GNSS+ VCXO +Atomic Clock: Applied to Communication and Navigation Fusion Satellites' Time and Frequency System

VCXO has low cost and good short stability characteristics, but the long-term stability index is poor, which cannot guarantee the frequency accuracy of communication and navigation satellites in a long time. This paper presents a highly continuous, highly stable, integrated time-frequency system: GNSS+ VCXO+ Atomic clock, which is used to generate satellite time and frequency reference. This time-frequency scheme not only takes into account the long-term stability characteristics of the atomic clock, but also uses GNSS to tame the VCXO with excellent short-term stability and low cost. The design results show that the comprehensive index of the time-frequency system is better, the accuracy of the atomic clock (working clock) is better than 3.80E-10, the stability is better than 9.18E-14/1000s, the accuracy of the GNSS+ VCXO (hot standby clock) is better than 5.0E-11, which can be applied to the communication and navigation fusion satellite in engineering.