Determn. of harmonics of fundamental oscillation of electrical signal

摘要

The signal (U) is sampled (1) at a selected frequency and digitised (2). The digital values are subjected to a discrete Fourier transform (3) and the spectral lines at the fundamental frequency and eight harmonics are displayed on a monitor (4). The digitised signal is also input to a frequency meter (7) associated with a clock signal source (6). The measured frequency is multiplied (9) by the ratio (n) of the sampling frequency (fA) to the nominal fundamental frequency of the analogue signal. The prod. passes to a divider (10) clocked at the same rate (fQ). Another divider (11) produces the frequency for sampling and digitisation.