Signal frequency measurement by rational approximations

Abstract

An alternative method of signal frequency measurement based on the direct frequency comparison principle is presented. Based on a model of its measuring process, it is shown that the resulting measurement is a rational approximation to the true value, and that this approximation has a higher accuracy than approximations by systematic fractions. The properties of mediant fractions are used in the measurement model for two given fractions. The results obtained from the simulation of the measurement model are presented. It is shown that the accuracy of frequency measurement that can be obtained with this method is equivalent to the repeatability of the atomic standard of frequency and time. This method can be implemented in a short time using low cost hardware. © 2008 Elsevier Ltd. All rights reserved.