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FAQs
END1) the user must change the “OTDR Located At” in the Job Settings screen to the other end
(END2 in this case) when running the test in the other direction. Bi-directional Analysis must be set
to “ON” in the Events Setting Screen.
Q:
Must the same OTDR settings be used from each end to perform bi-directional averaging?
A: Yes. The OTDR must be set to the same range and pulse width settings for both traces in order
to average the results. Otherwise the result will not be calculated by the OTDR.
Q:
If I use a launch ber when testing from one end, must I also use a launch ber of the same
length when testing from the other end?
A: It is recommended that the same launch cable be used in both directions to ensure the greatest
accuracy in the average Link Loss calculation. While in theory different launch cables (either of the
same or different length) could be used in each direction the bi-directional averaging of Link Loss
may be skewed by differences in connector losses between cables.
Q:
If I use a receive ber when testing from A -> B, must I also use a receive ber of the same
length when testing B -> A?
A: It is recommended that the same receive cable be used in both directions to ensure the greatest
accuracy in the average Link Loss calculation. While in theory different receive cables (either of the
same or different length) could be used in each direction the bi-directional averaging of Link Loss
may be skewed by differences in connector losses between cables.
Q:
If an event is detected in A -> B direction, but not in the B ->A direction, can results still be
averaged? If so, how is the average loss computed for the event detected in one direction but
missed in the other direction?
A: The “missing event” is added as a 0 dB loss event. The average loss is ½ the measured loss of
the automatically detected event (Avg = (measured + added 0 dB) / 2)
Q:
If the ber in A -> B direction was measured at a signicantly different length than in the B ->
A direction, can the traces be averaged?
A: No. If length in the second test direction is signicantly different than the length measured
in the rst test direction then a screen will pop up indicating that the unit is unable to perform
bi-directional analysis due the mismatch in link lengths.
Micro/Macrobend Detection
Q:
Why is macrobend detection only available in the QUAD and 1310/1550 nm single-mode
M310s?
A: Microbends and macrobends result in excess loss in single-mode bers at longer wavelengths.
Consequently, microbend and macrobend detection is only available by comparing single-mode
traces obtained at 1310 and 1550 nm.
Q:
What is the criteria used by the M310 to detect a micro- or macrobend?
A: A micro- or macrobend event is detected when the loss of a point defect at 1550 nm exceeds
the loss at 1310 nm by 0.2 dB or more.
Q:
If a loss event is detected at 1550 but not 1310 nm, can a micro or macrobend still be
detected?
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