Research On The Method Of Frequency Steering Of Master Clock Based On UTCr

With the development of productivity and the progress of science and technology, the time science has been applied to all fields of human activity, science experiments and national construction. Communication, position, navigation and many other activities heavily rely on high-precision time service. The requirements of accuracy of time are yearly increasing.International Atomic Time(TAI) is the time scale calculated by using the atomic clock comparison data of globally distributed time-keeping laboratories, the calculation period is about 30 days. It is a hysteretic time scale. Coordinated Universal Time(UTC), published by Bureau International des Poids et Measures(BIPM), is the "paper time" which is obtained through comprehensive calculation of TAI and Universal Time and is the international standard followed by national time service. Since BIPM began to release UTC, there has been a certain time lagging, the lagging time is about 15 to 45 days. So UTC can not be applied to nearly real-time applications.BIPM proposed rapid UTC(UTCr) in July 2013.Compared with UTC, the lagging time of UTCr is much shorter than that of UTC, about 4 to 10 days. UTCr can provide more nearly real-time reference for master clock frequency steering of time-keeping laboratories which maintain a local coordinated universal time UTC(k). As a standard time, UTC(k) is a local realization of UTC. In order to obtain accurate time and frequency signals, time-keeping laboratories all adopt master clock frequency steering method for the purpose of decreasing the deviation between UTC(k) and UTC.The goal of steering is to keep high frequency accuracy and frequency stability of UTC(k) related to UTC.In the study of master clock frequency steering method, the traditional clock rate prediction method is based on the atomic clock rate of last month related to TAI published by the BIPM monthly. This method presents a hysteretic nature. Furthermore, because of the influence of noise and its own characteristics, it is difficult to predict the clock rate in real-time, hence, to get a more stable and more accurate UTC(k) is impossible.The thesis adopts the research method of combining theory with practice, studies the master clock frequency steering method based on UTCr and realizes steering experiment under the conditions of time and frequency standard laboratory of the National Time Service Center. The content of this thesis involves the preprocessing method of atomic clock comparison data, the algorithm of reference atomic time and so on.It focuses on the preprocessing method of UTCr, the dynamic prediction method of atomic clock rate based on UTCr and the algorithm of reference atomic time scale based on UTCr. The research work of this thesis mainly includes:(1) The preprocessing method of UTCr. Smooth the data of UTCr -UTC(k)by the method of Vondark filtering. The root mean square(RMS) is considered as the standard to evaluate the time accuracy, so as to determine the optimal smoothing factor.(2) On the basis of traditional rate prediction method, the thesis studies the dynamic rate prediction method of atomic clock based on UTCr. Additionally, it predicts the atomic clock rate by using different prediction methods for historical clock comparison data from January 2014 to August 2014.Compare the forecasting accuracy of the different methods with the standard rate published by BIPM. Thus we can obtain the conclusion that dynamic prediction method of atomic clock rate based on UTCr is more superior to the traditional prediction method, which is used to improve the accuracy of the clock rate prediction.(3) On the basis of ALGOS algorithm, the thesis studies the reference atomic time algorithm based on UTCr. Calculate the reference atomic time by the above method and the traditional ALGOS algorithm respectively and compare the accuracy and stability of frequency of the difference of reference atomic time and UTC. Thus we can obtain the conclusion that the reference atomic time algorithm based on UTCr is more effective to the traditional reference atomic time algorithm, which is used to provide a more nearly real-time and reliable reference for frequency steering.The thesis focuses on the research of the preprocessing method of UTCr, the dynamic prediction method of atomic clock rate based on UTCr and the algorithm of reference atomic time scale based on UTCr. The historical atomic clock comparison data is used in the simulation of the master clock frequency steering method and the feasibility of the method has been proved. Under the conditions of time and frequency standard laboratory of the National Time Service Center, hardware test platform has been set up and the system software has been compiled to realize the steering of the output frequency signal of UTC(k). The verification system software continuously runs in the hardware test platform in real-time from February 2015. The results are consistent with the simulation results. According to the mentioned above, the master clock frequency steering method discussed in the thesis is feasible and effective, is superior to the traditional method and is helpful for getting a more stable and more accurate UTC(k).