Abstract
The calculation formula for zooming FFT, by which zoom FFT analysis can be carried out on a personal computer without any special FFT instruments, was derived by applying the same procedure that the Fast Fourier Transform was derived from discrete Fourier transform. According to the derived formula, a BASIC program of zoom FFT was coded, and was applied for analyzing the gear transmission errors measured on two tested gear pairs. By selecting a zoom ratio equal to the lowest common multiple of their gear- and pinion-tooth number devided by the gear tooth number, their gear- and pinion-low harmonics were distinctly separated and extracted without piket fence effect. And the amplitudes of the pinion low harmonics corresponded well with the hearing noise levels of the tested gear pairs.
