Fluke Versiv Series - Use a Launch Cord of the Correct Length; Use a Launch Cord that Has the Correct; Connectors

Versiv Series Cabling Certification Product Family
Technical Reference Handbook
638
Use a Launch Cord of the Correct Length
To do an OTDR test on a long fiber, the tester uses wider pulse
widths to increase dynamic range. Wider pulse widths make
wider dead zones, which can hide the first connector and the
fiber at the near end of the link.
To make sure you see measurements for the near end of the link,
use a launch cord that is longer than the dead zone. Table 27
shows examples of minimum lengths of launch cords for typical
links.
Table 27. Minimum Length of a Launch Cord
Use a Launch Cord that Has the Correct
Connectors
One end of the launch cord must have the same type of connector
as the OTDR. The other end must have the same type of
connector and polish as the link. Do not use hybrid patch cords to
connect launch cords to the OTDR or to the link.
An exception is the bi-directional SmartLoop test. For these tests,
you move the OTDR connection from the launch cord to the tail
cord halfway through the test. To decrease wear on the OTDR
connector and help keep it clean, use the short patch cord
Maximum Length of Link (km) Typical Pulse
Width (ns)
Minimum Launch
Cord Length
(meters)
*
1310 nm 1550 nm only
0 to 35 0 to 50 1000 160
35 to 45 50 to 65 3000 400
45 to 50 65 to 75 10000 1000
50 75 20000 2400
* For fiber with typical attenuation ( 0.35 dB/km at 1310 nm;  0.2 dB/km at
1550 nm) and event loss less than 0.8
dB.