The time reference maintained by both the punctual laboratory and the global navigation satellite system (GNSS) is traced to UTC (k) through different traceability links, with k being the laboratory code.At present, the mainstream traceability methods include optical fiber time transfer, Two-way satellite time reference and GNSS common view time transfer.The closed-loop clock difference model is constructed for different tracing links, and the clock difference of each tracing link is corrected by indirect adjustment, which eliminates the errors of system difference and period term in different links, and improves the accuracy of time transmission.The algorithm is verified by using the measured clock difference data of 8 independent and different tracing links in 5 time-frequency stations.The results show that, due to the influence of uneliminated spatial errors, both satellite bidirectional time transfer and GNSS co-view time transfer have obvious period terms under long baseline conditions.By correcting the adjustment of the tracing link, the problem of unclosed tracing clock difference is eliminated.The GNSS common-view time transfer noise is decreased from 0.43 ns to 0.25 ns, the satellite bidirectional time transfer noise is decreased from 0.21 ns to 0.14ns, and the optical fiber time transfer noise is decreased from 0.18 ns to 0.12 ns by calculating the residual from the quadratic polynomial fitting of the clock difference.By improving the time transmission accuracy of each tracing link, the service capability of each time reference is effectively improved.
time referencetime and frequency transfercommon viewresidual erroradjustment
万方数据
维普
