VeEX FX150, Руководство пользователя

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OTDR Series e-Manual, RevE00 Page 99 of 128
The bottom of the screen displays:
•
Spl (km, meters, miles or feet) - distance of center marker
•
Loss of the event in dB based on the pre/post LSA sections and center marker
•
Reflectance in dB if event is reflective
8.2.6 Reflectance Measurement
Reflectance is measured in -dB (negative decibels). A smaller negative value (-65dB) indicates
a smaller reflection whereas a larger negative value (-45dB) indicates a larger reflection.
Larger reflectance will appear as a higher spike or peak on the trace and shorter EDZ
measurement.
To view the Reflectance:
1. Select trace for measurement (if multiple traces are displayed on screen). The trace to be
measured can be selected using the green arrow in the trace overview window.
2. Select
Reflectance (Refl)
from the drop-down list at the bottom of the screen.
3. Expand the trace horizontally and vertically (using Zoom Controls) to display the reflection
correctly. The entire reflection will be displayed including a small section of the trace
preceding and following the event.
4. Place the left marker on the base of the event’s rising edge. The right marker is placed on
the peak of the reflection or after the peak. The software will look for peak value.
The bottom of the screen displays:
• Distance of A cursor (reflection) from Start of test fiber
• Distance of B cursor (top of reflection) from Start of test fiber
•
Distance between markers A->B
•
Reflection for this even (-dB)