Rohde & Schwarz R&S UPP, User Manual

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Instrument Functions
R&S
®
UPP
384 User Manual 1411.1055.32 ─ 10
"activated" Bargraph computation (and update) enabled. The remaining settings
dynamically define the associated measurement function.
Remote command:
SENSe[1]:FUNCtion:BARGraph
on page 758
Post FFT
Activation of the Post FFT; furthermore, the graphics window "FFT Graph1" can be
opened from here.
For details, see Chapter 5.26.3, "Post FFT" , on page 411.
5.23.2 THD
THD (total harmonic distortion) is a measurement of distortion over the first 8 harmon-
ics or over any combination of the first 8 harmonics (d2 to d9), wherein the amplitudes
of the individual harmonics amplitudes are measured selectively. The root from the
square sum of the harmonics can be displayed either as an RMS or as a ratio to the
total RMS. Unlike with THD+N & SINAD measurement, the noise between the harmon-
ics is
not measured.
An ultra-pure sine-wave signal is required as the measurement signal. The selected
frequency of this sine-wave signal should be such that the significant components of
the distortion spectrum are still below the upper measurement limit.
If the first harmonic lies above the set IF bandwidth, an error message appears in the
user info line and the measured value is identified as invalid (---).
The "sine" signal function of the internal generator is recommended as the signal
source . The sine-wave level and frequency can be varied or swept.
For alternative distortion measurement, see Chapter 5.23.3, "THD+N & SINAD" ,
on page 389.
For more distortion measurements, see Chapter 5.23, "Distortion Measurements" ,
on page 381.
Distortion Measurements