{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T04:59:12Z","timestamp":1790312352325,"version":"4.1.0"},"reference-count":29,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T00:00:00Z","timestamp":1790121600000},"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>Enhanced Loran (eLoran) provides a terrestrial complement to Global Navigation Satellite Systems (GNSSs), but tri-state pulse position modulation (PPM) demodulation remains difficult under composite interference. This study proposes a label-independent Nominal-Center (NC) sampling strategy and a Multi-Scale Spatiotemporal Network (MSST-Net). NC extracts each pulse around its predicted nominal timing anchor, thereby avoiding target-dependent actual-center alignment while preserving the displacement that encodes the PPM state. MSST-Net combines multi-scale one-dimensional convolutions, Squeeze-and-Excitation channel recalibration, bidirectional long short-term memory, temporal attention, and a distance-aware mixed ordinal loss. Under a predefined controlled simulation protocol with a group- and frame-disjoint partition, the seed-42 model was evaluated on 61,008 held-out channel-realized windows generated from 372 test pulse identities belonging to 62 pulse groups across 164 nominal SNR\u2013Stage configurations. It achieved 93.71% accuracy, 93.85% balanced accuracy, and 93.81% macro-F1. Under a separate parameter-matched cross-entropy protocol, MSST-Net (CE) achieved 92.56% accuracy, versus 91.23% for the Transformer, 89.34% for CNN-BiLSTM, and 88.29% for ResNet1D. A label-free diagnostic on 1440 receiver-recorded windows indicated a remaining simulation-to-real gap; without independently verified tri-state labels, no real-waveform accuracy was claimed. Thus, the supervised results apply to the controlled simulated benchmark and do not establish operational receiver accuracy.<\/jats:p>","DOI":"10.3390\/s26196035","type":"journal-article","created":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T14:03:26Z","timestamp":1790172206000},"page":"6035","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Robust Demodulation of eLoran Tri-State PPM via Multi-Scale Spatiotemporal Modeling"],"prefix":"10.3390","volume":"26","author":[{"given":"Zhe","family":"Li","sequence":"first","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100039, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shifeng","family":"Li","sequence":"additional","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100039, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiangbin","family":"Yuan","sequence":"additional","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100039, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruoshui","family":"Leng","sequence":"additional","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100039, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiangyi","family":"Wang","sequence":"additional","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100039, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,23]]},"reference":[{"key":"ref_1","unstructured":"International Loran Association (2007). 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