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E-6
A
PPENDIX
E: C
ABLING
R
EQUIREMENTS
Refer to Table E-3 for the insertion losses of the fibers themselves. Use
Table E-4, which lists the losses for connectors, cables, and splices, if the
specifications for these components are not available.
Use Table E-3 for fiber-to-fiber connections only, not for power launched
from a transmitter.
Example.
Suppose that a link consisting of one km of 62.5/125 fiber with a
maximum attenuation rating of 1.75 dB/km is transmitting into one km
of 50/125 fiber with a maximum attenuation rating of 3 dB/km. The
fibers are joined using a fusion splice rated at 0.3 dB and the link contains
one in-line ST connector rated at 0.6 dB.
Table E-3
Insertion Losses for Mating Unlike Fiber Types - Transmitting Fiber
Receiving
Fiber Size
Numerical
Aperture
50 µm 50 µm 62.5 µm 85 µm 100 µm
0.20 0.22 0.275 0.26 0.29
50 µm 0.20 0.0 0.4 2.2 3.8 5.7
50 µm 0.22 0.0 0.0 1.6 3.2 4.9
62.5 µm 0.275 0.0 0.0 0.0 1.0 2.3
85 µm 0.26 0.0 0.0 0.1 0.0 0.8
100 µm 0.29 0.0 0.0 0.0 0.0 0.0
Table E-4
Typical Losses for Typical Connectors, Cables, and Splices
Type of Insertion Loss
SC connector .6 dB
ST connector (ceramic) .6 dB
ST connector (plastic) 1.0 dB
ST connector (stainless steel) .7 dB
62.5/125 cable 1.0 to 3.0 dB maximum per km, depending
on cable quality (nominal 2.0 dB)
8/125 cable .5 dB/km (AT&T Lightguide)
Bypass switch (currently not
available in single mode)
2.5 dB maximum
Fusion splice 1 to 3 dB depending on type used (use .3 dB)