The uncertainty in the realization and dissemination of the SI second is determined by the characteristics of three major components: (1) the primary frequency standards themselves, (2) the time scale fly wheels that provide a continuously present frequency reference, and (3) the frequency transfer systems. Currently these three systems contribute at approximately equal levels at the mid 10-16 range over 20 to 30 days of averaging time to the practical delivery of the SI second to the most demanding users. Any significant improvement in one system requires similar improvements in the other two systems in order for users to see the full benefits.
Citation: Review of Scientific Instruments
Pub Type: Journals
atomic frequency standards, time scales, time and frequency transfer