Optical Insertion Loss; Tools: Ona-800 Otdr With Optical Source (Cw) And Usb Optical Power Meter (Mp-60/80) - Viavi OneAdvisor 800 Series Manual

The picture below shows as example of the LC Duplex connector at the RU end of the tower top jumper. A
duplex coupler can be used to then connect a simplex fiber as a loopback.
Once Continuity is proven with a VFL you can move on to an Optical Insertion Loss Measurement or an
OTDR Measurement.
5.4

Optical Insertion Loss

This is a measurement of the total optical power loss from the beginning to the end of the fiber system. In
a tower or rooftop site during construction, this would typically be from the bottom, to the top, through a
loopback cable or device, and back to the bottom. This speeds up and simplifies the test by keeping the
Source and Meter at ground level. On a 12-pair hybrid, this also cuts the test count from 24 to 12. This
step comes immediately after IBYC and creating the loopback and proving continuity with the VFL (see
above). However, if an OTDR is available, skip the Optical Insertion Loss test because a system loss
expressed in dB is one of the results that an OTDR provides. Doing both tests would be redundant. Use the
Insertion Loss Test as part of a spot check at the warehouse or on the ground before hoisting. The use of an
OTDR test is recommended for final close-out. The OTDR provides the system loss information as well as
the per event reflectance and per event loss information required.
Most Operators expect a round trip Insertion Loss (IL) value to be less than 3 dB (half power loss)
Measurement
Path loss end to end
5.4.1 Tools: ONA-800 OTDR with Optical Source (CW) and USB Optical Power Meter (MP-
60/80)
This test has 2 steps.
1) (Left picture below) As always, IBYC. Then the Light Source and the MP-60/80 Power Meter needs
to be connected to each other using the clean test leads that will be used in the actual test. Use
1310 nm for Single Mode Fiber. Regardless of the absolute power from the source (in dBm) the
Power Meter is referenced to 0 dB. This also negates any losses from the test leads themselves.
2) (Right picture below) Now the Light Source and Power Meter are connected to the system under
test using the same test fibers that have been referenced out. The loopback established in the
Continuity Test earlier is still in place. Read the value on the power meter. It will be expressed in
Passing Criteria
Less than 3 dB of loss (< -3 dB)
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