Phase sensitive frequency estimation algorithm for asynchronously sampled harmonically distorted signals

An algorithm for the estimation of the frequency from asynchronously sampled harmonically distorted signals is described. Phase difference calculation in the time domain using a three-parameter sine fit algorithm is proposed as a basis for estimating the sampled signal frequency. Comparison with standard four parameter sine fit algorithm (4PSF) and three-point interpolated DFT algorithm (I3DFT) demonstrates improved frequency estimation for harmonically distorted signals when at least 2 signal cycles are sampled.