Setting Attenuation and/or Power Levels How to Use a Variable Optical Attenuator module
210 Agilent 8163A/B, 8164A/B & 8166A/B Mainframes, Sixth Edition
• To set the measurement Averaging Time used by the powermeter incorporated
in the Attenuator module, press [Menu] , select <Averaging Time>, press [OK],
select your preferred Averaging Time, press [OK], then press [Close].
As with any powermeter, a longer Averaging Time increases accuracy and
noise rejection, but increases response time.
Calibration Procedure
The power level measured by the integrated powermeter at the output of the
module is displayed as P
actual
. To calibrate your test setup, you apply a P
Offset
to
calibrate for the patchcord and connector losses that occur between the
Attenuator module output and the DUT input.
After calibration, you edit the Attenuator’s P
SET
parameter to control the absolute
power applied to the DUT.
1 Disconnect the DUT input in your test setup and connect it to your reference
powermeter.
•Set the λ parameter for the reference powermeter to the source wavelength
or, for a multi-wavelength DWDM signal, the effective wavelength
λ
effective
Refer to “Multi-wavelength DWDM signals” on page 207.
• Set an appropriate measurement <Averaging Time>.
2 Display the details screen for the Attenuator module.
•Make sure the λ parameter set for the Attenuator module matches the
source wavelength or, for a multi-wavelength DWDM signal,
λ
effective
.
• Make sure that the Averaging Time set for the integrated powermeter
matches that set for the reference powermeter.
3 If the reference powermeter is hosted by the same mainframe as the
Attenuator module:
• Select the P
Offset
field,
• Press the [PM-> Off ] softkey,
• Select the channel used to host your reference powermeter,
•Press [OK].
The difference between the power level measured by your reference
powermeter and the power value measured by your Attenuator P
actual
is stored
by the Attenuator module as P
Offset
, then applied to P
SET
and P
actual
.
4 If the reference powermeter is hosted by another mainframe:
• Manually enter the value of P
Off
•P
Off
= P
actual
- P
ref
•where P
ref
is the power level measured by your reference powermeter.
5 Disconnect the input to the reference powermeter, then connect it to the DUT
input.
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