Amplitude Modulation - AM R&S SMB
1407.0806.32 4.62 E-2
External Modulation Sources
The modulation inputs MOD EXT and PULSE EXT at the rear of the instrument are provided as the
external modulation source for amplitude, pulse, frequency and phase modulation.
The external modulation signal at the inputs must have a voltage of V
s
= 1 V (V
eff
= 0.707 V) in order to
achieve the displayed modulation depth and range. The input voltage should not exceed 1.1 V
s
,
otherwise modulation distortions might occur. With external pulse modulation, the switching point is
max. 2.4 V and the voltage at the input should not exceed 5 V. The maximum modulation frequency is
10 MHz for frequency and phase modulation.
Simultaneous Operation of Several Modulations or Other Operating
Modes
The table shows the modulations and operating modes which can be activated simultaneously (+) or
which deactivate each other (-).
AM FM PhiM Pulse
Amplitude modulation (AM)
/ + + -
Frequency modulation (FM)
+ / - +
Phase modulation (PhiM)
+ - / +
Pulse modulation (R&S SMB-K22)
- + + /
Amplitude Modulation - AM
An internal and/or external source can be selected for amplitude modulation. A LF modulation generator
isavailable as the internal source. Two-tone AM is possible by simultaneously switching on the external
and internal source.
The MOD EXT input connector for external feed of analog modulation signals is at the front of the
instrument. The coupling mode of the input (AC or DC) can be selected.
Amplitude Modulation Menu
The Amplitude Modulation menu is opened in the Mod function block or using the MENU key under
Mod.
In the upper section of the menu, the modulation source is selected and the modulation switched on.
The modulation source can be selected independently for the different modulation types and the LF
output. The configuration of the selected external and/or internal modulation source is performed in the
lower section of the menu or in the Mod Gen block (internal source only). These settings affect all
modulations which use the same modulation source.
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FAX 781.665.0780 - TestEquipmentDepot.com
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