Marconi Instruments 2040 - RF Level; Utility

RF level utility
Selecting
[RF Level Utility] from the Utilities Selection Menu 2 displays the RF Level
Utility Menu shown in Fig.
3-1-33.
LOCAL
Extended
Over-
range
RF Level
Utility Menu
Extended Hysteresis
:
ENABLED
Overrange Control : ENABLED
Offsets
C0938
Fig.
3-1-33
RF
level utility menu
Extended hysteresis
Pressing the [Extended] soft key toggles
the status
(Enable/Disable)
of extended
hysteresis. When enabled, this provides an electronic level
function
which
uses the internal D/A
converter,
rather than the attenuators, to provide
an
uninterrupted
(glitch-free)
level
control.
This increases the electronic level control
from ±7 dB to
+12
to
-18
dB. A +HYST or -HYST
message
is displayed on the Sig Gen menu to indicate
when
in hysteris and
in
which
direction.
During normal operation the RF output is controlled
as
shown
in Fig.
3-1-34
by
electronically controlling the output level over
a limited range (normally approximately 0 to +6
dBm) and switching
in 6 dB attenuator pads to provide lower RF levels.
When
the hysteresis function is enabled and
a
keyboard
entry of
the RF level
is made, the
signal generator sets the
level
in the normal way.
However, when the rotary control is enabled
and used to adjust the
RF level,
the normal attenuator changes are suppressed. When
the
level
is
increased, the attenuator change is suppressed
for 6 dB above the normal range and +HYST
is
displayed. Similarly, when
the level is reduced attenuator changes
are suppressed for 12 dB
below the normal range and -HYST is displayed.
When the extended hysteresis range is
exceeded
the attenuator and the electronic control are reset to values corresponding
to the normal
operation of the generator. An example of extended
hysteresis operation is shown in Fig.
3-1-35.
With the rotary control in use in the hysteresis
range of operation, the generator can be
instructed
to set the RF
level
to the same
value,
but set using the [V], [mV],
[pV] or [dB] keys.
This is a useful facility if the user is investigating squelch
systems and wants to ensure that
varying the level around
the current value will not result in an attenuator change.
3-1-42
46882-074C