EXFO FTB-7000 OTDR for FTB-200 v2 - Manual (Page 184)

Analyzing the Results Manually
170 FTB-7000 Series
Getting Event Loss (Four-Point and Least-Square Approximation)
To get event loss:
1. From the main window, select the Measure tab.
2. In the Results section, press Loss. Markers a, A, B and b appear on the
graph.
3. Zoom in and position marker A at the end of the linear area preceding
the event to be measured. For more information, see Using Zoom
Controls on page 123 and Using Markers on page 165.
4. Position submarker a at the beginning of the linear area preceding the
event to be measured (must not include any significant events).