Research on Clean-Up Technique to Improve Short-Term Stability of Rubidium Clocks

作     者：Han, Songyue Liu, Ya Xiao, Bo Wang, Jiachen Fan, Duosheng Li, Xiaohui Zhu, Feng 

作者机构：Chinese Acad Sci Natl Time Serv Ctr Measurement & Testing Technol & Instrumentat Xian Peoples R China Univ Chinese Acad Sci Beijing Peoples R China Chinese Acad Sci Key Lab Time Reference & Applicat Beijing Peoples R China Chinese Acad Sci Natl Time Serv Ctr Xian Peoples R China 

出 版 物：《IEEE INSTRUMENTATION & MEASUREMENT MAGAZINE》 (IEEE Instrum Meas Mag)

年 卷 期：2025年第28卷第1期

页      面：37-44页

核心收录：

学科分类：0808[工学-电气工程] 08[工学] 0804[工学-仪器科学与技术] 

基　　金：Special Support Project of the "West-ern Cross Team" Key Laboratory [xbzg-zdsys-202120] West Talent Training Program [XAB2019B16] West Young Scholars of the Chinese Academy of Sciences [XAB2021YN28] 

主　　题：Voltage measurement Crystals Prediction algorithms Circuit stability Rubidium Phase locked loops Standards Frequency control Clocks Testing 

摘      要：In order to improve the poor short-term stability of rubidium (Rb) clock in time transfer, this paper propose a self-adaptive dual-state control algorithm to clean up the frequency standard. Compared with control algorithms that remain in the laboratory, this algorithm has a strong engineering application background. It has the advantages of long-term stable operation, combining efficiency and simplicity. By measuring the phase difference between the Rb clock and the crystal oscillator, and calculating the predicted value to change the control voltage, a digital phase-locked loop (PLL) is formed. Based on this principle, this paper designs a digital PLL control circuit for the VCXO tracking the Rb clock. After continuous testing, the second-level stability of the Rb clock is 7.68E-13, which is improved by an order of magnitude. The enhancement greatly reduces the usage limitations of Rb clocks, offering the cost-effective of any frequency source. The crystal oscillator+ control strategy in the paper can also be applied to short-term stability improvement of other frequency sources. When the reference signal is traced to UTC (k), the VCXO can track and replicate the standard time signal.