EXFO FTB -5240S/5240BP Optical Spectrum Analyzer for FTB 500 (NS-1434) - Manual (Page 352)

Managing Results
344 FTB-5240S/5240BP
Managing DFB Test Results
Markers Tab
You can use markers to perform manual measurements and verification
directly on the trace. There are two vertical markers indicating the
wavelength positions, which you can also move directly on the trace using
the zoom select option. You can measure actual power and wavelength
values of any point on the trace.
Note: These markers are visible in the DFB Graph tab only when the markers tab
is selected in the main window.
When the markers are set, you will find two markers identified by the
letters A and B in the DFB Graph tab. These markers are represented both
in the graph and the markers tab to customize your markers.
The application allows you to fix the distance between the vertical
markers. When this feature is activated, while moving any one marker,
both markers shall move at the same rate and distance.
The markers A and B in the Markers tab act as toggle buttons to enable
selection. When a marker is activated, the colour of the button changes to
orange and the selected marker displays a double arrow at the base of the
marker in the DFB Graph tab, which means that the marker can be
moved.
At this point, if you press the other vertical marker in the DFB Graph tab,
the selection of the toggle switches to this marker. However, if you select
the other marker button from the Markers tab, both the markers will be
selected and the distance between both will be locked.