A new steering strategy for UTC(NTSC) based on hydrogen maser

Abstract

National Time Service Center, Chinese Academy of Sciences(NTSC) has taken the charge of the national standard time UTC(NTSC). The difference between UTC(NTSC) and UTC has not exceeded ±20ns ever since 2012, which is notable achievements in high precision time-keeping. But short-term(<5 d) stability of UTC(NTSC) is poor, and the robustness and accuracy of UTC(NTSC) is also what we want to improve, therefore a hydrogen maser is used as master clock instead of a cesium clock, Hydrogen maser clocks usually exhibits apparent frequency drift. To handle this problem, we compared performance of hydrogen maser clocks with that of cesium clocks, and proposed a new steering algorithm, which is testified with data in our Time-keeping laboratory. Result shows that the time difference between UTC(NTSC) and UTC was always less than 10ns, and local time scale UTC(NTSC) has better short-term frequency stability during the time between April 2015 and April 2016.