Abstract
In the Global Navigation Satellite System (GNSS) community, the Quasi-Zenith Satellite System (QZSS) is an augmentation system for users in the Asia-Pacific region. However, the characteristics and performance of four QZSS satellite clocks in a long-term scale are unknown at present. However, it is crucial to the positioning, navigation and timing (PNT) services of users, especially in Asia-Pacific region. In this study, the characteristics and performance variation of four QZSS satellite clocks, which including the phase, frequency, frequency drift, fitting residuals, frequency accuracy, periodic terms, frequency stability and short-term clock prediction, are revealed in detail for the first time based on the precise satellite clock offset products of nearly 1000 days. The important contributions are as follows: (1) It is detected that the times of phase and frequency jump are 2.25 and 1.5 for every QZSS satellite clock in one year. The magnitude of the frequency drift is about 10−18. The periodic oscillation of frequency drift of J01 and J02 satellite clocks is found. The clock offset model precision of QZSS is 0.33 ns. (2) The two main periods of QZSS satellite clock are 24 and 12 hours, which is the influence of the satellite orbit; (3) The frequency stability of 100, 1000 and 10,000 s are 1.98 × 10−13, 6.59 × 10−14 and 5.39 × 10−14 for QZSS satellite clock, respectively. The visible “bump” is found at about 400 s for J02 and J03 satellite clocks. The short-term clock prediction accuracy of is 0.12 ns. This study provides a reference for the state monitoring and performance variation of the QZSS satellite clock.
Highlights
The performance of the atomic clock equipped on the navigation satellite plays a key role in the positioning, navigation and timing (PNT) services
We focus on the characteristics and performance evaluation of four Quasi-Zenith Satellite System (QZSS) onboard satellite clocks
The onboard satellite clock is the key equipment of the QZSS
Summary
The performance of the atomic clock equipped on the navigation satellite plays a key role in the positioning, navigation and timing (PNT) services. Hauschild et al [9] analyzed the short-term stability of the J01 satellite clock by using the Allan deviations, and the frequency stability value when the integration time is 1, 10, 100, 1000 and 10,000 s are obtained, respectively. The satellite clock performance index, which including the phase, frequency, frequency drift, fitting residuals, frequency accuracy, periodic terms, frequency stability and short-term clock prediction were presented and analyzed in detail.
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