Summary
It follows from the theoretical and experimental investigations that the error of measurement by the above method for a zero intermediate frequency and a sinusoidal modulation is equal to\(\frac{\pi }{{2(\Delta f/F)}}.\) 100%, i.e., it drops with a rising modulation index. The deviation of the intermediate frequency from zero has a small effect on the measurement results [the additional error due to this factor is of the order of (f if/Δf)2]. Since the error of the frequency counter can normally be neglected, the only source of error for a large modulation index, in fact, consists of the modulating function deviation from a sinusodial shape. For a small nonlinear distortion coefficient this error is of the same order as the coefficient.
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Literature cited
G. V. Dlugach and I. M. Sorkin, Radiotekhnika No. 7 (1947).
I. S. Gonorovskii, Foundations of Radiotechnology [in Russian] (Svyaz'izdat, Moscow, 1957).
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Shpan'on, P.A. Measurement of frequency deviations in FM oscillations by means of a frequency meter. Meas Tech 4, 650–654 (1961). https://doi.org/10.1007/BF00978141
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DOI: https://doi.org/10.1007/BF00978141