Scientists from the research group of Time and Frequency Measurement, National Time Service Center(NTSC), Chinese Academy of Sciences(CAS) recently invented an new method autonomous time synchronization method of time unified system without traceability data.
Time unified system is a necessary electronic equipment system with synchronized time and frequency in navigation system, aerospace, communication and other fields. It needs to trace to higher precision reference time. However, due to various faults or abnormalities in the traceability comparison link, the traceability reference will be unavailable.
Scientists proposed a time autonomous maintenance method with small step-by-step adjustment of the control strategy based on Autoregressive high-precision time difference prediction after a large number of experiments. This method not only ensures high-precision autonomous holding ability of the system when there the traceability reference data is interrupted. At the same time the sudden change of signal phase and frequency is avoided. It realizes the stable and continuous transition of time and frequency after traceability reference recovery, which ensures the accuracy of the time system and improves its availability.
The invention can be applied to a high-precision time frequency system based on atomic clocks. The one-day synchronization accuracy is less than 2ns without traceability reference data. The system with this technology can continuously and effectively operate up to five years.
Parts results published on the Journal of Sensors&Transducers. (Research on Dynamic Steering Method of Atomic Clock Based on Residual Correction). (Vol.238:https://www.sensorsportal.com/HTML/DIGEST/Digest_Nov_2019.htm).
Figure 1: time difference data without autonomous time synchronization method (twenty-three hours)(Image by NTSC)
Figure 2: time difference data with autonomous time synchronization method (twenty-three hours)(Image by NTSC)
National Time Service Center, Chinese Academy of Sciences