Study on time scale algorithm of hydrogen maser based on minimum error theory

With the rapid development of science and technology, the demand for time and time signal is getting higher and higher by users in various fields. Most of the world's time laboratories use high performance cesium clocks and hydrogen masers for timekeeping in order to ensure the accuracy and stability of their atomic time scale. The hydrogen maser has excellent stability. However, the hydrogen maser has frequency drift, and the inaccurate deduction of the frequency drift of the maser will affect the accuracy of the atomic time calculation directly. Therefore, in this paper, a method based on the minimum error theory is used to estimate the frequency drift parameter of masers in a certain time interval. Three hydrogen masers operated in NTSC (National Time Service Center) are used to determine the frequency drift parameter. After removing hydrogen maser frequency drift, we use exponential filtering method to calculate the time scale based on hydrogen masers. At the same time, according to the frequency drift parameters of the hydrogen masers published in BIPM Circular T, the frequency drift is deducted and the time scale is calculated. The former is a dynamic estimation of the drift and the initial values is set to the values which come from Circular T. Then the comparative analysis is made at the end. The results show that the method based on minimum error theory can accurately estimate the drift of hydrogen maser, and the accuracy of this time scale is significantly higher than another atomic time scale, and the absolute value of maximum deviation with TA(NTSC) is 3.51ns.