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FTTx-PON network optical fiber spans are different from normal optical fiber spans. There is a branching
aspect to the span. The user needs to be aware of the following, when testing FTTx-PON:
10.1 Using the PON-Optimized OTDR Module
Some models are optimized specifically for testing FTTx-PON network optical fiber spans, and can
achieve highly accurate trace results.
Due to the higher sensitivity, it is important to correctly set the distance range, end threshold (optical
fiber end detecting threshold) and reflection threshold ( reflection detecting threshold).
10.2 Selecting the Proper Distance Range
Because there is branching in FTTx-PON network optical fiber spans, there will be significant attenuation,
resulting in innacurate automatic calculation of the span’s length. We therefore highly recommend
manually selecting the parameters, such as the distance range, pulse width and other thresholds.
10.3 End Threshold (Optical Fiber end Detection Threshold)
For normal optical fiber spans, the end threshold configuration can remain set at 3.0dB. For PON
network testing, however, the user will need to set the end threshold to a proper value, then the PRO TP-
P6 can locate the end accurately. Please refer to Table 10.1 (shown below) as a reference.
10.4 Test Parameter - Recommended Values
Splitter Type Loss Reference Value
End Threshold Configuration
Reference Value
Recommended Test
Pulse Width
1:8 ≥ 9dB 12dB 100ns, 300ns
1:16 ≥ 12dB 15dB 100ns, 300ns
1:32 ≥ 15dB 18dB 300ns, 1us
1:64 ≥ 18dB 21dB 300ns, 1us
Table 10.1 Recommended parameter values for PON network optical fiber spans
10 Using the OTDR to Test FTTx-PON Network
Optical Fiber Spans