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Modulation Keys
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Pressing the (FM MODE St) key displays the current FM mode and allows it to
be changed if desired.
When this key is pressed the current FM mode is displayed in the
MARKER/SWEEP/STATUS area. The mode can be changed to the next choice
by pressing the
(FMj’D
key again, or by pressing the
0J
(JJJ
keys. The
FM mode choices are:
FM Off
In this mode, external FM modulation is disabled. The
displayed message is
FM=Of
f
.
AC/Locked FM
In this mode, the RF output signal is synthesized, and
external FM modulation is enabled. The bandwidth is
restricted to above approximately 50
kHz.
The user is
cautioned that the low-frequency deviation is limited in
this mode to approximately 25 times the rate of the signal.
The front-panel EXT MOD annunciator is turned on. The
displayed message is
FM=HC:.~‘Lcd
4.
DC/Unlocked
In this mode, the RF output signal is not
s~thesized,
and
FM
external FM modulation is enabled, with a bandwidth that is
dc-coupled. In this mode, the RF frequency accuracy and
residual FM are severe& degraded, and may be out of spec.
The front-panel UNLOCKED FM LED annunciator is turned
on, The EXT MOD annunciator is turned on. The displayed
message is
FM=[)i::..~‘l~r~lc~~~ked.
Associated SCPI Commands
FM:COUPling AC
Sets the FM mode to AC/locked
FM
FM:COUPling DC
Sets the FM mode to DC/Unlocked
FM.
FM:STATe ON
iirns
on the selected FM mode,
FM:STATe OFF
Turns
FM mode ofi
10-7
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General