Satellite constellation time-frequency synchronization system and method based on bidirectional coherent inter-satellite link

Abstract

The application discloses a constellation time-frequency synchronization system and method based on a bidirectional coherent inter-satellite link, and relates to the technical field of satellite communication. The system comprises a bidirectional coherent inter-satellite link module, a time stamp generation and analysis module, a bidirectional time measurement module, a carrier phase measurement module, a Doppler compensation module, a time-frequency joint estimation module, a space-borne atomic clock taming module and a constellation synchronization control module. The system adopts bidirectional coherent transmission combined with a four-time stamp method to eliminate propagation time delay error, obtains high-precision phase difference and frequency offset through carrier phase measurement, corrects the influence of low-orbit satellite movement through two-stage Doppler compensation, realizes time-frequency joint estimation by fusing multi-source observation through extended Kalman filtering, and completes full constellation synchronization distribution through a three-level topology of master clock satellites, regional synchronization satellites and service satellites, and has link redundancy and interruption maintaining capability. The application can realize sub-nanosecond time synchronization and high-precision frequency synchronization, and is suitable for large-scale low-orbit satellite constellation autonomous time-frequency synchronization.