About Launch And Receive Fibers - Fluke DTX-1800 Technical Reference Handbook

About Launch and Receive Fibers

Launch and receive fibers let the tester measure the loss
and reflectance of the first and last connectors in the
cabling. Without launch and receive fibers, no backscatter is
available before the first connector and after the last, so the
tester cannot measure the connectors' characteristics.
If the first or last connection in the cabling is bad, and you
do not use launch and receive fibers, the OTDR test may
pass because it does include measurements from the bad
connection.
Overall Loss and Length include the loss and length of the
launch and receive fibers, unless launch compensation was
enabled during the test.
Fluke Networks recommends that you use launch and
receive fibers. You should also use launch compensation to
remove the effects of these fibers from the OTDR
measurements.
Avoid using hybrid patch cords to connect to the
cabling under test. Connect the launch and receive
fibers directly to the cabling under test, using a
launch fiber with the appropriate connectors. This
provides the best view of the connectors at the
ends of the cabling. Hybrid launch fibers with
various connector styles are available from Fluke
Networks.
Note
Setting Up for OTDR Testing
W
When testing links with APC (angled physical
contact) connectors, use only launch fibers with
APC connectors on the ends connected to the link,
and UPC connectors on the ends connected to the
testers. Connecting non-APC connectors to the
link will produce large reflections on the OTDR
trace and may invalidate measurements.
Compensating for Launch and Receive Fibers
The launch compensation function marks the end of the
launch fiber and the beginning of the receive fiber on
OTDR traces and labels these events in the event table. It
also removes these fibers' losses, lengths, and attenuation
coefficients from overall OTDR results. The losses of the
connections at the launch and receive fibers are not
removed from the results.
Using the OTDR Module
Caution
7
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