A First Exploration of Joint Time Keeping with Hydrogen and Cesium Clocks

Hydrogen clocks and caesium clocks are two different types of frequency providers and statistics experts in time and frequency domains have reached a consensus on their short-time and long-term stability characters. With the improvement of technology the hydrogen clock has increased its long-term stability in recent years. According to our analyses of data obtained from the two newly imported US hydrogen clocks (Sigma τ) at National Time Service Center (NTSC) of Chinese Academy of Sciences, the frequency stability of the hydrogen clocks in different sampling intervals are quantitatively described and the hydrogen clocks are compared with the cesium clocks regarding performance. In the light of their merits and deficiencies in performance we outline a scheme of joint time keeping with the two types of clocks.