3Com DUA3700-0BAA04 manual Example, Type of Insertion Loss

E-6APPENDIX E: CABLING REQUIREMENTS

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.

Table E-3Insertion Losses for Mating Unlike Fiber Types - Transmitting Fiber

Receiving	Numerical
Fiber Size	Aperture	50 µ m	50 µ m	62.5 µ m	85 µ m	100 µ m
		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-4Typical 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	2.5 dB maximum
available in single mode)
Fusion splice	1 to 3 dB depending on type used (use .3 dB)

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.