Calculating Insertion Losses For Unlike Fibers - 3Com CoreBuilder 2500 Getting Started Manual

Table D-2 Alternate Multimode Fiber Types
Core (mm) Cladding (mm)
50 125
50 125
85 125
100 140
If you are using fiber with a diameter of 50 mm and
have 3Com equipment at both ends of the link,
substitute 8 dB for the maximum attenuation in
Table D-1. If 3Com equipment is only at one end,
substitute 6 dB for the maximum attenuation value.
If you are using equipment at the end of a link from
a vendor other than 3Com, you must perform a
separate loss budget analysis. Contact the vendor(s)
of your other equipment for values to use in your
analysis.

Calculating Insertion Losses for Unlike Fibers

If unlike fibers are mated in the cable plant,
calculate insertion losses to be certain that the cable
plant does not exceed the maximum attenuation
value. To calculate the insertion loss, consider the
types of fiber in the cable plant and the connectors
or splices used to join them. Compare the result to
the maximum attenuation value listed in
If the result is greater than the value in the table,
use only like fibers in your cable plant.
Numerical Aperture
0.20
0.22
0.28
0.29
Table D-1.
Multimode Fiber Standards
Refer to Table D-3 for the insertion losses of the
fibers themselves. Use
losses for connectors, cables, and splices, if the
specifications for these components are not
available.
Use Table D-3 for fiber-to-fiber connections only, not
for power launched from a transmitter.
Table D-3 Insertion Losses for Mating Unlike Fiber Types
Transmitting Fiber Size
50
mm
Receiving Numerical
Fiber Size Aperture 0.20
50 mm
0.20 0.0
50 mm
0.22 0.0
62.5 mm
0.275 0.0
85 mm
0.26 0.0
100 mm
0.29 0.0
D-3
Table D-4, which lists the
50 62.5 85 100
mm mm mm mm
0.22 0.275 0.26 0.29
0.4 2.2 3.8 5.7
0.0 1.6 3.2 4.9
0.0 0.0 1.0 2.3
0.0 0.1 0.0 0.8
0.0 0.0 0.0 0.0