A METHOD TO OBTAIN EXACT FREQUENCY CHARACTERISTICS OF HARMONIC SIGNALS

Accurate frequency characteristics are critical in some dynamics measurement. Power leakage in FFT can result in considerable error in the calculation of the frequency characteristics. In this paper, an optimising approach is developed to determine the exact frequencies of experimental harmonic signals. The experimental signal is resampled in a sample duration of an integral number of the signalʹs period. The resampling duration is computed via an optimisation algorithm. The leakage error in FFT is avoided and the accuracy in the calculation of the frequency characteristics is greatly increased. Detailed procedures and experimental examples are presented.