Research On Joint Time-keeping Algorithm Based On Virtual Clocks

With the development of social science and technology,the current communication,finance,power,transportation and other industries need high-precision time scale to maintain the time synchronization of the whole system.The high-precision time reference mainly depends on the clock group of the time-keeping laboratory,which is generated by the time-keeping.Therefore,the study of time-keeping has practical needs and significance.At present,the clock group of the time keeping laboratory is mainly composed of hydrogen masers and cesium clocks.The time keeping laboratory generally has one-way satellite timing or satellite common view traceability link.Through the traceability link,the clock difference between the remote high standard time scale and the local time can be obtained,so the remote atomic clock affected by the traceability link can be regarded as a local "virtual clock" participating in the time keeping.This thesis focuses on the research of the hydrogen masers and cesium clocks joint time keeping algorithm based on the remote virtual clock,and achieves the following research results:First of all,the characteristics of clocks are analyzed,the clock difference models of hydrogen masers and cesium clocks are built,the main noise characteristics and frequency drift characteristics of hydrogen masers and cesium clocks are discussed,and the method of calibrating frequency drift is given.Based on the characteristics of clocks,hydrogen masers and cesium clocks are generated by simulation.The stability and frequency drift characteristics of the simulation clock meet the requirements of the real clock.Then the principle of timescale algorithm is derived by theoretical formula.Then,based on the local autonomous time-keeping scene of the hydrogen masers cesium clocks hybrid clock group,aiming at the problem that the frequency drifts of hydrogen masers are large,which affects the long-term stability of the generation time scale,an autonomous time-keeping algorithm of the hydrogen masers cesium clocks hybrid clock based on the frequency drift calibration is proposed,and two kinds of time-scale algorithms for the calibration of the hydrogen masers frequency drift generation are given: the time-scale algorithm based on the frequency drift deduction and the time-scale algorithm based on the multi-dimensional weighting.The two algorithms calibrate frequency drifts of hydrogen masers by directly deducting the frequency drifts of hydrogen masers from the clock difference data,decomposing and weighting the clock difference in multi dimensions,and allocating small weight to the frequency drift,reducing the frequency drift of the generated time scale,and improving the long-term stability of the generated time scale.The advantages of the multi-dimensional weighting algorithm are illustrated by the theoretical analysis and experimental results.Finally,on the basis of the previous research,the clock difference of local maser and remote high standard time are obtained by adding satellite one-way time service and satellite common view traceability link,and the remote virtual clock model is constructed.The remote virtual clock participates in the local clock group for time keeping.With the help of the characteristics of small frequency offset,small frequency drift,high long-term stability and accuracy,the long-term stability of local time scale is improved.The research results of this thesis can be applied to the autonomous time keeping scenario with hydrogen masers and cesium clocks in local clock group,which can improve the long-term stability of the local time scale;and can be applied to the joint time keeping scenario of hydrogen masers and cesium clocks with one-way satellite timing or satellite common view traceability link,which can improve the long-term stability of the local time scale.