Over the past 3 years a frequency standard of very high precision has been installed in Canada. It is composed of equipment located in three different laboratories in Ottawa, Ontario, but separated by a few miles. Intercomparison of frequency between these laboratories, which is done by sending signals over telephone lines and related techniques, is briefly described. Results indicate frequency stability of about 2:1010 over short and long periods. Absolute frequency is determined from astronomical observations. International inter-comparison is carried out by phase measurement of standard frequency and by observations of time signals; some of the results are presented.
Characterization of the absolute frequency stability of an individual reference cavity
