SMIQ
Modulation - General
1125.5555.03
E-8
2.57
2.6.2 LF
Generator
The SMIQ is equipped with a LF-generator as internal modulation source as a standard. The generator
supplies sinusoidal signals in the frequency range from 0.1 Hz to kHz.
The frequency settings of the internal modulation signals can be made in one of the modulation menus
(AM, FM, PM) as well as in the LF-output menu. Figure 2-25 shows the setting parameters using the AM
menu as an example.
AM DEPTH
AM SOURCE INT
AM SOURCE EXT
AM EXT COUPLING
LFGEN FREQ
FREQ
250. 000 000 0
MHz
LEVE L
- 10.0
dBm
AM
15.5 %
OFF
INT
OFF
EXT1
AC
DC
1.000 0
kHz
FREQ UENCY
LEVE L
ANAL OG MOD
VECT OR MOD
DIGI TAL MO D
DIGI TAL ST D
LF OUTPUT
SWEE P
LIST
MEM SEQ
UTIL ITIES
AM
BB-A M
FM
PM
PULS E
Fig. 2-25
Example: Settings of the LF generator in the AM menu
2.6.3 Simultaneous
Modulation
Combination of AM and FM as well as AM and vector modulation is possible. Instead of FM, phase
modulation (PM) can be switched on as well.
Two-tone AM is possible by simultaneously switching on the external and internal source.
Two-tone FM or two-tone PM is possible by simultaneously switching on FM1 and FM2 or PM1 and
PM2. For FM1 and FM2 (PM1 and PM2) separate deviations can be set and separate sources switched
on.
Note:
With two-tone modulation please observe that the set deviation or modulation depth is valid for
one signal and the sum deviation or sum modulation depth is determined by adding both
signals. This results in overmodulation if the maximal value for deviation or modulation depth is
exceeded.