Frequency Instability Measurement Device Based on the Pulse Coincidence Principle
Context. The task of rapid and accurate measurement of the dynamic characteristics of modern signal sources with a frequency output, in particular, the short-time frequency instability function, calls for refining measurement techniques with account of the requirement to improve their metrological characteristics, reduce test time, and automate measurements by using information-and-measurement systems. Objective. The goal of the work is to develop a method of measuring the short-time frequency instability function using the principle of pulse packet coincidence and experimental investigation of measurement devices based on this principle. Method. A method was developed for measuring the short-time frequency instability function based on the principle of packet coincidence of regular independent pulse trains. The developed method has advantages over the best version of the method based on the period-time interval-code (PTC) conversion when working with the same initial value of the investigated frequency and when working with the same value of the averaging interval. Results. Analytical relationships were obtained for basic metrological characteristics. A comparative analysis was carried out for the metrological characteristics of the developed method and the method using period-time interval-code conversion. Acceptable metrological characteristics are inherent to the short-time frequency instability function (SFIF) measurement method based on the period-time interval-code technique. The difference of investigated and reference intervals form the measurement interval, which is filled with pulses of the investigated or reference frequencies. Conclusions. Stand-alone and virtual measurement devices were developed, and experimental studies of standard oscillators were carried out. The features of measurement devices were specified and the ways of their further improvement were described. Further development of the measurement device can involve an increase in the number of measured signal source with frequency output (SFO) parameters, in particular, changes in short-time frequency instability due to the action of destabilizing factors, and the characteristics and time of frequency setting. This calls for developing a controlled source of destabilizing factors and synchronizing its operation with the measurement device.