Modulation - General R&S®SML / R&S®SMV03
1090.3123.12 E-6 4.10
Extrenal modulation sources for vector modulation
F
o
r external vector modulation, input connectors I and Q are available at the rear panel of the SMV03
(input impedances 50 ). To avoid the I/Q modulator being overdriven the input voltage should never
exceed I
2
+ Q
2
= 0.5 V.
Simultaneous Modulation
If vector modulation is deactivated then basically any combination of AM, FM/M/stereo and pulse
modulation is possible. There are restrictions only for FM,M. and stereo. The same is true for activated
vector modulation. Though, then there is an additional restriction for AM.
Two-tone AM and two-tone FM/M can be selected via menu (Modulation - AM (FM/M) - AM (FM/M)
Source - Two Tone).
Mutual Switch-Off of Modulation Types
As FM,M and stereo use the same modulator, they cannot be activated simultaneously. They
deactivate one another. In a similar way the same is true for AM and vector modulation. For AM the
level control has to be activated while vector modulation requires the level control being deactivated.
Note: IEC/IEEE-bus control according to SCPI does not allow the selection of the incompatible
modulation types FM,
M and stereo. With remote control, an error message is output
when an attempt is made to activate these types of modulation (see Chapter 9).
[MOD ON/OFF] Key
The various types of modulation can be switched on and off directly using the [MOD ON/OFF] key or via
the Modulation menu. If switch-on is made using the [MOD ON/OFF] key, the modulation sources which
are set in the modulation menus are used.
The [MOD ON/OFF] key can be effective either for all types of modulation or only for a selected
modulation. The selection of modulation types for which the [MOD ON/OFF] key is to be effective is
made in the Utilities – Mod Key menu.
If only one type of modulation is selected, it is switched on or off each time the [MOD ON/OFF] key is
pressed.
If all modulation types are selected, the [MOD ON/OFF] key has the following effect:
• If at least one modulation type is active:
Pressing the [MOD ON/OFF] key switches off all active modulation types. The modulation types
which were active are stored.
• If no modulation type is active:
Pressing the [MOD ON/OFF] key switches on the modulation types that were last switched off with
this key.
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