taux de distorsion

CONT: [Dans le Teac AS M50] les taux de distorsion restent très faibles quelle que soit la puissance, et (...) la décroissance des amplitudes dans l'analyse du spectre de distorsion par harmoniques est régulière.

CONT: The [DFM] meter indicates the distortion factor, which is the ratio of the rms total distortion to the amplitude of the fundamental frequency, including harmonics.
OBS: A common measurement is total harmonic distortion (thd) where the fundamental of a very low distortion sine-wave test signal is removed by a steep notch filter. The summed harmonics that remain are then measured as a voltage of the fundamental at the required test power of the amplifier. (When measured in this manner the term thd is not really correct since the distortion also has the amplifier noise added to it within the test passband. The correct term is distortion factor). (GRAEL, 1977, p. 326).