{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T15:29:37Z","timestamp":1783610977934,"version":"3.55.0"},"reference-count":31,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,6,15]],"date-time":"2023-06-15T00:00:00Z","timestamp":1686787200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"LIG Nex1 Co., Ltd."}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Frequency-modulated continuous wave (FMCW) radar system synchronization using external clock signals can cause repeated Range-Doppler (R-D) map corruption when clock signal asynchronization problems occur between the transmitter and receiver. In this paper, we propose a signal processing method for the reconstruction of the corrupted R-D map owing to the FMCW radar\u2019s asynchronization. After calculating the image entropy for each R-D map, the corrupted ones are extracted and reconstructed using the normal R-D maps acquired before and after the individual maps. To verify the effectiveness of the proposed method, three target detection experiments were conducted: a human target detection in an indoor environment and a wide place and a moving bike-rider target detection in an outdoor environment. The corrupted R-D map sequence of observed targets in each case was reconstructed properly and showed the validity by comparing the map-by-map range and speed changes in the detected target with the ground-truth information of the target.<\/jats:p>","DOI":"10.3390\/s23125605","type":"journal-article","created":{"date-parts":[[2023,6,16]],"date-time":"2023-06-16T02:54:33Z","timestamp":1686884073000},"page":"5605","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Reconstruction of Range-Doppler Map Corrupted by FMCW Radar Asynchronization"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1999-5242","authenticated-orcid":false,"given":"Kyung-Min","family":"Lee","sequence":"first","affiliation":[{"name":"Department of Electrical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang 37673, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1145-2064","authenticated-orcid":false,"given":"In-Seong","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, Yeungnam University, 280 Daehak-ro, Gyeongsan 38541, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4777-2553","authenticated-orcid":false,"given":"Hee-Sub","family":"Shin","sequence":"additional","affiliation":[{"name":"LIG Nex1 Co., Ltd., Yongin 13488, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6576-6467","authenticated-orcid":false,"given":"Jae-Woo","family":"Ok","sequence":"additional","affiliation":[{"name":"LIG Nex1 Co., Ltd., Yongin 13488, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3837-1494","authenticated-orcid":false,"given":"Jae-Hyuk","family":"Youn","sequence":"additional","affiliation":[{"name":"LIG Nex1 Co., Ltd., Yongin 13488, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2255-6531","authenticated-orcid":false,"given":"Eung-Noh","family":"You","sequence":"additional","affiliation":[{"name":"LIG Nex1 Co., Ltd., Yongin 13488, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4939-3274","authenticated-orcid":false,"given":"Jong-Ryul","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Electrical and Electronics Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1200-5282","authenticated-orcid":false,"given":"Kyung-Tae","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang 37673, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,15]]},"reference":[{"key":"ref_1","unstructured":"Jankiraman, M. (2018). FMCW Radar Design, Artech House."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Moll, J., Salman, R., Pozdniakov, D., Nuber, A., Friedman, H., Arnold, P., M\u00e4lzer, M., and Krozer, V. (2018, January 12\u201314). Motion sensing of a wind turbine prototype using a bistatic FMCW Doppler radar sensor. Proceedings of the 2018 11th German Microwave Conference (GeMiC), Freiburg, Germany.","DOI":"10.23919\/GEMIC.2018.8335038"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2618","DOI":"10.1109\/TGRS.2018.2875695","article-title":"All-directions through-the-wall imaging using a small number of moving omnidirectional bi-static FMCW transceivers","volume":"57","author":"Yektakhah","year":"2018","journal-title":"IEEE Trans. Geosci. Remot. Sens."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"4774","DOI":"10.1109\/TMTT.2021.3101655","article-title":"Vital sign detection in any orientation using a distributed radar network via modified independent component analysis","volume":"69","author":"Ren","year":"2021","journal-title":"IEEE Trans. Microw. Theory Tech."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2017","DOI":"10.1109\/TAES.2013.6558035","article-title":"Bistatic FMCW SAR signal model and imaging approach","volume":"49","author":"Liu","year":"2013","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1109\/TAES.2021.3096875","article-title":"Radar cross section based statistical recognition of UAVs at microwave frequencies","volume":"58","author":"Ezuma","year":"2021","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"833","DOI":"10.1049\/iet-rsn.2019.0471","article-title":"Radar cross-sections of pedestrians at automotive radar frequencies using ray tracing and point scatterer modelling","volume":"14","author":"Deep","year":"2020","journal-title":"IET Radar Sonar Navig."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Willis, N.J. (2005). Bistatic Radar, SciTech Publishing.","DOI":"10.1049\/SBRA003E"},{"key":"ref_9","unstructured":"Cherniakov, M. (2001). Bistatic Radar: Principles and Practice, John Wiley & Sons."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Cherniakov, M. (2008). Bistatic Radar: Emerging Technology, John Wiley & Sons.","DOI":"10.1002\/9780470985755"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"20228","DOI":"10.1109\/ACCESS.2017.2756075","article-title":"Reduced complexity multipath clutter rejection approach for DRM-based HF passive bistatic radar","volume":"5","author":"Zhao","year":"2017","journal-title":"IEEE Access"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Du, H., Fan, C., Cao, C., Xu, Z., and Huang, X. (2020, January 8\u201311). A novel NLOS target localization method with a synthetic bistatic MMW radar. Proceedings of the 2020 IEEE 11th Sensor Array and Multichannel Signal Processing Workshop (SAM), Hangzhou, China.","DOI":"10.1109\/SAM48682.2020.9104299"},{"key":"ref_13","unstructured":"Krieger, G. (2006, January 25\u201327). Advanced bistatic and multistatic SAR concepts and applications. Proceedings of the European Conference on Synthetic Aperture Radar (EUSAR), Leipzig, Germany."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1049\/ip-rsn:20045117","article-title":"ONERA-DLR bistatic SAR campaign: Planning, data acquisition, and first analysis of bistatic scattering behaviour of natural and urban targets","volume":"153","author":"Cantalloube","year":"2006","journal-title":"IEE Proc.-Radar Sonar Navig."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1750","DOI":"10.1109\/IGARSS.2004.1370671","article-title":"Synchronisation of bistatic radar systems","volume":"Volume 3","author":"Weib","year":"2004","journal-title":"Proceedings of the IGARSS 2004, 2004 IEEE International Geoscience and Remote Sensing Symposium"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2219","DOI":"10.1109\/ICCCAS.2006.285118","article-title":"Synchronization technology of bistatic radar system","volume":"Volume 4","author":"Yulin","year":"2006","journal-title":"Proceedings of the 2006 International Conference on Communications, Circuits and Systems"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Reza, M., Amir, M.M.H., Imran, M., Pandey, G., Camponeschi, F., Maresca, S., Scotti, F., Serafino, G., Malacarne, A., and Porzi, C. (2022). Multi-Static Multi-Band Synthetic Aperture Radar (SAR) Constellation Based on Integrated Photonic Circuits. Electronics, 11.","DOI":"10.3390\/electronics11244151"},{"key":"ref_18","unstructured":"Krieger, G., and De Zan, F. (2012, January 23\u201326). Relativistic effects in bistatic SAR processing and system synchronization. Proceedings of the EUSAR 2012, 9th European Conference on Synthetic Aperture Radar, Nurnberg, Germany."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Liang, D., Zhang, H., Cai, Y., Liu, K., and Zhang, K. (2021). An advanced phase synchronization scheme based on coherent integration and waveform diversity for bistatic SAR. Remote Sens., 13.","DOI":"10.3390\/rs13050981"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Beasley, P., and Ritchie, M. (2022, January 24\u201327). Multistatic Radar Synchronisation Using COTS GPS Disciplined Oscillators. Proceedings of the Iet Radar Conference 2022, Edinburgh, UK.","DOI":"10.1049\/icp.2022.2356"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3519","DOI":"10.1109\/TGRS.2007.906140","article-title":"Signal processing for FMCW SAR","volume":"45","author":"Meta","year":"2007","journal-title":"IEEE Trans. Geosci. Remot. Sens."},{"key":"ref_22","unstructured":"Carrara, W.G., Goodman, R.S., and Majewski, R.M. (1995). Spotlight Synthetic Aperture Radar: Signal Processing Algorithms, Artech House Inc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1240","DOI":"10.1109\/7.805442","article-title":"Autofocusing of ISAR images based on entropy minimization","volume":"35","author":"Xi","year":"1999","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_24","first-page":"2","article-title":"Shannon entropy, Renyi entropy, and information","volume":"9","author":"Bromiley","year":"2004","journal-title":"Stat. Inf. Ser."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1080\/2151237X.2007.10129236","article-title":"Adaptive thresholding using the integral image","volume":"12","author":"Bradley","year":"2007","journal-title":"J. Graph. Tools"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Roy, P., Dutta, S., Dey, N., Dey, G., Chakraborty, S., and Ray, R. (2014, January 10\u201311). Adaptive thresholding: A comparative study. Proceedings of the 2014 International Conference on Control, Instrumentation, Communication and Computational Technologies (ICCICCT), Kanyaku, India.","DOI":"10.1109\/ICCICCT.2014.6993140"},{"key":"ref_27","unstructured":"Singh, T.R., Roy, S., Singh, O.I., Sinam, T., and Singh, K.M. (2012). A new local adaptive thresholding technique in binarization. arXiv."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1016\/j.probengmech.2015.09.015","article-title":"Compressive sensing based stochastic process power spectrum estimation subject to missing data","volume":"44","author":"Comerford","year":"2016","journal-title":"Probabilistic Eng. Mech."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2294","DOI":"10.1016\/j.neucom.2017.11.004","article-title":"Group sparsity residual constraint for image denoising with external nonlocal self-similarity prior","volume":"275","author":"Zha","year":"2018","journal-title":"Neurocomputing"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3368","DOI":"10.1109\/TAES.2022.3210474","article-title":"Sparsity-driven Inverse Synthetic Aperture Radar Imaging using Accelerated Meta-Heuristic Optimization","volume":"59","author":"Lee","year":"2022","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1182","DOI":"10.1109\/TCSVT.2016.2527181","article-title":"Video compressive sensing reconstruction via reweighted residual sparsity","volume":"27","author":"Zhao","year":"2016","journal-title":"IEEE Trans. Circuits Syst. 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