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Selected Line
The WDM channel analyzer displays separation on this
spectrum as shown in the following figure. Notice that
the 1541.747 nm laser line is selected as the reference.
It is shown in absolute units. The wavelengths and pow-
ers of the remaining responses are shown relative to
this reference. For example, the first response is
2.596 nm below the reference.
To determine channel spacing, simply read the relative
wavelength measurement of the laser lines immediately
preceding and following the reference. Use the
and SELECT softkeys to change the reference laser line
and read the channel spacing between each channel.
To measure channel separation
1 Press the front-panel Delta key.
2 Select the type of separation to observe:
• ∆ WL displays channel separation.
• ∆ PWR displays differences in power.
• ∆ WL / ∆ PWR displays both channel separation and
differences in power.
3 Use the
and
line.
4 Press SELECT.
Press SELECT at any time to select a new reference.
Press RESET at any time to turn off the delta calculation.
You can use relative power measurements to measure
flatness (pre-emphasis) in a WDM system. Simply
select one carrier as the reference and measure the
remaining carriers relative to the reference level. The
power differences represent the system flatness.
Measuring Laser Separation 3-13
softkeys to select the reference laser
Delta Annotation
,
,
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