Research on Remote Synchronization System for Onboard Crystal Oscillators of Quasi-Zenith Satellites

Space Technology Group, Energy Technology Research Institute, AIST
and
Frequency Measurement Systems Section, Time and Frequency Division, Metrology Institute of Japan, AIST

---

A new timekeeping method for the quasi-zenith satellite (QZS) system that is Japanese local positioning system is proposed. The remote synchronization system for an onboard crystal oscillator (RESSOX) of the QZS functions by keeping the satellite clock with uplinking time information. First, the concept of the RESSOX is introduced. Then, the required apparatuses for the RESSOX are considered. Finally, some experimental results on the ground are demonstrated indicating that the goal of synchronization between the ground station and the QZS to within 10 ns is feasible.

What is the RESSOX ?

RESSOX: Remote Synchronization System for Onboard Crystal Oscillators

Ground Test Bed and Experiment Results

-The VCXO is controlled to within 0.5 ns eventually.
-The Allan deviation at 40,000 s is 2 x 10^-15.

Comparison with atomic clocks

Note that even if onboard atomic clocks are used, the VCXO is also required. In contrast, in the case of the RESSOX, only the VCXO is required.

Last Update: Aug. 28, 2006