Fm Mode - HP 83751A User Manual

Pressing the ( St) key displays the current FM mode and allows it to

FM MODE

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
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
DC/Unlocked In this mode, the RF output signal is
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
FM:COUPling AC
FM:COUPling DC
FM:STATe ON
FM:STATe OFF
is FM=[)i::..~'l~r~lc~~~ked.
Associated SCPI Commands
Sets the FM mode to AC/locked FM
Sets the FM mode to DC/Unlocked
FM.
Modulation Keys
not s~thesized,
and
10-7