Rohde & Schwarz SMIQ02B - Fig. 2-24 Example: Status Message EXT1-LOW in Case of Voltage at EXT1 too Low; Table 2-2 Status Messages in the Case of a Deviation from the Rated Value at the External Modulation Inputs EXT1 and EXT2

Modulation - General SMIQ
1125.5555.03 E-82.56
EXT1/EXT2-Inputs
The external modulation signal for AM, FM and PM at inputs EXT1 and EXT2 must show a voltage of
V
s
= 1 V (V
eff
= 0.707 V) in order to maintain the modulation depth or deviation indicated. A monitoring
circuit checks the input voltage in the frequency range 10 Hz to 100 kHz. Deviations of more than ±3 %
are signaled in the status line by means of the following messages (cf. Table 2-2). The inputs EXT1 and
EXT2 can be AC- or DC-coupled. Monitoring is only active if the inputs are AC-coupled.
Table 2-2 Status messages in the case of a deviation from the rated value at the external modulation
inputs EXT1 and EXT2
Message Deviation
EXT1-HIGH Voltage at EXT1 too high
EXT1-LOW Voltage at EXT1 too low
EXT2-HIGH Voltage at EXT2 too high
EXT2-LOW Voltage at EXT2 too low
EXT-HI/HI Voltage at EXT1 and EXT2 too high
EXT-LO/LO Voltage at EXT1 and EXT2 too low
EXT-HI/LO Voltage at EXT1 too high and EXT2 too low
EXT-LO/HI Voltage at EXT1 too low and EXT2 too high
FREQ
250. 000 000 0
MHz
LEVEL
- 10.0
dBm
AM
30.0 %
OFF INT
OFF EXT1
AC DC
1.000 0 kHz
FREQUENCY
LEVEL
ANALOG MOD
VECTOR MOD
DIGITAL MOD
DIGITAL STD
LF OUTPUT
SWEEP
LIST
MEM SEQ
UTILITIES
AM
BB-AM
FM
PM
PULSE
EXT1-LOW
AM DEPTH
AM SOURCE INT
AM SOURCE EXT
AM EXT COUPLING
LFGEN FREQ
Fig. 2-24 Example: Status message "EXT1-LOW" in case of voltage at EXT1 too low
I/Q Inputs
The nominal voltage at the I/Q-inputs for external vector modulation is U
s
= 0.5 V. Input resistance is
50 Ω. For a more detailed description, cf. Section "Vector Modulation".
For external broadband AM the I-input is used. Input sensitivity is 0,25 V for 100% AM.