Fitting algorithm of sine wave with partial period waveforms and non-uniform sampling based on least-square method

A novel four-parameter sine wave curve-fitting method for partial period and non-uniform sampling is presented. Based on the three-parameter sine wave curve-fitting method, the principle of this method is to turn the optimization of four parameters (amplitude, frequency, phase and offset) into the optimization of only one parameter (frequency). Compared to other curve-fitting methods, the characteristics of this method is that it does not need initial parameter estimation, and can be used to fitting partial period sinusoid, even with only 1/5 signal periods or less. It is shown that this method has wide convergence interval and excellent robustness. The validity and feasibility of this method have been proved by both the simulations and experiment. The four-parameter sine wave curve-fitting method can be applied to the parameter estimation of sinusoidal wave with non-uniform sampling series of partial period, especially it is very useful in the control of ultra lower frequency sine wave parameters.