{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:08:00Z","timestamp":1760242080445,"version":"build-2065373602"},"reference-count":21,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2018,11,30]],"date-time":"2018-11-30T00:00:00Z","timestamp":1543536000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Hubei Province Natural Science Outstanding Youth Foundation","award":["2018CFA052"],"award-info":[{"award-number":["2018CFA052"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The BeiDou system satellites may be unhealthy due to many reasons, affecting system performance in different ways. Therefore, it is important to analyze the causes and characteristics of the satellites\u2019 unhealthy states. In this study, these states are classified into five types based on the broadcast ephemeris. Three criteria are presented, based on which a general classification method is proposed. Data from July 2017 to June 2018 are analyzed to validate the method, from which we know that the average unhealthy duration due to satellite maneuvers is much longer than the duration of unhealthy states related to satellite orbit or clock anomalies, and the other unhealthy states may be caused by inbound or outbound satellites. Statistics show that most of the time, the number of unhealthy satellites is no more than two and the average positioning accuracy in the service area will decrease by no more than 0.75 and 1.2 meters when one or two BDS satellites are unhealthy, respectively.<\/jats:p>","DOI":"10.3390\/s18124196","type":"journal-article","created":{"date-parts":[[2018,11,30]],"date-time":"2018-11-30T12:13:17Z","timestamp":1543579997000},"page":"4196","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["BeiDou Satellite Unhealthy States and the Impact on System Performance"],"prefix":"10.3390","volume":"18","author":[{"given":"Caibo","family":"Hu","sequence":"first","affiliation":[{"name":"GNSS Research Center, Wuhan University, Wuhan 430072, China"},{"name":"Beijing Satellite Navigation Center, Beijing 100094, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chuang","family":"Shi","sequence":"additional","affiliation":[{"name":"GNSS Research Center, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jinping","family":"Chen","sequence":"additional","affiliation":[{"name":"GNSS Research Center, Wuhan University, Wuhan 430072, China"},{"name":"Beijing Satellite Navigation Center, Beijing 100094, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yidong","family":"Lou","sequence":"additional","affiliation":[{"name":"GNSS Research Center, Wuhan University, Wuhan 430072, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8139-3584","authenticated-orcid":false,"given":"Fei","family":"Wang","sequence":"additional","affiliation":[{"name":"Beijing Satellite Navigation Center, Beijing 100094, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,11,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"734","DOI":"10.2514\/2.4447","article-title":"Simple approach to east-west station keeping of geosynchronous spacecraft","volume":"22","author":"No","year":"1999","journal-title":"J. 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