Digital Measurement of Frequency with Linear Interpolation in Dynamic States

Abstract

Digital frequency measurements of small values of frequency are based on the measurement of the period of investigated signal. The result of measurement corresponds to the mean value of frequency in the defined time window. The instants which start the measurement depend on the position of the slope of the measured signal. For this reason it is impossible to compare the results of measurements in different measuring channels or to compare the results from frequency channels and voltage channels. The results are delivered in different intervals and therefore it is impossible to calculate Fourier transform. Good results can assure the linear interpolation. In the paper two methods (on-line and off-line mode) realized with buffered counters are presented. The simulation proves that good results of measurements can be obtained in case of a little amount of noises in the measured signal. Ill. 7, bibl. 5 (in English; summaries in English, Russian and Lithuanian).