Ground-based demonstration of the European Laser Timing (ELT) experiment.

The development of techniques for the comparison of distant clocks and for the distribution of stable and accurate time scales has important applications in metrology and fundamental physics research. Additionally, the rapid progress of frequency standards in the optical domain is presently demanding additional efforts for improving the performances of existing time and frequency transfer links. Present clock comparison systems in the microwave domain are based on GPS and two-way satellite time and frequency transfer (TWSTFT).