Configuring the Internal Baseband Source
R&S
®
SMBV100B
230
User Manual 1178.4460.02 ─ 03
Note:
Wrap-around and timing problems can occur when I/Q signals of different length
are used. Thus, demodulation of a carrier can be difficult or even impossible.
We recommend that you proceed as follows:
●
Consider the timing when creating the input I/Q files.
●
Adjust the signal duration to the carrier which is then demodulated.
(In this case, the other carriers are for interfering the signal only.)
These problems do not arise with signals of the same standard (e.g. 3GPP).
The following modes are available:
"Longest File Wins"
The longest I/Q file in the carrier table defines the resulting signal
period. Shorter I/Q files are periodically repeated.
"Shortest File Wins"
The shortest I/Q file in the carrier table defines the resulting signal
period. Only the first part of longer I/Q files is used.
"User"
The signal period is set manually (
repeated periodically, and only the first part of longer I/Q files is used.
"Least Common Multiple"
The output file duration is the least common multiple of all input file
durations.
Remote command:
[:SOURce<hw>]:BB:ARBitrary:MCARrier:TIME:MODE
Signal Period
Sets the signal period in Signal Duration Mode "User". Shorter I/Q files are repeated
periodically, and only the first part of longer I/Q files is used.
Remote command:
[:SOURce<hw>]:BB:ARBitrary:MCARrier:TIME
Power Reference
Defines the way the individual carriers in a composed multi carrier signal are leveled.
The difference between the provided modes is especially important if signals with dif-
ferent crest factors are composed together into a multi carrier signal.
"RMS"
The individual carriers are leveled based on their RMS power and the
configured "Carrier Gain".
Example:
A multi carrier signal is composed from two waveform files.
First carrier "Gain" = 0 dB
Second carrier "Gain" = -3 dB
In the resulting multi carrier signal, the
RMS power
of the second car-
rier signal will be 3 dB lower than the RMS power of the first carrier
signal.
Generating Multi-Carrier Signals
