Results of a Long-Range Clock Synchronization Experiment

The USASRDL is conducting a feasibility study of World Wide Synchronization of Atomic Clocks (WOSAC) with an error of less than 5 μsec (l-μsec target). Original synchronization is established by flying an atomic clock from the master to the slave clocks. Synchronization is maintained by phase tracking a VLF signal controlled by the master clock. This paper gives the results of various phases of the project. Influences of the propagation medium allow VLF frequency transfer over the Atlantic with an accuracy of 2p: 10
¹¹
for a 24 hour averaging period. A synchronization experiment over 1000 miles gave an accuracy of 0.2 μsec. Further improvements by a factor of 5 of LF frequency transfer over 300 miles distances was accomplished by phase control of the radiated signal by an Atomichron.