Instrument Function
R&S
®
SMJ100A
287
Operating Manual 1403.7458.32 ─ 14
5.6.2.4
Analog Wideband I/Q Input
In the bottom section of the menu the crest factor is input for the external signal and
the gain is selected for the internal and external signal ("Analog Wideband I/Q Input" or
"Internal Baseband").
Crest Factor - I/Q Mod
(Analog Wideband I/Q Input only)
Sets the crest factor of the external analog signal.
The crest factor gives the difference in level between the peak envelope power (PEP)
and average power value (RMS) in dB.
This value is necessary to allow the correct output power to be generated at the RF
output. When the set output power is generated, the R&S
SMJ uses this value to com-
pensate the average power which is lower compared to the peak power.
The maximum input voltage at the I/Q input is equated to the peak power and is used
as the "reference" for setting the level of the output signal. Since the signal does not
usually supply the peak power at a constant level and instead supplies a lower average
power, the crest factor specifies how many dB have to be added internally so that the
correct output power is achieved.
Remote command:
Baseband Gain-Gain - I/Q Mod
Optimizes the modulation of the I/Q modulator for any measurement requirement.
The modulation is determined by selecting the gain.
Note:
The remote-control commands to be used depend on the selected I/Q input signal
(
SOURce:IQ:SOURce ANALog | BASeband
).
●
For the Analog Wideband I/Q input signal, the commands of system
SOURce:IQ:GAIN
are valid.
●
For the internal or external Baseband I/Q input signal (
SOURce:IQ:SOURce
BASeband
), the commands of system
SOURce:BB:IQGain
are valid.
"Auto"
(digital baseband signal only)
With this setting, the modulation is automatically optimized for the
internally set baseband signal.
"- 3dB (Low
Distortion)"
Activates -3 dB gain. With this setting, signal distortions are mini-
mized.
"0 dB (Stan-
dard)"
Activates 0 dB gain
"3 dB (High
3GPP ACLR)"
Activates 3 dB gain. This setting is recommended for 3GPP signals
with very high adjacent channel power ratio (ACPR).
"6dB (Low
Noise)"
Activates 6 dB gain. With this setting, signal noise is minimized.
I/Q Modulation - I/Q Mod Block
Summary of Contents for SMJ100A
Page 34: ...Preface R S SMJ100A 18 Operating Manual 1403 7458 32 14 Notes on Screenshots...
Page 86: ...Preparing for Use R S SMJ100A 70 Operating Manual 1403 7458 32 14 LXI Configuration...
Page 826: ...Remote Control Commands R S SMJ100A 810 Operating Manual 1403 7458 32 14 UNIT Subsystem...
Page 828: ...Maintenance R S SMJ100A 812 Operating Manual 1403 7458 32 14 Storing and Packing...
Page 844: ...Hardware Interfaces R S SMJ100A 828 Operating Manual 1403 7458 32 14 BERT Connector...
