{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T11:12:40Z","timestamp":1788433960580,"version":"build-2803163510"},"reference-count":30,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T00:00:00Z","timestamp":1788393600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Non-contact vital sign monitoring using millimeter-wave radar has emerged as a promising alternative to contact-based devices for continuous healthcare and elderly care applications. However, accurate heart rate estimation remains challenging because the weak cardiac-induced chest displacement is approximately an order of magnitude smaller than respiratory motion, and its fundamental frequency is frequently masked by higher-order respiratory harmonics. Here we propose a signal processing framework that addresses this challenge through three integrated stages: a slow-time phase correlation method that enhances the signal-to-noise ratio by coherently aggregating vital sign energy from adjacent range bins; an adaptive harmonic matching filtering approach based on complementary ensemble empirical mode decomposition that isolates and suppresses respiratory harmonic interference; and autocorrelation-based heart rate estimation. Experimental results obtained with a 77 GHz FMCW radar demonstrate that the proposed method achieves heart rate estimates within 5% error of reference wearable sensors in the presence of respiratory harmonics, with robustness confirmed through long-duration testing. This framework provides a practical solution for reliable radar-based heart rate monitoring without requiring subject-specific calibration or specialized hardware modifications.<\/jats:p>","DOI":"10.3390\/s26175587","type":"journal-article","created":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T10:10:33Z","timestamp":1788430233000},"page":"5587","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Radar-Based Heart Rate Estimation Method Under Respiratory Harmonic Interference"],"prefix":"10.3390","volume":"26","author":[{"given":"Didi","family":"Xu","sequence":"first","affiliation":[{"name":"Beijing Institute of Radio Metrology and Measurement, Beijing 100854, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"given":"Ying","family":"Li","sequence":"additional","affiliation":[{"name":"Beijing Institute of Radio Metrology and Measurement, Beijing 100854, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"software","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]},{"given":"Zinan","family":"Wu","sequence":"additional","affiliation":[{"name":"Beijing Institute of Radio Metrology and Measurement, Beijing 100854, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3675-6400","authenticated-orcid":false,"given":"Tingting","family":"Xie","sequence":"additional","affiliation":[{"name":"Beijing Institute of Radio Metrology and Measurement, Beijing 100854, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"given":"Pengwei","family":"Gong","sequence":"additional","affiliation":[{"name":"Beijing Institute of Radio Metrology and Measurement, Beijing 100854, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1109\/TBCAS.2023.3257647","article-title":"Comprehensive Comparison of Continuous-Wave and Linear-Frequency-Modulated Continuous-Wave Radars for Short-Range Vital Sign Monitoring","volume":"17","author":"Antolinos","year":"2023","journal-title":"IEEE Trans. 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