{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,12]],"date-time":"2026-05-12T16:58:33Z","timestamp":1778605113112,"version":"3.51.4"},"reference-count":34,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2022,11,30]],"date-time":"2022-11-30T00:00:00Z","timestamp":1669766400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["62071258"],"award-info":[{"award-number":["62071258"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["61971246"],"award-info":[{"award-number":["61971246"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2020ZD18"],"award-info":[{"award-number":["2020ZD18"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2021MS06004"],"award-info":[{"award-number":["2021MS06004"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2021MS06005"],"award-info":[{"award-number":["2021MS06005"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2020GG0073"],"award-info":[{"award-number":["2020GG0073"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004763","name":"Natural Science Foundation of Inner Mongolia","doi-asserted-by":"publisher","award":["62071258"],"award-info":[{"award-number":["62071258"]}],"id":[{"id":"10.13039\/501100004763","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004763","name":"Natural Science Foundation of Inner Mongolia","doi-asserted-by":"publisher","award":["61971246"],"award-info":[{"award-number":["61971246"]}],"id":[{"id":"10.13039\/501100004763","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004763","name":"Natural Science Foundation of Inner Mongolia","doi-asserted-by":"publisher","award":["2020ZD18"],"award-info":[{"award-number":["2020ZD18"]}],"id":[{"id":"10.13039\/501100004763","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004763","name":"Natural Science Foundation of Inner Mongolia","doi-asserted-by":"publisher","award":["2021MS06004"],"award-info":[{"award-number":["2021MS06004"]}],"id":[{"id":"10.13039\/501100004763","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004763","name":"Natural Science Foundation of Inner Mongolia","doi-asserted-by":"publisher","award":["2021MS06005"],"award-info":[{"award-number":["2021MS06005"]}],"id":[{"id":"10.13039\/501100004763","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004763","name":"Natural Science Foundation of Inner Mongolia","doi-asserted-by":"publisher","award":["2020GG0073"],"award-info":[{"award-number":["2020GG0073"]}],"id":[{"id":"10.13039\/501100004763","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Science and Technology Planning Project of Inner Mongolia","award":["62071258"],"award-info":[{"award-number":["62071258"]}]},{"name":"Science and Technology Planning Project of Inner Mongolia","award":["61971246"],"award-info":[{"award-number":["61971246"]}]},{"name":"Science and Technology Planning Project of Inner Mongolia","award":["2020ZD18"],"award-info":[{"award-number":["2020ZD18"]}]},{"name":"Science and Technology Planning Project of Inner Mongolia","award":["2021MS06004"],"award-info":[{"award-number":["2021MS06004"]}]},{"name":"Science and Technology Planning Project of Inner Mongolia","award":["2021MS06005"],"award-info":[{"award-number":["2021MS06005"]}]},{"name":"Science and Technology Planning Project of Inner Mongolia","award":["2020GG0073"],"award-info":[{"award-number":["2020GG0073"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The block varying pulse repetition frequency (BV-PRF) scheme applied to spaceborne squint sliding-spotlight synthetic aperture radar (SAR) can resolve large-range cell migration (RCM) and reduce azimuth signal non-uniformity. However, in the BV-PRF scheme, different raw data blocks have different PRFs, and the raw data in each block are insufficiently sampled. To resolve the two problems, a novel azimuth full-aperture pre-processing method is proposed to handle the SAR raw data formed by the BV-PRF scheme. The key point of the approach is the resampling of block data with different PRFs and the continuous splicing of azimuth data. The method mainly consists of four parts: de-skewing, resampling, azimuth continuous combination, and Doppler history recovery. After de-skewing, the raw data with different PRFs can be resampled individually to obtain a uniform azimuth sampling interval, and an appropriate azimuth time shift is introduced to ensure the continuous combination of the azimuth signal. Consequently, the resulting raw data are sufficiently and uniformly sampled in azimuth, which could be well handled by classical SAR-focusing algorithms. Simulation results on point targets validate the proposed azimuth pre-processing approach. Furthermore, compared with methods to process SAR data with continuous PRF, the proposed method is more effective.<\/jats:p>","DOI":"10.3390\/s22239328","type":"journal-article","created":{"date-parts":[[2022,11,30]],"date-time":"2022-11-30T08:46:41Z","timestamp":1669798001000},"page":"9328","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Azimuth Full-Aperture Processing of Spaceborne Squint SAR Data with Block Varying PRF"],"prefix":"10.3390","volume":"22","author":[{"given":"Zhuo","family":"Zhang","sequence":"first","affiliation":[{"name":"College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051, China"},{"name":"Inner Mongolia Key Laboratory of Radar Technology and Application, Hohhot 010051, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8045-8817","authenticated-orcid":false,"given":"Wei","family":"Xu","sequence":"additional","affiliation":[{"name":"College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051, China"},{"name":"Inner Mongolia Key Laboratory of Radar Technology and Application, Hohhot 010051, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7720-1183","authenticated-orcid":false,"given":"Pingping","family":"Huang","sequence":"additional","affiliation":[{"name":"College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051, China"},{"name":"Inner Mongolia Key Laboratory of Radar Technology and Application, Hohhot 010051, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9071-9470","authenticated-orcid":false,"given":"Weixian","family":"Tan","sequence":"additional","affiliation":[{"name":"College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051, China"},{"name":"Inner Mongolia Key Laboratory of Radar Technology and Application, Hohhot 010051, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhiqi","family":"Gao","sequence":"additional","affiliation":[{"name":"College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051, China"},{"name":"Inner Mongolia Key Laboratory of Radar Technology and Application, Hohhot 010051, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yaolong","family":"Qi","sequence":"additional","affiliation":[{"name":"College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051, China"},{"name":"Inner Mongolia Key Laboratory of Radar Technology and Application, Hohhot 010051, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Shen, S., Nie, X., and Zhang, X. (2018). Research on Synthetic Aperture Radar Processing for the Spaceborne Sliding Spotlight Mode. Sensors, 18.","DOI":"10.3390\/s18020455"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/j.isprsjprs.2020.05.016","article-title":"HyperLi-Net: A hyper-light deep learning network for high-accurate and high-speed ship detection from synthetic aperture radar imagery","volume":"167","author":"Zhang","year":"2020","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"108365","DOI":"10.1016\/j.patcog.2021.108365","article-title":"A polarization fusion network with geometric feature embedding for SAR ship classification","volume":"123","author":"Zhang","year":"2022","journal-title":"Pattern Recognit."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Xu, X., Zhang, X., and Zhang, T. (2022). Lite-YOLOv5: A Lightweight Deep Learning Detector for On-Board Ship Detection in Large-Scene Sentinel-1 SAR Images. Remote Sens., 14.","DOI":"10.3390\/rs14041018"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Xu, X., Zhang, X., Shao, Z., Shi, J., Wei, S., Zhang, T., and Zeng, T. (2022). A Group-Wise Feature Enhancement-and-Fusion Network with Dual-Polarization Feature Enrichment for SAR Ship Detection. Remote Sens., 14.","DOI":"10.3390\/rs14205276"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Zhang, T., and Zhang, X. (2022). HTC+ for SAR Ship Instance Segmentation. Remote Sens., 14.","DOI":"10.3390\/rs14102395"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Zhang, T., Zhang, X., Shi, J., and Wei, S. (2019). Depthwise Separable Convolution Neural Network for High-Speed SAR Ship Detection. Remote Sens., 11.","DOI":"10.3390\/rs11212483"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"190","DOI":"10.1016\/j.isprsjprs.2021.10.010","article-title":"Balance learning for ship detection from synthetic aperture radar remote sensing imagery","volume":"182","author":"Zhang","year":"2021","journal-title":"ISPRS J. Photogramm. Remote Sens."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Hu, X., Wang, P., Zeng, H., and Guo, Y. (2021). An Improved Equivalent Squint Range Model and Imaging Approach for Sliding Spotlight SAR Based on Highly Elliptical Orbit. Remote Sens., 13.","DOI":"10.3390\/rs13234883"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Tian, F., Suo, Z., Wang, Y., Lu, Z., Wang, Z., and Li, Z. (2022). A Unified Algorithm for the Sliding Spotlight and TOPS Modes Data Processing in Bistatic Configuration of the Geostationary Transmitter with LEO Receivers. Remote Sens., 14.","DOI":"10.3390\/rs14092006"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Kuang, H., Wang, Z., Lu, Z., Zhu, Y., Liu, Y., and Xu, M. (2019, January 26\u201329). An Improved Imaging Algorithm for High Resolution Spaceborne Squinted Sliding Spotlight SAR. Proceedings of the 2019 6th Asia-Pacific Conference on Synthetic Aperture Radar (APSAR), Xiamen, China.","DOI":"10.1109\/APSAR46974.2019.9048337"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3309","DOI":"10.1109\/TGRS.2017.2669205","article-title":"Full-Aperture Focusing of Very High Resolution Spaceborne-Squinted Sliding Spotlight SAR Data","volume":"55","author":"Sun","year":"2017","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Li, N., Niu, S., Guo, Z., Liu, Y., and Chen, J. (2018). Raw Data-Based Motion Compensation for High-Resolution Sliding Spotlight Synthetic Aperture Radar. Sensors, 18.","DOI":"10.3390\/s18030842"},{"key":"ref_14","first-page":"5202414","article-title":"Processing of Multichannel Sliding Spotlight SAR Data with Large Pulse Bandwidth and Azimuth Steering Angle","volume":"60","author":"Xu","year":"2021","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Hu, L., Wang, G., and Hou, L. (2021). Spatial-Variant SAR Range Cell Migration Correction Using Subaperture Strategy. Sensors, 21.","DOI":"10.3390\/s21072444"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Xu, W., Li, R., Fang, C., Huang, P., Tan, W., and Qi, Y. (2021). Azimuth Multichannel Reconstruction Based on Advanced Hyperbolic Range Equation. Remote Sens., 13.","DOI":"10.3390\/rs13224705"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"3750","DOI":"10.3390\/s150203750","article-title":"Modified Omega-k Algorithm for High-Speed Platform Highly-Squint Staggered SAR Based on Azimuth Non-Uniform Interpolation","volume":"15","author":"Zeng","year":"2015","journal-title":"Sensors"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Xia, Z., Jin, S., Yue, F., Yang, J., Zhang, Q., Zhao, Z., Zhang, C., Gao, W., Zhang, T., and Zhang, Y. (2022). A Novel Space-Borne High-Resolution SAR System with the Non-Uniform Hybrid Sampling Technology for Space Targets Imaging. Appl. Sci., 12.","DOI":"10.3390\/app12104848"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"089998","DOI":"10.1117\/1.JRS.8.089998","article-title":"Errata: Fast image-formation algorithm for ultrahigh-resolution airborne squint spotlight synthetic aperture radar based on adaptive sliding receive-window technique","volume":"8","author":"Yang","year":"2014","journal-title":"J. Appl. Remote Sens."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"4462","DOI":"10.1109\/TGRS.2013.2282192","article-title":"Staggered SAR: High-Resolution Wide-Swath Imaging by Continuous PRI Variation","volume":"52","author":"Villano","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"215","DOI":"10.2528\/PIER12112304","article-title":"A variable PRF imaging method for high squint diving SAR","volume":"135","author":"Xu","year":"2013","journal-title":"Prog. Electromagn. Res."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Zhang, Y., Huang, P., Xu, W., Tan, W., Wu, Z., and Li, Y. (2019, January 17\u201320). Block Varying PRI Design for High Squint Sliding-spotlight Synthetic Aperture Radar. Proceedings of the 2019 Photonics & Electromagnetics Research Symposium\u2014Fall (PIERS\u2014Fall), Xiamen, China.","DOI":"10.1109\/PIERS-Fall48861.2019.9021847"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3050","DOI":"10.1109\/JSTARS.2014.2298242","article-title":"Modification of Multichannel Reconstruction Algorithm on the SAR With Linear Variation of PRI","volume":"7","author":"Luo","year":"2014","journal-title":"Sel. Top. Appl. Earth Obs. Remote Sens. IEEE J."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Men, Z., Wang, P., Li, C., Chen, J., Liu, W., and Fang, Y. (2017). High-Temporal-Resolution High-Spatial-Resolution Spaceborne SAR Based on Continuously Varying PRF. Sensors, 17.","DOI":"10.3390\/s17081700"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Jin, Y., Liang, B., Chen, J., Xiong, Y., and Xiong, M. (2022). Real-Time Imaging Processing of Squint Spaceborne SAR with High-Resolution Based on Nonuniform PRI Design. Remote Sens., 14.","DOI":"10.3390\/rs14153725"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Zhang, Z., Xu, W., Huang, P., Tan, W., and Qi, Y. (2021, January 21\u201325). Azimuth Preprocessing of Squinted Sliding Spotlight Synthetic Aperture Radar Data with Block Varying PRF. Proceedings of the 2021 Photonics & Electromagnetics Research Symposium (PIERS), Hangzhou, China.","DOI":"10.1109\/PIERS53385.2021.9694667"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"954","DOI":"10.1109\/36.921413","article-title":"A new subaperture approach to high squint SAR processing","volume":"39","year":"2001","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Kim, H., Park, J., Chang, Y.-K., and Lee, S.-H. (2021). Optimal Attitude Maneuvering Analyses for Imaging at Squint Staring and Sliding Spotlight Modes of SAR Satellite. Aerospace, 8.","DOI":"10.3390\/aerospace8100277"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Lv, Y., Shang, M., Zhong, L., Qiu, X., and Ding, C. (2022). A Novel Imaging Scheme of Squint Multichannel SAR: First Result of GF-3 Satellite. Remote Sens., 14.","DOI":"10.3390\/rs14163962"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1368","DOI":"10.1137\/0914081","article-title":"Fast Fourier Transforms for Nonequispaced Data","volume":"14","author":"Dutt","year":"1993","journal-title":"SIAM J. Sci. Comput."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"465","DOI":"10.1080\/00401706.1995.10484391","article-title":"Fundamentals of Statistical Signal Processing: Estimation Theory","volume":"37","author":"Sengijpta","year":"1995","journal-title":"Technometrics"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Chen, S., Qiu, X., Shang, M., and Han, B. (2019). An Improved Imaging Algorithm for High-Resolution Spotlight SAR with Continuous PRI Variation Based on Modified Sinc Interpolation. Sensors, 19.","DOI":"10.3390\/s19020389"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"649","DOI":"10.1109\/19.585419","article-title":"Perfect reconstruction of digital spectrum from nonuniformly sampled signals","volume":"46","year":"1997","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"4596","DOI":"10.1109\/TGRS.2013.2282863","article-title":"Full-Aperture SAR Data Focusing in the Spaceborne Squinted Sliding-Spotlight Mode","volume":"52","author":"Xu","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/23\/9328\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:30:17Z","timestamp":1760146217000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/23\/9328"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,11,30]]},"references-count":34,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2022,12]]}},"alternative-id":["s22239328"],"URL":"https:\/\/doi.org\/10.3390\/s22239328","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,11,30]]}}}