{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,6]],"date-time":"2026-07-06T15:38:19Z","timestamp":1783352299226,"version":"3.54.6"},"reference-count":23,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2024,6,6]],"date-time":"2024-06-06T00:00:00Z","timestamp":1717632000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Key R&amp;D Program of China and Shandong Province","award":["2021YFB3901300"],"award-info":[{"award-number":["2021YFB3901300"]}]},{"name":"National Key R&amp;D Program of China and Shandong Province","award":["41974032"],"award-info":[{"award-number":["41974032"]}]},{"name":"National Key R&amp;D Program of China and Shandong Province","award":["42274019"],"award-info":[{"award-number":["42274019"]}]},{"name":"National Natural Science Foundation of China","award":["2021YFB3901300"],"award-info":[{"award-number":["2021YFB3901300"]}]},{"name":"National Natural Science Foundation of China","award":["41974032"],"award-info":[{"award-number":["41974032"]}]},{"name":"National Natural Science Foundation of China","award":["42274019"],"award-info":[{"award-number":["42274019"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The Global Navigation Satellite System (GNSS) can be utilized for long-distance and high-precision time transmission. With the ongoing development of low Earth orbit (LEO) satellites and the rapidly changing geometric relationships between them, the convergence rate of ambiguity parameters in Precise Point Positioning (PPP) algorithms has increased, enabling fast and reliable time transfer. In this paper, GPS is used as an experimental case, the LEO satellite constellation is designed, and simulated LEO observation data are generated. Then, using the GPS observation data provided by IGS, a LEO-enhanced PPP model is established. The LEO-augmented PPP model is employed to facilitate faster and more reliable high-precision time transfer. The application of the LEO-augmented PPP model to time transfer is examined and discussed through experimental examples. These examples show multiple types of time transfer links, and the experimental outcomes are uniform. GPS + LEO is compared with exclusive GPS time transfer schemes. The clock offset of the time transfer link for the GPS + LEO scheme converges more swiftly, meaning that the time required for the clock offset to reach a stable level is the briefest. In this paper, standard deviation is employed to assess stability, and Allan deviation is utilized to assess frequency stability. The results show that the clock offset stability and frequency stability achieved by the GPS + LEO scheme are superior within the convergence time range. Controlled experiments with different numbers of satellites for LEO enhancement indicate that time transfer performance can be improved by increasing the number of satellites. As a result, augmenting GPS tracking data with LEO observations enhances the time transfer service compared to GPS alone.<\/jats:p>","DOI":"10.3390\/rs16112044","type":"journal-article","created":{"date-parts":[[2024,6,6]],"date-time":"2024-06-06T12:04:28Z","timestamp":1717675468000},"page":"2044","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Study of Fast and Reliable Time Transfer Methods Using Low Earth Orbit Enhancement"],"prefix":"10.3390","volume":"16","author":[{"given":"Mingyue","family":"Liu","sequence":"first","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Shu Yuan Road, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Yu Quan Road, Beijing 100049, China"},{"name":"Key Laboratory of Lime Reference and Applications, Chinese Academy of Sciences, Shu Yuan Road, Xi\u2019an 710600, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4706-5373","authenticated-orcid":false,"given":"Rui","family":"Tu","sequence":"additional","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Shu Yuan Road, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Yu Quan Road, Beijing 100049, China"},{"name":"Key Laboratory of Lime Reference and Applications, Chinese Academy of Sciences, Shu Yuan Road, Xi\u2019an 710600, China"},{"name":"College of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao 266590, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3198-970X","authenticated-orcid":false,"given":"Qiushi","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Information and Navigation, Air Force Engineering University, East of Feng Gao Road, Xi\u2019an 710077, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qi","family":"Li","sequence":"additional","affiliation":[{"name":"Qilu Aerospace Information Research Institute, No. 9 Kuang Yuan Road, Jinan 250100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junmei","family":"Chen","sequence":"additional","affiliation":[{"name":"Qilu Aerospace Information Research Institute, No. 9 Kuang Yuan Road, Jinan 250100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9991-9310","authenticated-orcid":false,"given":"Pengfei","family":"Zhang","sequence":"additional","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Shu Yuan Road, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Yu Quan Road, Beijing 100049, China"},{"name":"Key Laboratory of Lime Reference and Applications, Chinese Academy of Sciences, Shu Yuan Road, Xi\u2019an 710600, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaochun","family":"Lu","sequence":"additional","affiliation":[{"name":"National Time Service Center, Chinese Academy of Sciences, Shu Yuan Road, Xi\u2019an 710600, China"},{"name":"University of Chinese Academy of Sciences, Yu Quan Road, Beijing 100049, China"},{"name":"Key Laboratory of Lime Reference and Applications, Chinese Academy of Sciences, Shu Yuan Road, Xi\u2019an 710600, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,6,6]]},"reference":[{"key":"ref_1","first-page":"669","article-title":"The research of key technology and approach for time and frequency transfer based on GNSS carrier phase observation","volume":"49","author":"Zhang","year":"2020","journal-title":"Acta Geod. 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