關鍵詞:原子鐘 頻率穩定性 置信區間 等效自由度Computation of the Time-domain Frequency Stability of Atomic ClocksGUO Hai-rong, GUO Shu-ren, JIAO Wen-hai,ZHOU Hong-wei1. Institute of Surveying and Mapping, Information Engineering University, Zhengzhou, Henan Province 450052; 2. Beijing Aerospace Control Center, Beijing 100094; 3. Beijing Institute of Tracking and Telecommunications Technology, Beijing 100094Abstract:Calculation formulas for various variances are first given in this paper and they are used in analysis of timedomain frequency stability. Then, the characteristics of the variances are analyzed together with a summary of their applications. Comparisons and analysis show the following： （ 1 ） Allan variance is the most common method for analyzing time-domain frequency stability of atomic clocks, but white PM and flicker PM cannot be separated ; （2） Modified Allan variance can separate the two PM noises by phase average operation; （3） Time variance and its total estimator are mainly used for analyzing the time fluctuations of an atomic clock, that is to say, it is mainly used for analyzing PM noises; （4） Hadamard variance provides the preferred statistics in situations when the frequency drift is above the very low frequency noise effect.[著者文摘]
Key words:Atomic Clock; Frequency Stability; Confidence Interval; Equivalent Degrees of Freedom