Instrument Function
R&S
®
SMB100A
200
Operating Manual 1407.0806.32 ─ 21
"External"
Uses an externally applied modulation signal.
The external signal is input via the MOD EXT connector.
" Extern"
Uses both, the internal and externally applied modulation signal, for
example to perform two-tone AM.
Note:
This setting applies to linear AM, see
ments with high frequency options)"
Remote command:
AM Type
Selects between linear or exponential (logarithmic) amplitude modulation, if you work
with an instrument that is equipped with a 12 GHz, or higher frequency option.
Remote command:
AM Depth
Sets the modulation depth in percent.
Note:
With two-tone modulation, observe that the set modulation depth applies to both
signals and the sum modulation depth is determined by doubling the set modulation
depth. This results in overmodulation if the maximal value for modulation depth is
exceeded (see data sheet).
For instruments with frequency option 12 GHz or higher, you can additionally select
. In this case, the generator sets modulation depth in dB (logarith-
mic).
Modulation is possible both, upwards and downwards. Accordingly, the dynamic range
extends for instruments without attenuator from minimum to maximum level. For instru-
ments with attenuator, the dynamic range corresponds to the
these are downwards about 20
dB, and upwards about 5
dB, that means in total about
25
dB around the set level.
Effects of positive/negative modulation depth:
●
–
positive depth -> downwards modulation
–
negative depth -> upwards modulation
●
–
positive depth and negative external voltage -> downwards modulation
–
positive depth and positive external voltage -> upwards modulation
–
negative depth and negative external voltage -> upwards modulation
–
negative depth and positive external voltage -> downwards modulation
Remote command:
[:SOURce<hw>]:AM:DEPTh:EXPonential
LF Gen Freq
Sets the frequency of the LF generator.
This setting affects all analog modulations which use the LF generator as the internal
modulation source.
Modulation
