中国物理B ›› 2024, Vol. 33 ›› Issue (7): 70601-070601.doi: 10.1088/1674-1056/ad3dc9

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Proposal for a realtime Einstein-synchronization-defined satellite virtual clock

Chenhao Yan(严晨皓)1, Xueyi Tang(汤雪逸)1, Shiguang Wang(王时光)1,†, Lijiaoyue Meng(孟李皎悦)1, Haiyuan Sun(孙海媛)1, Yibin He(何奕彬)1, and Lijun Wang(王力军)1,2,‡   

  1. 1 Department of Precision Instrument, Tsinghua University, Beijing 100091, China;
    2 Department of Physics, Tsinghua University, Beijing 100091, China
  • 收稿日期:2024-01-07 修回日期:2024-03-18 接受日期:2024-04-12 出版日期:2024-06-18 发布日期:2024-06-20
  • 通讯作者: Shiguang Wang, Lijun Wang E-mail:wangsg@tsinghua.edu.cn;lwan@tsinghua.edu.cn
  • 基金资助:
    This work was supported by the National Key Research and Development Program of China (Grant No. 2021YFA1402100).

Proposal for a realtime Einstein-synchronization-defined satellite virtual clock

Chenhao Yan(严晨皓)1, Xueyi Tang(汤雪逸)1, Shiguang Wang(王时光)1,†, Lijiaoyue Meng(孟李皎悦)1, Haiyuan Sun(孙海媛)1, Yibin He(何奕彬)1, and Lijun Wang(王力军)1,2,‡   

  1. 1 Department of Precision Instrument, Tsinghua University, Beijing 100091, China;
    2 Department of Physics, Tsinghua University, Beijing 100091, China
  • Received:2024-01-07 Revised:2024-03-18 Accepted:2024-04-12 Online:2024-06-18 Published:2024-06-20
  • Contact: Shiguang Wang, Lijun Wang E-mail:wangsg@tsinghua.edu.cn;lwan@tsinghua.edu.cn
  • Supported by:
    This work was supported by the National Key Research and Development Program of China (Grant No. 2021YFA1402100).

摘要: Realization of high performance satellite onboard clock is vital for various positioning, navigation, and timing applications. For further improvement of the synchronization-based satellite time and frequency references, we propose a geosynchronous (GEO) satellite virtual clock concept based on ground-satellite synchronization and present a beacon transponder structure for its implementation (scheduled for launch in 2025), which does not require atomic clocks to be mounted on the satellite. Its high performance relies only on minor modifications to the existing transponder structure of GEO satellites. We carefully model the carrier phase link and analyze the factors causing link asymmetry within the special relativity. Considering that performance of such synchronization-based satellite clocks is primarily limited by the link's random phase noise, which cannot be adequately modeled, we design a closed-loop experiment based on commercial GEO satellites for pre-evaluation. This experiment aims at extracting the zero-means random part of the ground-satellite Ku-band carrier phase via a feedback loop. Ultimately, we obtain a 1$\sigma$ value of 0.633 ps (two-way link), following the Gaussian distribution. From this result, we conclude that the proposed real-time Einstein-synchronization-defined satellite virtual clock can achieve picosecond-level replication of onboard time and frequency.

关键词: Einstein synchronization, satellite virtual clock, geosynchronous satellite, carrier phase

Abstract: Realization of high performance satellite onboard clock is vital for various positioning, navigation, and timing applications. For further improvement of the synchronization-based satellite time and frequency references, we propose a geosynchronous (GEO) satellite virtual clock concept based on ground-satellite synchronization and present a beacon transponder structure for its implementation (scheduled for launch in 2025), which does not require atomic clocks to be mounted on the satellite. Its high performance relies only on minor modifications to the existing transponder structure of GEO satellites. We carefully model the carrier phase link and analyze the factors causing link asymmetry within the special relativity. Considering that performance of such synchronization-based satellite clocks is primarily limited by the link's random phase noise, which cannot be adequately modeled, we design a closed-loop experiment based on commercial GEO satellites for pre-evaluation. This experiment aims at extracting the zero-means random part of the ground-satellite Ku-band carrier phase via a feedback loop. Ultimately, we obtain a 1$\sigma$ value of 0.633 ps (two-way link), following the Gaussian distribution. From this result, we conclude that the proposed real-time Einstein-synchronization-defined satellite virtual clock can achieve picosecond-level replication of onboard time and frequency.

Key words: Einstein synchronization, satellite virtual clock, geosynchronous satellite, carrier phase

中图分类号:  (Time and frequency)

  • 06.30.Ft
84.40.Ua (Telecommunications: signal transmission and processing; communication satellites)