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Mathematical Problems in Engineering
Volume 2013, Article ID 136301, 7 pages
http://dx.doi.org/10.1155/2013/136301
Research Article

Improvement and Simulation of an Autonomous Time Synchronization Algorithm for a Layered Satellite Constellation

1Department of Electronics and Communication Engineering, Changsha University, Changsha 410022, China
2Key Laboratory of Precision Navigation and Timing Technology, Chinese Academy of Sciences, Xi’an 710600, China
3National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, China

Received 1 September 2013; Revised 5 November 2013; Accepted 14 November 2013

Academic Editor: Cao Su-Qun

Copyright © 2013 Feijiang Huang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Autonomous time synchronization for satellite constellations is a key technology to establish a constellation system time without the use of a ground station. The characteristics of satellite visibility time for layered satellite constellations containing geostationary earth orbit (GEO), inclined geosynchronous orbit (IGSO), and medium earth orbit (MEO) satellites are simulated by establishing a visible satellite model. Based on the satellite visible simulation results for a layered constellation, this study investigates the autonomous time synchronization algorithm that corresponds to the layered constellation structure, analyzes the main error of the time synchronization algorithm, and proposes methods to improve the characteristics of satellite movement in the constellation. This study uses an improved two-way time synchronization algorithm for autonomous time synchronization in the GEO-MEO satellite layer of a layered satellite constellation. The simulation results show that in a condition with simulation errors, the time synchronization precision of this improved algorithm can be controlled within 5 ns and used in high-precision autonomous time synchronization between layered satellite constellations.