{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,8]],"date-time":"2026-02-08T00:38:16Z","timestamp":1770511096153,"version":"3.49.0"},"reference-count":71,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2018,11,14]],"date-time":"2018-11-14T00:00:00Z","timestamp":1542153600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["41704002"],"award-info":[{"award-number":["41704002"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["91638203"],"award-info":[{"award-number":["91638203"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"China Postdoc Science Foundation","award":["2017M620337"],"award-info":[{"award-number":["2017M620337"]}]},{"name":"the Fundamental Research Funds for the Central Universities","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A low Earth orbiter (LEO)-based navigation signal augmentation system is considered as a complementary of current global navigation satellite systems (GNSS), which can accelerate precise positioning convergence, strengthen the signal power, and improve signal quality. Wuhan University is dedicated to LEO-based navigation signal augmentation research and launched one scientific experimental satellite named Luojia-1A. The satellite is capable of broadcasting dual-frequency band ranging signals over China. The initial performance of the Luojia-1A satellite navigation augmentation system is assessed in this study. The ground tests indicate that the phase noise of the oscillator is sufficiently low to support the intended applications. The field ranging tests achieve 2.6 m and 0.013 m ranging precision for the pseudorange and carrier phase measurements, respectively. The in-orbit test shows that the internal precision of the ephemeris is approximate 0.1 m and the clock stability is 3 \u00d7 10\u221210. The pseudorange and carrier phase measurement noise evaluated from the geometry-free combination is about 3.3 m and 1.8 cm. Overall, the Luojia-1A navigation augmentation system is capable of providing useable LEO navigation augmentation signals with the empirical user equivalent ranging error (UERE) no worse than 3.6 m, which can be integrated with existing GNSS to improve the real-time navigation performance.<\/jats:p>","DOI":"10.3390\/s18113919","type":"journal-article","created":{"date-parts":[[2018,11,14]],"date-time":"2018-11-14T10:58:22Z","timestamp":1542193102000},"page":"3919","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":73,"title":["Initial Assessment of the LEO Based Navigation Signal Augmentation System from Luojia-1A Satellite"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1887-6222","authenticated-orcid":false,"given":"Lei","family":"Wang","sequence":"first","affiliation":[{"name":"State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China"},{"name":"Collaborative Innovation Center for Geospatial Technology, Wuhan, 430079, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6683-2342","authenticated-orcid":false,"given":"Ruizhi","family":"Chen","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China"},{"name":"Collaborative Innovation Center for Geospatial Technology, Wuhan, 430079, China"}]},{"given":"Deren","family":"Li","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China"},{"name":"Collaborative Innovation Center for Geospatial Technology, Wuhan, 430079, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3987-5336","authenticated-orcid":false,"given":"Guo","family":"Zhang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China"},{"name":"Collaborative Innovation Center for Geospatial Technology, Wuhan, 430079, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9692-822X","authenticated-orcid":false,"given":"Xin","family":"Shen","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China"},{"name":"Collaborative Innovation Center for Geospatial Technology, Wuhan, 430079, China"}]},{"given":"Baoguo","family":"Yu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Satellite Navigation System and Equipment Technology, Shijiazhuang 050000, China"}]},{"given":"Cailun","family":"Wu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Satellite Navigation System and Equipment Technology, Shijiazhuang 050000, China"}]},{"given":"Song","family":"Xie","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Satellite Navigation System and Equipment Technology, Shijiazhuang 050000, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7257-6186","authenticated-orcid":false,"given":"Peng","family":"Zhang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0722-028X","authenticated-orcid":false,"given":"Ming","family":"Li","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China"},{"name":"Collaborative Innovation Center for Geospatial Technology, Wuhan, 430079, China"}]},{"given":"Yuanjin","family":"Pan","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China"}]}],"member":"1968","published-online":{"date-parts":[[2018,11,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"607","DOI":"10.1007\/s00190-015-0802-8","article-title":"Accuracy and reliability of multi-GNSS real-time precise positioning: GPS, GLONASS, BeiDou, and Galileo","volume":"89","author":"Li","year":"2015","journal-title":"J. Geod."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1007\/s00190-016-0960-3","article-title":"Multi-GNSS precise point positioning (MGPPP) using raw observations","volume":"91","author":"Liu","year":"2017","journal-title":"J. Geod."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1007\/s10291-016-0545-x","article-title":"Uncovering common misconceptions in GNSS Precise Point Positioning and its future prospect","volume":"21","author":"Choy","year":"2017","journal-title":"GPS Solut."},{"key":"ref_4","unstructured":"Collins, J.P. (2008, January 28\u201330). Isolating and estimating undifferenced GPS integer ambiguities. Proceedings of the 2008 National Technical Meeting of the Institute of Navigation, San Diego, CA, USA."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1007\/s00190-007-0187-4","article-title":"Resolution of GPS carrier-phase ambiguities in Precise Point Positioning (PPP) with daily observations","volume":"82","author":"Ge","year":"2008","journal-title":"J. Geod."},{"key":"ref_6","unstructured":"Laurichesse, D., Mercier, F., and Berthias, J.P. (2009, January 22\u201325). Real time precise GPS constellation orbits and clocks estimation using zero-difference integer ambiguity fixing. Proceedings of the 2009 International Technical Meeting of the Institute of Navigation (ION GNSS 2009), Savannah, GA, USA."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"705","DOI":"10.1007\/s00190-010-0404-4","article-title":"Rapid re-convergences to ambiguity-fixed solutions in precise point positioning","volume":"84","author":"Geng","year":"2010","journal-title":"J. Geod."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1007\/s10291-010-0191-7","article-title":"Instantaneous re-initialization in real-time kinematic PPP with cycle slip fixing","volume":"16","author":"Zhang","year":"2011","journal-title":"GPS Solut."},{"key":"ref_9","unstructured":"Banville, S. (2014). Improved Convergence for GNSS Precise Point Positioning. [Ph.D. Thesis, University of New Brunswick]."},{"key":"ref_10","unstructured":"Kerner, S.M. (2018, September 30). Chinese Unicorn Team Hacks GPS at DefCon. Available online: http:\/\/www.eweek.com\/security\/chinese-unicorn-team-hacks-gps-at-defcon."},{"key":"ref_11","unstructured":"Kube, C. (2018, September 30). Russia Has Figured out How to Jam U.S. Drones in Syria, Officials Say. Available online: https:\/\/www.nbcnews.com\/news\/military\/russia-has-figured-out-how-jam-u-s-drones-syria-n863931."},{"key":"ref_12","first-page":"505","article-title":"Concepts of Comprehensive PNT and Related Key Technologies","volume":"45","author":"Yang","year":"2016","journal-title":"Acta Geod. Cartogr. Sin."},{"key":"ref_13","first-page":"24","article-title":"Assured PNT for Our Future: PTA","volume":"9","author":"Parkinson","year":"2014","journal-title":"GPS World"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Choy, S., and Harima, K. (2018). Satellite delivery of high-accuracy GNSS precise point positioning service: An overview for Australia. J. Spat. Sci., 1\u201312.","DOI":"10.1080\/14498596.2018.1427155"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"835","DOI":"10.1007\/s10291-016-0569-2","article-title":"GNSS satellite-based augmentation systems for Australia","volume":"21","author":"Choy","year":"2016","journal-title":"GPS Solut."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"351","DOI":"10.1179\/003962611X13055561708623","article-title":"A wide area real-time differential GPS prototype system in China and result analysis","volume":"43","author":"Shi","year":"2011","journal-title":"Surv. Rev."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"837","DOI":"10.3390\/rs9080837","article-title":"National BDS Augmentation Service System (NBASS) of China: Progress and Assessment","volume":"9","author":"Shi","year":"2017","journal-title":"Remote Sens."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Zhang, Y., Chen, J., Yang, S., and Chen, Q. (2017, January 23\u201325). Initial Assessment of BDS Zone Correction. Proceedings of the China Satellite Navigation Conference (CSNC 2017), Shanghai, China.","DOI":"10.1007\/978-981-10-4591-2_22"},{"key":"ref_19","unstructured":"Enge, P.K., Talbot, N.C., and San, J. (1998). Method and Reciever Using a Low Earth Orbiting Satellite Signal to Augment the Global Positioning System. (5,812,961), U.S. Patent."},{"key":"ref_20","first-page":"13","article-title":"Carrier Phase Differential Positioning augmented by LEO satellites","volume":"42","author":"Zhang","year":"2017","journal-title":"Sci. Surv. Mapp."},{"key":"ref_21","first-page":"131","article-title":"Design and Performance Analysis of LEO Satellites Enhanced COMPASS System","volume":"53","author":"Zhao","year":"2013","journal-title":"Telecommun. Eng."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1002\/j.2161-4296.2010.tb01773.x","article-title":"Analysis of Iridium Augmented GPS for floating carrier phase positioning","volume":"57","author":"Joerger","year":"2010","journal-title":"J. Inst. Navig."},{"key":"ref_23","first-page":"237","article-title":"Receiver autonomous integrity monitoring in Iridium-augmented GPS","volume":"3","author":"Tian","year":"2013","journal-title":"J. PLA Unv. Sci. Technol."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Ge, H., Li, B., Ge, M., Zang, N., Nie, L., Shen, Y., and Schuh, H. (2018). Initial Assessment of Precise Point Positioning with LEO Enhanced Global Navigation Satellite Systems (LeGNSS). Remote Sens., 10.","DOI":"10.3390\/rs10070984"},{"key":"ref_25","unstructured":"Reid, T.G.R. (2017). Orbital Diversity for Global Navigation Satellite Systems. [Ph.D. Thesis, Standford University]."},{"key":"ref_26","first-page":"1","article-title":"Progresses and Prospects in Developing Marine Geodetic Datum and Marine Navigation of China","volume":"46","author":"Yang","year":"2017","journal-title":"Acta Geod. Cartogr. Sin."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Reid, T.G.R., Neish, A.M., Walter, T.F., and Enge, P.K. (2016, January 12\u201316). Leveraging Commercial Broadband LEO Constellations for Navigation. Proceedings of the 29th International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS+ 2016), Portland, OR, USA.","DOI":"10.33012\/2016.14729"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"737","DOI":"10.1007\/s10291-015-0485-x","article-title":"Orbital representations for the next generation of satellite-based augmentation systems","volume":"20","author":"Reid","year":"2015","journal-title":"GPS Solut."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1007\/s10291-018-0719-9","article-title":"Design and validation of broadcast ephemeris for low Earth orbit satellites","volume":"22","author":"Xie","year":"2018","journal-title":"GPS Solut."},{"key":"ref_30","unstructured":"Fang, S. (2017). Model Design of Broadcast ephemerides for LEO Augmentation Navigation Satellites. [Master\u2019s Thesis, Information Engineering University]."},{"key":"ref_31","unstructured":"Rabinowitz, M. (2000). A Differential Carrier Phase Navigation System Combining GPS with LEO for Rapid Resolution of Integer Cycle Ambiguities. [Ph.D. Thesis, University of Standford]."},{"key":"ref_32","unstructured":"Satelles (2016). Satelles Time and Location White Paper, Satelles."},{"key":"ref_33","first-page":"711","article-title":"On Construction of China\u2019s Space Information Network","volume":"40","author":"Li","year":"2015","journal-title":"Geomat. Inf. Sci. Wuhan Univ."},{"key":"ref_34","first-page":"1501","article-title":"On Civil-Military Integrated Space-Based Real-Time Information Service System","volume":"42","author":"Li","year":"2017","journal-title":"Geomat. Inf. Sci. Wuhan Univ."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1007\/s00190-008-0236-7","article-title":"Deploying a Locata network to enable precise positioning in urban canyons","volume":"83","author":"Montillet","year":"2009","journal-title":"J. Geod."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1007\/s10291-014-0373-9","article-title":"Locata-based precise point positioning for kinematic maritime applications","volume":"19","author":"Jiang","year":"2015","journal-title":"GPS Solut."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1080\/10095020.2017.1325612","article-title":"The Australian approach to geospatial capabilities; positioning, earth observation, infrastructure and analytics: Issues, trends and perspectives","volume":"20","author":"Woodgate","year":"2017","journal-title":"Geo-Spat. Inf. Sci."},{"key":"ref_38","unstructured":"Kuang, D., Bertiger, W., Desai, S., and Haines, B. (2010, January 21\u201324). Precise Orbit Determination for LEO spacecraft Using GNSS Tracking Data from Multiple Antennas. Proceedings of the 23rd International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS 2010), Portland, OR, USA."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Kuang, D., Bertiger, W., Desai, S.D., Haines, B., Iijima, B., and Meehan, T. (2008, January 6\u20138). Precise orbit determination for COSMIC satellites using GPS data from two on-board antennas. Proceedings of the IEEE\/ION PLANS 2008, Monterey, CA, USA.","DOI":"10.1109\/PLANS.2008.4570030"},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Ilcev, S.D. (2018). Global Mobile Satellite Communications Applications for Maritime, Land and Aeronautical Applications, Springer.","DOI":"10.1007\/978-3-319-71858-3"},{"key":"ref_41","unstructured":"Jiao, W. (2003). Researches on the Realization of Satellite Navigation Coordinate Reference System, China Academy of Sciences. Postdoctoral Report."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"30403","DOI":"10.3390\/s151229805","article-title":"A Novel Method for Precise Onboard Real-Time Orbit Determination with a Standalone GPS Receiver","volume":"15","author":"Wang","year":"2015","journal-title":"Sensors"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1007\/s10291-018-0706-1","article-title":"Performance of the BDS3 experimental satellite passive hydrogen maser","volume":"22","author":"Wu","year":"2018","journal-title":"GPS Solut."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1007\/s10291-012-0278-4","article-title":"Short-term analysis of GNSS clocks","volume":"17","author":"Hauschild","year":"2013","journal-title":"GPS Solut."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"515","DOI":"10.1007\/s00190-013-0625-4","article-title":"Orbit and clock analysis of Compass GEO and IGSO satellites","volume":"87","author":"Steigenberger","year":"2013","journal-title":"J. Geod."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"783","DOI":"10.1007\/s10291-015-0488-7","article-title":"Analysis of BDS satellite clocks in orbit","volume":"20","author":"Wang","year":"2016","journal-title":"GPS Solut."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"434","DOI":"10.1007\/s11433-009-0049-6","article-title":"The solutions of navigation observation equations for CAPS","volume":"52","author":"Shi","year":"2009","journal-title":"Sci. China Ser. G Phys. Mech. Astron."},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Zhao, J., Li, Z., Ge, J., Wang, L., Wang, N., Zhou, K., and Yuan, H. (2018). The First Result of Relative Positioning and Velocity Estimation Based on CAPS. Sensors, 18.","DOI":"10.3390\/s18051528"},{"key":"ref_49","unstructured":"Guo, H. (2006). Study on the Analysis Theories and Algorithms of the Time and Frequency Characterization for Atomic Clocks of Navigation Satellites. [Ph.D. Thesis, Information Engineering University]."},{"key":"ref_50","unstructured":"Huang, G. (2012). Research on Algorithm of Precise Clock Offset and Quality Evaluation of GNSS Satellite Clock. [Ph.D. Thesis, Changan University]."},{"key":"ref_51","first-page":"358","article-title":"From Allan Variance to Phase Noise: A New Conversion Approach","volume":"2","author":"Zhang","year":"2011","journal-title":"J. Meas. Sci. Instrum."},{"key":"ref_52","unstructured":"RIOSDE (2008). Global Navigation Satellite System GLONASS Interface Control Document (Edition 5.1), RIOSDE."},{"key":"ref_53","unstructured":"JPO (2000). Navstar GPS Space Segment\/Navigation User Interfaces."},{"key":"ref_54","unstructured":"European Union (2010). European GNSS (Galileo) Open Service. Signal in Space. Interface Control Document, European Union."},{"key":"ref_55","unstructured":"CSNO (2017). BeiDou Navigation Satellite System Signal in Space Interface Control Document Open Service Signal B2a, CSNO. Version 1.0."},{"key":"ref_56","unstructured":"JAXA (2012). Quasi-Zenith Satellite System Navigation Service Interface Specification for QZSS, JAXA."},{"key":"ref_57","unstructured":"Locata Corporation (2014). Locata Signal Interface Control Document, Locata Corporation."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1007\/s10291-003-0055-5","article-title":"In-flight performance analysis of the CHAMP BlackJack GPS Receiver","volume":"7","author":"Montenbruck","year":"2003","journal-title":"GPS Solut."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"199","DOI":"10.1007\/s10291-012-0271-y","article-title":"(Near-)real-time orbit determination for GNSS radio occultation processing","volume":"17","author":"Montenbruck","year":"2012","journal-title":"GPS Solut."},{"key":"ref_60","unstructured":"Zhao, Y. (2011). GNSS Ionospheric Occultation Inversion and Its Application. [Ph.D. Thesis, Wuhan University]."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1007\/PL00012778","article-title":"TEQC: The Multi-Purpose Toolkit for GPS\/GLONASS Data","volume":"3","author":"Estey","year":"1999","journal-title":"GPS Solut."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"1179","DOI":"10.1007\/s10291-017-0604-y","article-title":"Enhanced orbit determination for BeiDou satellites with FengYun-3C onboard GNSS data","volume":"21","author":"Zhao","year":"2017","journal-title":"GPS Solut."},{"key":"ref_63","first-page":"73","article-title":"Real-Time Assessment of GNSS Observation Noise with Single Receivers","volume":"12","author":"Wang","year":"2013","journal-title":"J. Glob. Position. Syst."},{"key":"ref_64","unstructured":"Goebel, G. (2018, October 26). Navigation Satellites & GPS. Available online: http:\/\/www.faqs.org\/docs\/air\/ttgps.html."},{"key":"ref_65","unstructured":"Admin (2018, October 26). Decoding the Russian PARUS (COSMOS) Mavigation Satellites with the RTL-SDR. Available online: https:\/\/www.rtl-sdr.com\/decoding-russian-parus-cosmos-navigation-satellites-rtl-sdr\/."},{"key":"ref_66","unstructured":"Wang, L. (2015). Reliability Control of GNSS Carrier-Phase Integer Ambiguity Resolution. [Ph.D. Thesis, Queensland University of Technology]."},{"key":"ref_67","unstructured":"Ashby, N. (2001, January 27\u201329). Relativistic effects on SV clocks due to orbit changes and due to Earths oblateness. Proceedings of the 33rd Annual Precise Time and Time Interval (PTTI) Meeting, Long Beach, CA, USA."},{"key":"ref_68","first-page":"189","article-title":"GPS and Relativity an engineering overview","volume":"56","author":"Filegel","year":"1996","journal-title":"Aerosp. Corp."},{"key":"ref_69","doi-asserted-by":"crossref","unstructured":"Parkinson, B., Spiker, J., Axelrad, P., and Enge, P. (1996). Global Positioning System Theory and Applications, AAIA.","DOI":"10.2514\/4.866395"},{"key":"ref_70","doi-asserted-by":"crossref","unstructured":"Klobuchar, J.A. (1987). Ionospheric time-delay algorithm for single-frequency GPS users. IEEE Trans. Aerosp. Electron. Syst., 325\u2013331.","DOI":"10.1109\/TAES.1987.310829"},{"key":"ref_71","first-page":"94","article-title":"Contributions to the theory of atmospheric refraction","volume":"14","author":"Saastamoinen","year":"1973","journal-title":"Bull. G\u00e9od."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/11\/3919\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:29:35Z","timestamp":1760196575000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/11\/3919"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,11,14]]},"references-count":71,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2018,11]]}},"alternative-id":["s18113919"],"URL":"https:\/\/doi.org\/10.3390\/s18113919","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,11,14]]}}}