Ultra-Short-Term Stability Analysis of GNSS Clocks

Abstract

Nowadays, the GNSS applications have been developed not only with high requirement on the positioning accuracy, but also with high frequency and high dynamic observations. In the high frequency and high dynamic application like GNSS radio occultation, single receiver observations are normally used, and the GNSS clocks may became an important error source as differential method cannot be used. In this paper, the ultra-short-term stability of the GNSS clocks are investigated with 20 Hz dual-frequency observations, the receiver clock errors are removed with observation differential between satellites, and first order ionosphere delays are eliminated with ionosphere-free combination. In order to avoid the second order ionosphere delay, ionosphere peace period observations are used for analysis, and the troposphere delay are estimated with mapping function. Finally, the ultra-short-term stability of different atomic clocks onboard GPS and Beidou satellites are analyzed with Hadamard Deviation. The results show that the clock errors stability of 0.05 s in GPS system and Beidou system can reach up to a 10⁻¹⁰ degree, and the stability of 1 s interval reach up to a 10⁻¹¹ degree. Hence, it can be concluded that the Beidou satellite clocks have the equivalent performance compared with GPS satellite clocks on ultra-short-term stability, and the accuracy of the Beidou satellite-based radio occultation will be able to achieve the same level as GPS based radio occultation.