Manual

15
Optical Time Domain Reflectometer (OTDR) Testing
An OTDR is a fiber optic tester for characterizing fiber and optical networks. It detects, locates, and measures
events at any location on the fiber link. The ability of an OTDR to characterize a fiber is based on detecting small
signals that are returned back to it in response to the injection of a large signal, a process similar to
radar technology.
One of the main benefits of an OTDR is that it enables complete fiber characterization from only one end of the
fiber. The resolution of an OTDR is between 4 centimeters and 40 meters. It generates geographic information
regarding localized loss and reflective events, providing technicians with a pictorial and permanent record of a
fiber’s characteristics that can be used as the fiber’s performance baseline.
Tier 2 certification uses an OTDR to:
y Provide a visual look at the network using an OTDR trace
y Provide results in a schematic map for immediate diagnosis of problems understandable at any skill level
y Identify issues before a link is turned up
y Locate faults such as breaks and macrobends
y Measure the return loss of an installation
y Differentiate how each event contributes to link loss
y Provide the overall link loss (with proper launch cable settings)
y Provide a birth-certificate report of the network condition on install
TEST
Example of an OTDR trace