Noniterative method for frequency estimation based on interpolated DFT with low-order harmonics elimination

An Improvement of the Nonparametric Frequency Estimation Below Two Signal Periods Using Two Windows

“…8-curve d). The maximum errors are about ten times lower than with the classical two-point estimation (11) (Fig. 8-curve b).…”

“…The proposed interpolated DFT algorithm (21) [Fig. 4(a)] achieves maximum errors about ten times smaller than the classical two-point algorithm with the Hann window (11) [Fig. 4(b)].…”

“…The use of parametric methods requires a good signal model [8] and the uncertainty of the evaluation is typically reduced iteratively, which costs a lot of computing time. The nonparametric methods use the DFT to transform the sampled real signal into frequency space [9], [10], [11], [12], [13], where a basic image of the signal by components is obtained. The application of DFT involves two steps, namely, coarse search and fine search [14].…”

“…Traditional interpolated DFT focuses on estimating the parameters of a sine wave signal when the number of detected sine wave cycles is more than three. Advanced windowing functions and interpolation techniques [9], [10], [11] have been used to compensate for the leakage effects caused by incoherent sampling and finite frequency resolution. Since one of the research directions today focuses more on the speed of evaluation for faster responses of the measurement systems, a tradeoff between the accuracy of the measurement of the signal parameters and the length of the observation interval must be found for all nonparametric evaluation techniques.…”

“…where i(|G| max ) = 1 (the largest local amplitude DFT coefficient is at i = 1 and sign is s = 1 since the dc coefficient cannot be used in (11).…”