Rohde & Schwarz R&S UPP, User Manual

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Instrument Functions
R&S
®
UPP
389 User Manual 1411.1055.32 ─ 10
5.23.3 THD+N & SINAD
THD+N & SINAD (total harmonic dist noise) is a distortion measurement that
measures and displays the energy of the broadband noise
without the fundamental
(residual signal) within a selectable frequency band (optionally, the energy can also be
displayed relative to the total energy). This measurement function allows different mea-
surement modes; it is also possible to eliminate the harmonics, except for the funda-
mental, so that the measured value only contains non-harmonic components and
noise.
An FFT is used to record the spectrum, filter out the fundamental and calculate the
total remaining energy (residual spectrum) – comprising of harmonics and broadband
noise – within the band limits specified with "Frq Lim Low" and "Frq Lim Upp". The FFT
value is automatically adapted to the measured fundamental frequency; the lower the
frequency is, the longer the required FFT and, therefore, the integration time will be.
The user can select the minimum FFT value :
●
implicitly by selecting the rejection bandwidth (with deactivated Post FFT)
●
explicitly by selecting the minimum FFT length "Min FFT Size " with activated "Post
FFT ".
Distortion Measurements