“OTDR: This is the essential tool for troubleshooting. Basic units can be helpful for only the
most experienced technicians, while more sophisticated models can enable all technicians to
troubleshoot complex fiber issues and give insight
into every connector and fault on the link,” he said.
Lang said the latest test equipment has
transformed ease of use, citing his company’s
new OTDR with integrated bidirectional averaging. This technology measures a fiber pair in
both directions with a single tester without having to move the tester to the far end, and then it
automatically averages the results as specified
in Standard ANSI/TIA-526-14-B.
“Contamination is the No. 1 cause of failures,”
he said. “Far too many are cleaning fibers with
their shirt or cloths that can actually add or attract
contaminants. Other common mistakes result from
inadequate training. Setting up the tester incor-
rectly before making a loss measurement test can
result in ‘negative loss’ measurements. Using an
OTDR without a ‘tail fiber’ at the far end of the link
makes it impossible for the OTDR to accurately
characterize the final connector in the link.”
Keith Foord, product manager at Greenlee
Communications, said that, as the need for in-
creased bandwidth goes up, fiber optic cabling is
replacing copper wiring because of fiber’s virtu-
ally unlimited bandwidth potential. Fiber is being
used in structured wiring in point-to-point and
FTTx [fiber to anywhere] configurations. In ad-
dition, fiber satisfies the need for a secure data
link because it can’t be tapped into.
Foord said basic tests are for insertion loss
(IL) and return loss (RL) testing. A laser or LED
source is used with an optical power meter to
measure the IL. An OLTS is used to bidirectionally measure IL and RL. OTDRs are used to locate
and document loss locations and magnitude and
locate fault events. Visual continuity testing is
used to locate possible loss locations. Ethernet
testers are used to test how well a fiber link will
support upper layer protocols.
“The most common mistakes made are not
cleaning connectors and using the wrong equipment, such as an OTDR, when an OLTS should be
used,” Foord said. “Using a VFL to perform continuity testing is not a substitute for IL testing.
A VFL should only be used for finding potential
loss locations, not quantifying them.”
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at
The 93XC OTDR is part of the Greenlee
Communications family of fiber equipment.