Multi-Instrument Setups
R&S
®
SMBV100B
439
User Manual 1178.4460.02 ─ 03
In the R&S
SMBV100B, level values are represented as relative to a full scale (see
).
Where to find the necessary values?
●
Dialog "BB Input"
Chapter 8.6, "Digital Baseband Input Settings"
●
Dialog "Analog I/Q Out"
See
Chapter 8.7, "I/Q Analog Output Settings"
Why the instrument monitors the signal internally and how to avoid overflow
The R&S
SMBV100B constantly monitors the input and output digital signal and indi-
cates an overflow status.
●
Overflow of the
input signal
(Crest Factor and Peak Level) is indicated if the
entered "Peak Level" (in dB full scale) value does not correspond to the real value
Tip:
The overflow status is indicated as long as the signal level is not reduced and
the peak level value corrected. Trigger "Auto Level Set" to collect the required val-
ues and adjusts the settings automatically.
●
Overflow of the
output signal
is indicated if the digital signal is clipped, i.e. if the
level of the output signal, or the noise level (AWGN) are too high.
Specific Characteristics of the Digital I/Q Interface
What is a "digital channel" and how are the channels distributed to the base-
bands
The external digital signals supplied at the Dig I/Q interfaces of the instrument may
contain more than one, possibly even multiplexed, digital channels. The
R&S
SMBV100B processes each of these digital channels as a separate signal.
Fulfilling the prerequisites for a correct signal processing of the externally sup-
plied digital baseband signal
"Important Signal Parameters and Interface's Characteristics"
emphasis why and which signal parameters are important for the correct internal signal
processing of externally supplied signals in the R&S
SMBV100B. This section focuses
on the way these requirements are fulfilled and explains how the instrument deals with
signals deviating from the expected values:
●
Crest factor, peak level and RMS level
These values can be adjusted in one of the following ways:
–
Adjusted manually
If you have knowledge about these values, it is best to enter them directly
–
Estimated automatically by the internal measurement function
Use the function
to trigger the R&S
SMBV100B to measure the
input signal, estimate the peak level and RMS level and calculate the crest fac-
tor out of them.
Tip:
For a correct signal leveling:
Control and Operation of External Instruments
