EXFO IQS-3150 Variable Attenuator for IQS-500/600 - Manual (Page 12)

Introducing the IQS-3150 Variable Attenuator
6 IQS-3150
Main Software Features
Display Modes
Both standard and self-adjusting modules give you a choice of three
display modes: Absolute, Reference, and X+B.
Attenuation
Display Mode Description
Absolute
(default mode)
The displayed attenuation takes into account both the absolute value
and the offset value.
Displayed att. = absolute att. + offset value
Reference The displayed attenuation value is relative to a defined reference value
(see Selecting a Display Mode on page 30).
Displayed att. = absolute att. – reference value + offset value
X+B The displayed attenuation is the sum of two elements:
³
X = physical attenuation introduced by the unit.
³
B = correction factor (dB). You must define the correction factor
for the test wavelength before enabling the X+B mode (refer to
Setting the B Value on page 23).
Displayed att. = absolute att. + correction factor
a
+ offset value
³
B = input power value (dBm)
Displayed att. = (absolute att. × –1) + input power
a
+ offset value
a. The correction factor and the input power value are specific to the wavelength.