Rohde & Schwarz R&S UPP, User Manual

Page: 409 / 938

Instrument Functions
R&S
®
UPP
393 User Manual 1411.1055.32 ─ 10
Remote command:
SENSe[1]:THDN:REJection
on page 760
Reject Bandw
Used to select the suppression bandwidth ("Rejection Bandwidth") by implicitly enter-
ing the initial FFT value.
Only functions with deactivated Post FFT; with activated Post FFT, the initial FFT value
must be specified explicitly by the user.
The larger the bandwidth is (absolute frequency band around the fundamental), the
smaller the initial FFT and the higher the measurement speed will be.
The actual initial value of the FFT is determined automatically taking the sampling rate,
the analog bandwidth and the dynamic range of the used analyzer into consideration.
The final value of the FFT is determined by the frequency of the measurement signal;
it is increased automatically with low frequencies.
Apart from the measurement frequency, the actual measurement time also depends on
the analog bandwidth and sampling frequency.
Note: When the Post FFT is activated, the internally calculated initial FFT value is
entered in the "Min FFT Size" parameter field. It can then be freely changed by the
user.
"1 kHz max" The suppression bandwidth is a maximum of 1 kHz, i.e. 500 Hz both
below and above the fundamental.
The initial FFT value is very small (e.g. 1
k at an analog bandwidth of
22 kHz and a sampling rate of 48 kHz), and the measurement time is
very short – especially at higher frequencies.
Non-harmonic signal components close to the fundamental are not
measured.
Recommended for fast measurement of the harmonics.
"240 Hz max" The suppression bandwidth is a maximum of 240 Hz, i.e. 120 Hz both
below and above the fundamental.
The initial FFT value is at least 4
k.
Compromise between measurement time and loss of sideband
energy
"60 Hz max" The suppression bandwidth is a maximum of 60 Hz, i.e. only 30 Hz
both below and above the fundamental.
The initial FFT value is not below 16
k.
Recommended for measuring signal components close to the funda-
mental and especially for noise measurements as this bandwidth
ensures that the fundamentals and harmonics are suppressed as nar-
rowly as possible.
Remote command:
SENSe[1]:FUNCtion:APERture:MODE
on page 753
Distortion Measurements