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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).
The LSA (Least-Squares Approximation) method uses 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.
The LSA method only measures the amplitude (decibel) change between the crossing points of the trace
based on Marker A and B.
Compared to the 2-Point method, the LSA method is more accurate because it is less sensitive to trace
noise and more suitable for measuring splice attenuation. However, the LSA method should not be
applied to measuring attenuation when there are reflection events between Markers A and B.
Measuring attenuation:
1. Click {Markers} tab in OTDR main interface to show Marker A and B.
2. Place Markers A and B at different points on the trace.
3. Zoom-in on the trace to adjust the Marker position when necessary.
4. Check 2Pt. Atten. (2-Point Attenuation) and LSA Atten. (LSA Attenuation) values, as shown in Fig. 12.5.
Note:
There should not be any event between Marker A and B when measuring attenuation
with the 2-Point method.
Fig. 12.5 Viewing Attenuation
12 Manual Trace Analysis
Содержание TP-P6
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