Localization of spectral peaks by method of parametric discrete Fourier transform

Abstract

In practice, the frequency of the investigated harmonic signal is usually located between the center frequencies of FFT bins. As a result, due to leakage effect, the frequency of the sinusoidal signal is measured with an error equal to half of frequency interval between the DFT bins. It is shown that if the frequency of a harmonic component is the same as the center frequency of one of the bins of the DFT, there are no problems associated with manifestation of the leakage effect, and frequency of a sinusoidal signal is measured with an error tending to zero. The known method of frequency signal measuring based on supplementing original signal with zeros in the time domain allows reducing the error of measuring frequency of the original signal due to reducing the frequency interval between the bins of the DFT. The disadvantages of this method are: the need for a substantial expansion of RAM for storing zero signal values; performing unproductive operations with zero signal values; frequency discretization step fixity in the measurement of frequency spectra; a significant increase of frequency measurement time. An efficient method of signal frequency measurement based on the parametric discrete transformation is proposed and its application areas are shortly described.