期刊名称：International Journal of Innovative Research in Science, Engineering and Technology
印刷版ISSN：2347-6710
电子版ISSN：2319-8753
出版年度：2017
卷号：6
期号：5
页码：7301
DOI：10.15680/IJIRSET.2017.0605005
出版社：S&S Publications
摘要：The stability and accuracy of the on-board clocks play an important role in the performance of anynavigation system. The navigation user’s position is determined by measuring the time of travel of the signalsbroadcasted from satellites to the users. The error in the measurement of time interval effects the user position.Therefore the on-board clock behaviour has to be continuously monitored and any malfunctioning has to be noticedimmediately to improve the capability of the timing system for accurate positioning of the user.Each IRNSS satellite carries three Rubidium Atomic Frequency Standards (RAFS), one primary and two redundantclocks (Hot redundant & Cold redundant). The stability of these satellite clocks can change with time due to severalfactors, such as environmental effects and aging. Hence, it is important to characterize the time-varying clockbehaviour. An algorithm was developed to measure the clock inaccuracies in terms of stability and detection ofanomalies. This paper provides In-Orbit clock performance results of IRNSS RAFS using both conventionalOverlapping Allan Deviation (OADEV) and Dynamic Allan Deviation (DADEV). All IRNSS satellites meet thedesired stability specifications of 5.0E-14 at 10000 secs hence ensuring the user equivalent error due to clock noise isbetter than 0.4 ns
关键词：Satellite clock; Allan variance; Atomic Frequency Standard; Clock characterization.
