{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:45:30Z","timestamp":1760150730315,"version":"build-2065373602"},"reference-count":35,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2023,12,26]],"date-time":"2023-12-26T00:00:00Z","timestamp":1703548800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>A high-frequency surface wave radar (HFSWR) is the only sensor that provides inexpensive surveillance for up to 200 nautical miles (NM) of the exclusive economic zone in the 3\u20135 MHz band. However, because of its long wavelength, its angular resolution is low. Multiple-input multiple-output (MIMO) technology is an attractive method to improve angular resolution. This paper proposes MIMO waveforms and their processing that can be used in HFSWR systems. This dual modulation method applies linear frequency modulation to each pulse and orthogonal polyphase codes for a few consecutive pulses to enable MIMO processing. The proposed method can effectively remove the correlation of mutual interference and exhibits excellent performance in removing multiple-time-around echoes.<\/jats:p>","DOI":"10.3390\/rs16010104","type":"journal-article","created":{"date-parts":[[2023,12,27]],"date-time":"2023-12-27T02:58:12Z","timestamp":1703645892000},"page":"104","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Linear Frequency Modulation and Orthogonal Code Modulation for Co-Located Multiple-Input Multiple-Output High-Frequency Surface Wave Radar"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5118-5509","authenticated-orcid":false,"given":"Eunhee","family":"Kim","sequence":"first","affiliation":[{"name":"Department of Defence System Engineering, Sejong University, 209 Neungdong-ro, Gwangjn-gu, Seoul 05006, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sunghwan","family":"Sohn","sequence":"additional","affiliation":[{"name":"LIGNex1 Co., 207 Mabuk-ro, Giheung-gu, Yongin-si 16911, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyunwook","family":"Moon","sequence":"additional","affiliation":[{"name":"LIGNex1 Co., 207 Mabuk-ro, Giheung-gu, Yongin-si 16911, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun Hyeok","family":"Choi","sequence":"additional","affiliation":[{"name":"LIGNex1 Co., 207 Mabuk-ro, Giheung-gu, Yongin-si 16911, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kiwon","family":"Lee","sequence":"additional","affiliation":[{"name":"LIGNex1 Co., 207 Mabuk-ro, Giheung-gu, Yongin-si 16911, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,12,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Sun, W., Ji, M., Huang, W., Ji, Y., and Dai, Y. (2020). Vessel tracking using bistatic compact HFSWR. Remote Sens., 12.","DOI":"10.3390\/rs12081266"},{"key":"ref_2","first-page":"409","article-title":"A review of high frequency surface wave radar for detection and tracking of ships","volume":"18","author":"Ponsford","year":"2010","journal-title":"Turk. J. Electr. Eng. Comput. Sci."},{"key":"ref_3","unstructured":"Ponsford, A.M., Dizaji, R.M., and Mckerracher, R. (2003, January 3\u20135). HF surface wave radar operation in adverse conditions. Proceedings of the International Conference on Radar (IEEE Cat. No. 03EX695), Adelaide, SA, Australia."},{"key":"ref_4","unstructured":"Headrick, J.M., Stuart, J.A., and Merrill, S. (2008). Radar Handbook, McGraw Hill."},{"key":"ref_5","first-page":"3504205","article-title":"DOA estimation for HFSWR target based on PSO-ELM","volume":"19","author":"Zhang","year":"2021","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1983","DOI":"10.1109\/LGRS.2017.2745048","article-title":"Enhanced target detection for HFSWR by 2-D MUSIC based on sparse recovery","volume":"14","author":"Chen","year":"2017","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Greiff, C., Giovanneschi, F., and Gonzalez-Huici, M.A. (2020, January 28\u201330). Matrix pencil method for DoA estimation with interpolated arrays. Proceedings of the 2020 IEEE International Radar Conference (RADAR), Washington, DC, USA.","DOI":"10.1109\/RADAR42522.2020.9114577"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"11844","DOI":"10.1109\/TVT.2023.3268791","article-title":"Height Measurement for Meter Wave MIMO Radar based on Matrix Pencil Under Complex Terrain","volume":"72","author":"Zheng","year":"2023","journal-title":"IEEE Trans. Veh. Technol."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Yilmazer, Y., and Sarkar, T.K. (2006, January 9\u201314). Efficient computation of the azimuth and elevation angles of the sources by using unitary matrix pencil method (2-d ump). Proceedings of the 2006 IEEE Antennas and Propagation Society International Symposium, Albuquerque, NM, USA.","DOI":"10.1109\/APS.2006.1710739"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"576","DOI":"10.1109\/TSP.2008.2007107","article-title":"Optimal polarized beampattern synthesis using a vector antenna array","volume":"57","author":"Xiao","year":"2008","journal-title":"IEEE Trans. Signal Process."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"108715","DOI":"10.1016\/j.sigpro.2022.108715","article-title":"Joint 2D-DOA estimation of coherent targets using EV sensors in MIMO radar","volume":"201","author":"Chintagunta","year":"2022","journal-title":"Signal Process."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"815","DOI":"10.1109\/JIOT.2022.3204267","article-title":"3-D positioning method for anonymous UAV based on bistatic polarized MIMO radar","volume":"10","author":"Wen","year":"2022","journal-title":"IEEE Internet Things J."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"7810","DOI":"10.1049\/joe.2019.0755","article-title":"DOA estimation with extended sparse and parametric approach in multi-carrier MIMO HFSWR","volume":"21","author":"Liu","year":"2019","journal-title":"J. Eng."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Donnet, B.J., and Longstaff, I.D. (2006, January 13\u201315). MIMO radar, techniques and opportunities. Proceedings of the 2006 European Radar Conference, Manchester, UK.","DOI":"10.1109\/EURAD.2006.280286"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Frazer, G.J., Abramovich, Y.I., Johnson, B.A., and Robey, F.C. (2008, January 26\u201330). Recent results in MIMO over-the-horizon radar. Proceedings of the 2008 IEEE Radar Conference, Rome, Italy.","DOI":"10.1109\/RADAR.2008.4720867"},{"key":"ref_16","unstructured":"Lesturgie, M. (2011, January 7\u20139). Some relevant applications of MIMO to radar. Proceedings of the 2011 12th International Radar Symposium (IRS), Leipzig, Germany."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Frazer, G.J., Abramovich, Y.I., and Johnson, B.A. (2007, January 17\u201320). Spatially waveform diverse radar: Perspectives for high frequency OTHR. Proceedings of the 2007 IEEE Radar Conference, Waltham, MA, USA.","DOI":"10.1109\/RADAR.2007.374247"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Willis, N.J. (2005). Bistatic Radar, SciTech Publishing.","DOI":"10.1049\/SBRA003E"},{"key":"ref_19","unstructured":"Riddolls, R.J. (2006). A Canadian Perspective on High-Frequency Over-the-Horizon Radar, Technical Report. DREO TR 285."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1109\/MAES.2009.5109947","article-title":"MIMO radar: Snake oil or good idea?","volume":"24","author":"Daum","year":"2009","journal-title":"IEEE Aerosp. Electron. Syst. Mag."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1090","DOI":"10.1049\/iet-rsn.2018.5075","article-title":"Random phase code for automotive MIMO radars using combined frequency shift keying-linear FMCW waveform","volume":"12","author":"Kim","year":"2018","journal-title":"IET Radar Sonar Navig."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1109\/MAES.2016.160071","article-title":"Overview of radar waveform diversity","volume":"31","author":"Blunt","year":"2016","journal-title":"IEEE Aerosp. Electron. Syst. Mag."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"106","DOI":"10.1109\/MSP.2007.904812","article-title":"MIMO radar with colocated antennas","volume":"24","author":"Li","year":"2007","journal-title":"IEEE Signal Process. Mag."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1421","DOI":"10.1109\/TAES.2016.140023","article-title":"MIMO Radar Waveform Design for Transmit Beamforming and Orthogonality","volume":"52","author":"Deng","year":"2016","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1650","DOI":"10.1109\/TAES.2009.5310326","article-title":"Orthogonal discrete frequency-coding waveform set design with minimized autocorrelation sidelobes","volume":"45","author":"Liu","year":"2009","journal-title":"IEEE Trans. Aerosp. Electron. Syst."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Yu, C., Chang, G., Ji, Y., Wang, Y., and Liu, A. (2016, January 10\u201313). DFCW-LFM analysis for MIMO HFSWR. Proceedings of the 2016 CIE International Conference on Radar (RADAR), Guangzhou, China.","DOI":"10.1109\/RADAR.2016.8059164"},{"key":"ref_27","unstructured":"Khan, H.A., and Edwards, D.J. (2006, January 24-27). Doppler problems in orthogonal MIMO radars. Proceedings of the 2006 IEEE Conference on Radar, Verona, NY, USA."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Kim, E. (2022). MIMO FMCW Radar with Doppler-Insensitive Polyphase Codes. Remote Sens., 14.","DOI":"10.3390\/rs14112595"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Linwei, W., Bo, L., Changjun, Y., and Zhe, L. (2020, January 4\u20136). LFM-CCC orthogonal waveform design for MIMO-HFSWR. Proceedings of the IET International Radar Conference (IET IRC 2020), Online.","DOI":"10.1049\/icp.2021.0707"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"4462","DOI":"10.1109\/JSEN.2018.2824824","article-title":"Orthogonal waveform with multiple diversities for MIMO radar","volume":"18","author":"Chang","year":"2018","journal-title":"IEEE Sens. J."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Bergin, J., and Guerci, J.R. (2018). MIMO Radar: Theory and Application, Artech House.","DOI":"10.1109\/MAES.2018.180062"},{"key":"ref_32","first-page":"1225","article-title":"Sequence sets in wireless communication systems: A survey","volume":"19","year":"2016","journal-title":"IEEE Commun. Surv. Tutor."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1109\/TIT.1980.1056272","article-title":"Polyphase Complementary-Codes","volume":"26","author":"Frank","year":"1980","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"5104117","DOI":"10.1109\/TGRS.2023.3270457","article-title":"Annual Characteristic Analysis of Ionosphere Reflection from Middle-Latitude HF Over-the-Horizon Radar in the Northern Hemisphere","volume":"61","author":"Ji","year":"2023","journal-title":"IEEE Trans. Geosci. Remote Sensing."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1782942","DOI":"10.1155\/2019\/1782942","article-title":"Ionospheric Clutter model for HF Sky-wave path propagation with an FMCW source","volume":"2019","author":"Yang","year":"2019","journal-title":"Int. J. Antennas Propag."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/16\/1\/104\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T21:42:16Z","timestamp":1760132536000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/16\/1\/104"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,12,26]]},"references-count":35,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2024,1]]}},"alternative-id":["rs16010104"],"URL":"https:\/\/doi.org\/10.3390\/rs16010104","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2023,12,26]]}}}