Uncertainty of a frequency comparison with distributed dead time and measurement interval offset

摘要

A theory is presented for estimating the uncertainty of a frequency comparison in the presence of distributed dead time or measurement interval offset using an extension of the method of Douglas and Boulanger (1997 Proc. 11th European Frequency and Time Forum pp 345-9). The uncertainties due to the distributed dead time and lumped dead time with mixed power law noise type are calculated and compared. It is shown that the use of distributed measurements of frequencies can greatly reduce the uncertainty as compared with that of lumped measurements. When a measurement interval offset is present, two different methods are possible for the frequency estimation and uncertainty evaluation. We compare and discuss the different results for the different methods.