthetic aperture radar","volume":"10","author":"Tang","year":"2013","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"6718","DOI":"10.1109\/TGRS.2015.2447393","article-title":"Subaperture approach based on azimuth-dependent range cell migration correction and azimuth focusing parameter equalization for maneuvering high-squint-mode SAR","volume":"53","author":"Zeng","year":"2005","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_29","unstructured":"Cumming, I., and Wong, F. (2005). Digital Processing of Synthetic Aperture Radar Data: Algorithm and Implementation, Artech House."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1109\/LGRS.2006.885862","article-title":"A two-dimensional spectra for bistatic SAR processing using series reversion","volume":"4","author":"Neo","year":"2007","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Wang, G., Zhang, L., and Hu, Q. (2016, January 10\u201313). A novel range cell migration correction algorithm for highly squinted SAR imaging. Proceedings of the 2016 CIE International Conference on Radar, Guangzhou, China.","DOI":"10.1109\/RADAR.2016.8059219"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"204","DOI":"10.1049\/iet-rsn.2016.0195","article-title":"Precise aperture-dependent motion compensation for high-resolution synthetic aperture radar imaging","volume":"11","author":"Wang","year":"2017","journal-title":"IET Radar Sonar Navig."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/7\/2444\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T14:10:58Z","timestamp":1760364658000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/7\/2444"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,4,1]]},"references-count":32,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2021,4]]}},"alternative-id":["s21072444"],"URL":"https:\/\/doi.org\/10.3390\/s21072444","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2021,4,1]]}}}