Anritsu 681XXC - Manual (Page 107)

q Select the input impedance (600
W or 50W) of
the input connector.
q Select the input connector (front panel or rear
panel
AM IN ) that is connected to the external
signal source.
Press On / Off to turn AM on and off. Both the AM
status display and AM modulation status area will
reflect your selection.
Press Log / Linear to select the AM operating mode.
The AM status display will reflect your selection as
XX dB/V (Log) or XX %/V (Linear).
Press Edit Sens to open the AM Sensitivity pa-
rameter, then edit the current value using the cur-
sor control key or rotary data knob or enter a new
value using the keypad and the appropriate termi-
nator key (
kHz/
m
s/STEPS for Linear; MHz/ms/dB for
Log). The AM Sensitivity range is 0 %/V to 100 %/V
in Linear and 0 dB/V to 25 dB/V in Log. To close the
open AM Sensitivity parameter, press
Edit Sens or
make another menu selection.
Press 600
W / 50W to select the input impedance of
the input connector. The AM status display will
reflect your selection.
Press Front / Rear to select the front panel or rear
panel AM IN connector. The AM status display will
reflect your selection.
Frequency
Modulation
Operating
Modes The signal generator has two FM operation modes
—Locked FM and Unlocked FM. In Locked FM
mode, frequency modulation of the output signal is
accomplished by summing the modulating signal
into the FM control path of the YIG phase-lock loop.
Maximum FM deviation is the lesser of
±10 MHz or
Fmod x 300 for 1 kHz to 500 kHz rates.
In Unlocked FM mode, the YIG phase-lock loop is
disabled to allow for peak FM deviations of up to
100 MHz. There are two Unlocked FM modes—Un-
locked Narrow and Unlocked Wide.
In Unlocked Narrow mode, frequency modulation is
obtained by applying the modulating signal to the
fine tuning coil of the YIG-tuned oscillator. Un-
locked Narrow FM mode allows maximum devia-
tions of
±10 MHz for DC to 500 kHz rates.
3-74 681XXC OM
LOCAL (FRONT SIGNAL
PANEL) OPERATION MODULATION
ERR
This error message is displayed
when the external AM modulating
signal exceeds the input voltage
range. The message “
Reduce AM
Input Level ” also appears at the bot-
tom of the AM status display. AM is
turned off until the modulating sig-
nal is within the input voltage
range.