Progress on Sapphire Hydrogen Maser for Beidou Navigation System
Active hydrogen maser is one of the most important equipments for the Beidou Navigation system. The stability of active hydrogen maser does influence the synchronize accuracy of time and frequency between the satellites and the ground devices. In order to
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Progress on Sapphire Hydrogen Maser for Beidou Navigation System Tiezhong Zhou, Qiong Wu, Jian Huang and Lianshan Gao
Abstract Active hydrogen maser is one of the most important equipments for the Beidou Navigation system. The stability of active hydrogen maser does influence the synchronize accuracy of time and frequency between the satellites and the ground devices. In order to improve the stability of Sapphire Hydrogen Maser, we had done several improvements on the physical package and electrical package, which include magnetic shield improvements, developing a method to probe the hydrogen atom beam, getter pump improvement and cavity auto-turning system researching. The factor of magnetic shield has been improved to above 105. We had researched several kinds of getter materials which can improve the lifetime of physical package. We had designed a new form of getter pump, which make the volume of physical package smaller than ever. The stability of the maser after improvement can get 3.1 9 10-13 @ 1 s, 2.9 9 10-15 @ 1 day.
Keywords Hydrogen maser Magnetic shield Improvement Beam controlling Frequency stability
33.1 Introduction To ensure normal operation of the Beidou Compass Navigation Satellite System [1] of China which is under construction, the ground stations must conduct continual detection and control over the space satellite system. In order to maintain Beidou time system, master control station, injection station and monitoring T. Zhou (&) Beijing University of Aeronautics and Astronautics, Beijing 100191, China e-mail: [email protected] T. Zhou Q. Wu J. Huang L. Gao Beijing Institute of Radio Metrology and Measurement, Beijing 100854, China
J. Sun et al. (eds.), China Satellite Navigation Conference (CSNC) 2013 Proceedings, Lecture Notes in Electrical Engineering 245, DOI: 10.1007/978-3-642-37407-4_33, Ó Springer-Verlag Berlin Heidelberg 2013
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station jointly track Beidou Satellite to calculate data such as satellite ephemeris, satellite clock stability, and drifting, input navigation message and control instruction, detect and control over the ‘‘health’’ status of the satellite. The accomplishment of above tasks is based on the accurate atomic clock system on the ground. During the synchronizing process between ground clock and satellite clock, the system time base on central control station is regarded as the ideal clock, and it has to be made up of large amount of reliable hydrogen clocks and caesium clocks. Moreover, the strict synchronization between local ground stations for orbit calculation and ground stations for time synchronization also rely heavily on the highly stable and reliable hydrogen clocks and caesium clocks on the ground. Therefore, highly reliable and stable active hydrogen maser is basic equipment of ground time frequency system of Beidou System and its performance indicators determines the generation and maintenance of the time of Beidou System, and directly affects the timing accuracy and navigation positioning accuracy of Be
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