AD1000 User’s Manual
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12.4 Measure Attenuation (2-point and LSA
method)
2-point method measures the attenuation between Marker A and B calculated by all
the loss over the distance between Marker A and B (Unit: dB/Km).
LSA (least-squares approximation) method use linear regressions that is applied to
the backscatter before and after an event (Between Marker A and B) to estimate the
attenuation in the backscatter resulting from the event’s loss. LSA method only
measures the amplitude (decibel) change between the crossing points of the trace
with Marker A and B.
Compared to 2-point method, LSA method is more accurate because it is less
sensitive to trace noise and suitable for measuring splice attenuation. However, LSA
method should not be applied to measure attenuation when there are reflection
events between Marker A and B.
Measure attenuation:
1.
Click {Markers} label in OTDR main interface to show Marker A and B.
2.
Place Marker A and B at different points on trace.
3.
Zoom in the trace to adjust marker position when necessary.
4.
Check 2Pt. Atten. (2-point attenuation) and LSA Atten. (LSA attenuation)
values, as shown in Fig. 12.5.
Fig. 12.5 View attenuation
There should not be any event between Marker A and B when
measuring attenuation with 2-point method.
