The Time & Frequency Research Center is the research department of Shanghai Astronomical Observatory dedicated to the theory and technology of time and frequency and atomic frequency standards. Time and frequency technology and atomic clock technology play an indispensable role in applications including nuclear physics, communications, navigation, surveying and mapping. The Center comprises research groups developing active hydrogen atomic clocks, passive hydrogen atomic clocks, and time and frequency technology.

Shanghai Astronomical Observatory is among the earliest institutions in China to conduct time and frequency research. As early as 1884, the Bund Observatory in Shanghai provided time signals by dropping a time ball; in 1914, Xujiahui Observatory began transmitting radio time signals; in 1939, it joined the Bureau International de l’Heure’s international cooperation on Universal Time; in 1964, Shanghai Astronomical Observatory’s Universal Time research reached an advanced international level. From 1958 to 1981, the Observatory broadcast China’s standard time and frequency signals BPV and XSG via shortwave radio. In 1978, it established China’s first local atomic time scale.

On September 30, 1969, Premier Zhou Enlai met with the Observatory’s scientific and technical personnel and called for an independent time and frequency system for China. The Observatory subsequently launched the “930” Project, carrying out research on ammonia molecular clocks, large cesium clocks, active hydrogen atomic clocks, passive hydrogen atomic clocks, and the establishment of a local atomic time scale. The Observatory is currently the only institution in China capable of producing practical hydrogen atomic clocks in batches, and is a principal developer and builder of time and frequency systems, including hydrogen atomic frequency standards, for major national projects. To date, more than 100 hydrogen clocks have been produced and put into use, and key time and frequency systems for major national projects have been developed and established. The performance of the Observatory’s active hydrogen clocks meets the application requirements of most engineering fields in China. During the Eleventh Five-Year Plan period, with support from relevant national authorities, the technical performance and reliability of its active hydrogen clocks improved significantly: stability reached 2 × 10⁻¹⁵ over one day, with a mean time between failures (MTBF) greater than 5,000 hours. Its passive hydrogen clocks meet the technical requirements of major national projects, with stability reaching 8 × 10⁻¹⁵ over one day. The time and frequency systems built for major national projects, including hydrogen atomic frequency standards, offer performance that is leading domestically and advanced internationally.

Director: SHUAI Tao

Deputy Director: XIE Yonghui

Contact: 021-34775600 (wangnan@shao.ac.cn)