Proposal for a Novel Remote Synchronization System for the On-Board Crystal Oscillator of the Quasi-Zenith Satellite System

A remote synchronization system for the on-board crystal oscillator (RESSOX) of the QZSS is proposed. Aimed at offering an alternative architecture for the classic GPS time-keeping system (TKS), the proposed system consists of a synchronization framework where an ultrastable atomic clock, localized at the ground station, is kept synchronized to a second time reference, a voltage-controlled crystal oscillator (VCXO), on-board the QZSS satellite. Based on orbit calculations and delay predictions, feedback and feed-forward control guarantee the correct synchronization of the on-board time reference and the ground-station atomic clock. Compared with the classic GPS TKS, the RESSOX scheme offers several advantages in terms of accuracy, cost, weight, and power consumption. An extensive explanation of this novel design is presented. Differences and advantages of the proposed system are compared with the classic atomic clock scheme.