High accuracy DFT-based frequency estimator for sine-wave in short records

The accurate frequency estimation of a noise-contaminated sine-wave is crucial in most fields of technology. Wherein the DFT-based methods are widely used for efficiency and considerable accuracy. However, under asynchronous sampling, the DFT suffers from the leakage from the negative frequency component which cannot be ignored, especially within a short sampling period. To estimate the sine wave unbiasedly in short records, a two-point DFT-based frequency estimator using the rotational technique is proposed in this paper. The proposed method first calculates the ratio of two selected rotational spectral lines adjacent to the peak, considering both positive and negative frequency parts. Then an analytical solution of the frequency is achieved using the ratio. In particular, the frequency measurement cases with short records are thoroughly examined and optimized. Simulations and practical tests validate that, the proposed method outperforms the state-of-art competitors even when the cycles in records are smaller than 1.