A Method for Establishing Elastic Time-Frequency Reference for Navigation Constellation

The time synchronization accuracy of navigation constellations determines the performance of navigation positioning and timing, while the reliability of satellite time and frequency determines the safety of system navigation positioning and timing services. In order to further improve the accuracy of navigation con-stellation time and frequency and the reliability of constellation time and frequency system operation, the article proposes the establishment and maintenance technology of navigation constellation elastic time and frequency reference, pro-vides the basic concept of navigation constellation elastic time and frequency reference establishment and maintenance technology, and describes the frame-work of navigation satellite and constellation elastic time and frequency reference composition. Starting from three aspects of the elastic combination of spaceborne time clock sources, the elastic measurement of time-frequency transmission link, and the elastic International Atomic Time algorithm, this paper focuses on the noise characteristics of the atomic clock taking into account the environmental impact, the clock difference correction model adapted to different atomic clocks, and the elastic integrated International Atomic Time algorithm. The analysis of the impact of random noise and colored noise on time frequency transmission links shows that if we want to achieve frequency signal transmission with a 10000 s stability better than 1 × 10^–14, the observation noise of the link should be less than 0.05 ns, and the colored noise of the link should be less than 0.1 ns. Finally, the article conducted simulation analysis on typical scenarios of navigation satellite elastic time-frequency reference operation based on the data of the Beidou-3 satellite in orbit atomic clock. Under the working conditions of a clock group consisting of only 9 satellite hydrogen clocks, the 2-h clock deviation prediction error is less than 0.05 ns, and the 24-h clock deviation prediction error is less than 0.1 ns. As the failure rate de-creases, the error of clock deviation prediction will further decrease, effectively improving the accuracy of satellite clock deviation prediction.