Manual

19
Test: Attenuation Measurement
An insertion loss measurement for fiber acceptance test during onsite build is a non-destructive method and is used
to measure the attenuation across a fiber, a passive element, or the entire optical link. This is often required where
install phases do not have active equipment provisioning onsite or where cable infrastructure and equipment
installs are performed by separate teams. Measure the output from the source fiber and a reference fiber directly.
Then, obtain a measurement with the fiber under test added to the system. The difference between the two results
provides the attenuation of the fiber.
Attenuation Measurement (optical link loss) on optical components or fiber optic links (for example, fiber
connectors, cable assemblies, and installed fiber optic links) are acquired by measuring the relative power level (dB)
at the far end of the link or device under test.
Relative Power Level (attenuation measurement) is the amount of power lost (attenuated) by the optical
link being tested, measured in dB. The source of this power is typically a handheld optical light source. This test
determines whether the optical link is constructed properly, either as a qualification test or when troubleshooting
the fiber cabling.
NOTE: It is common practice to make a simple insertion loss measurement using an optical light source (OLS) at the BBU and an OPM at the RRU to check the link loss. However, in order
to minimize the operations and tools required at the remote end, a loopback device is often used to enable measuring the loss of the entire channel. Both methods are described below.
To measure attenuation, you must:
. Get a reference measurement.
. Get an attenuation measurement.
NOTE: Loss testing of single-mode fiber links is specified in ANSI/TIA/EIA-526-7 and ISO/IEC-TR-14763-3.
Loss testing of multimode fiber links is specified in ANSI/TIA/EIA-526-14A and ISO/IEC-TR-14763-3.
TEST