(POWER LEVEL), the ALC level and attenuator are set automatically to
provide the most accuracy for the power requested.
Uncoupled Operation.
In some applications it is advantageous to
control the ALC level and attenuator separately, using combinations
of settings that are not available in coupled operation. In uncoupled
mode
(Uncoupl
Atten
), when the desired power output is set via
POWER LEVEL), only the ALC level is changed. The attenuator setting
is changed via Set
Atten.
One use of uncoupled operation is power sweep, where the
output power linearly tracks the sweep voltage ramp. The
swept CW generator can generate power sweeps of up to 40 dB,
depending on frequency. The power at the start of the sweep is
set via POWER LEVEL (coupled operation) or by a combination of
[POWER LEVEL) and Set
Atten
(uncoupled operation). The sweep
range is entered by selecting Power Sweep. If the sweep range
entered exceeds the ALC range (stop power greater than maximum
available power), the UNLVLED warning message appears at the end of
sweep. No warning is given at the time of entry. If the start power is
entered when the swept CW generator is in coupled operation, the
ALC level is set no lower than -10
dBm,
limiting the available power
sweep range. Using uncoupled operation and setting the ALC level to
-20
dBm
gives an additional 10 dB of sweep range.
External Leveling
-
Leveling Mode Normal.,
Leveling Point
ExtDet
or
PwrMtr
or Module
In externally leveled operations, the output power from the swept
CW generator is detected by an external sensor. The output of this
detector is returned to the leveling circuits, and the output power is
automatically adjusted to keep the power constant at the point of
detection. Figure A-2 shows a basic external leveling arrangement.
The output of the detected arm of the splitter or coupler is held
constant. If the splitter response is flat, the output of the other
arm is also constant. This arrangement offers superior flatness over
internal leveling, especially if long cables are involved. Flatness
may be improved with user flatness correction ( FLTNESS ON/OFF ,
Fltness Menu
)
applied at the external leveling point.
Operating and Programming Reference A-7
To Next Page
Loading...
Need help?
General
