3Com 5104M-FB1, 5102M-FBP, 510M-FBP installation and operation guide Attenuation

Attenuation

It is possible for receivers to receive too much light when:

❑Using 85/125 and 100/140 micron fiber cables

❑Ports are close together on a link

Receivers can also receive too much light on 62.5 micron fiber and High power on the 10BASE-FB Modules when:

❑Connecting to an 10BASE-FB product (6.25 dB loss required)

❑Connecting to another 10BASE-FB Module (.25 dB loss required) In these two situations, switch the 10BASE-FB Module to Normal power.

In all of the cases listed above, some attenuation is required to prevent this problem. This attenuation is covered by:

❑A moderate link length

❑The fiber optic connectors

Splicing

Many fiber optic installations employ the use of patch panels to manage expansion and topological changes. A typical patch panel consists of a set of female to female bulkhead barrel connectors used to connect male fiber connectors on both sides. The optical power loss through a patch panel therefore includes two connectors and a bulkhead.

If a fiber optic cable breaks, the break is usually fixed by splicing the broken ends together. Use one of the following types of splicing methods:

❑Fusion – A fusion splice usually offers lower power loss, but the fusion equipment is often bulky and costly.

❑Mechanical – A mechanical splice can be conveniently used in the field when a fusion splice is not available. If a repair is made, make sure that the fiber cable still meets the power loss guidelines.

2 - 10 ONline Ethernet 10BASE-FB Module Installation and Operation Guide