2-11
IM AQ7280-01EN
Optical Pulse Measurement (OTDR)
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Index
If you do not set the correct backscatter level, the return loss and total return loss measurements will
be incorrect.
On the AQ7280, you can select the reference pulse width for the backscatter level (see section 3.2).
The selectable range of backscatter levels vary depending on the reference pulse width.
1 µs: The range is –10.00 to ‒64.99.
1 ns: The range is ‒40.00 to ‒94.99.
The AQ7280 has the following preset backscatter levels that correspond to each wavelength.
Wavelength
1 μs Pulse Width
1 ns Pulse Width
850 nm
–37 dB
–67 dB
1300 nm
–44 dB
–74 dB
1310 nm
‒50 dB
‒80 dB
1383 nm
‒51 dB
‒81dB
1490 nm
‒52 dB
‒82 dB
1550 nm
‒52 dB
‒82 dB
1625 nm
‒53 dB
‒83 dB
1650 nm
‒53 dB
‒83 dB
Event Search Conditions
• Splice Loss
If a splice loss that exceeds the specified threshold occurs, it is detected as an event.
The range is 0.01 dB to 9.99 dB.
• Return Loss
If a return loss that is less than or equal to the specified threshold occurs, it is detected as an
event. The larger the reflection, the smaller the return loss, so events (reflections) are detected
when the return loss is less than or equal to the threshold.
The range is 20 dB to 70 dB.
• End of Fiber
If a reflection that exceeds the specified threshold occurs, it is detected as the end of the optical
fiber cable (Fresnel reflection).
The range is 3 dB to 65 dB.
• Splitter Search
ON: Losses (reflections) that exceed optical splitter loss are displayed as optical splitters.
The threshold at the end of the fiber is automatically set to its maximum value.
OFF: Losses (reflections) that exceed splitter loss are displayed as normal events.
• Splitter Loss
Events whose loss exceeds this value are assumed to be optical splitters.
The range is 1 dB to 20 dB.
• Launch Fiber Setting
Using the
rotary knob
and
ENTER
, set Launch Fiber Setting to
Setup[OFF]
or
Setup[ON]
. The
following screen appears.
Set the start event (None, 1, 2).
Set the end event (None, 1, 2).
When you connect a launch fiber cable to avoid near-end dead zones, you can set the launch
fiber cable events (start point and end point) so that the event information in the launch fiber
section is excluded from the analysis conditions.
2.1 Setting the Measurement and Analysis Conditions
