Recovery of harmonic signal from discrete samples

The change–over from direct analog methods of measuring signal parameters to digital methods based on the use of analog–to–digital conversion (ADC) and microprocessor devices can be promising in the construction of various sensors. In this case, the estimation of the signal parameters is obtained not from the analysis of the likelihood function, but by solving the corresponding equations whose roots are unknown parameters: frequency, phase and amplitude of the signal. The necessary formulas are given for calculating the unknown parameters of the harmonic signal by the described method and for evaluating the accuracy of the calculations. The influence of the ratio of the sampling interval and the signal period on the calculation errors was analyzed. Thus, the problem was solved: using digital samples of a harmonic signal with slowly changing amplitude, determine the most reliable characteristics of the original analog signal. Ref. 9, pic. 4, tabl. 2