EXFO IQS-3150 Variable Attenuator for IQS-500/600 - Manual (Page 33)

Setting Up Your Variable Attenuator
Variable Attenuator 27
Basic Settings
Setting the Drift Tolerance
The drift tolerance setting is only available for the self-adjusting modules
and is only applicable for the Power Tracking function (see Using the
Power Tracking Function (Self-Adjusting Modules) on page 52).
When you use the power tracking function, the internal power meter
monitors the output power level and constantly adjust the attenuation to
ensure that the output power does not exceed the limits set by the user
(drift tolerance). For example, if the power of the source used for the test
drifts over time, the attenuation is adjusted so that the output power
remains within the preset limits.
Requested
power
Source power
fluctuation
Power adjusted
by the attenuator
Drift
tolerance
Time (minutes)
Ou
tp
ut p
ower
(dBm)