Mode Conditioning Patch Cord; Installing The Patch Cord - HP J9827A Installation Manual

Mode Conditioning Patch Cord

The following information applies to installations in which multimode fiber-optic cables are
connected to a Gigabit-LX port or a 10-Gigabit LRM port. Multimode cable has a design
characteristic called "Differential Mode Delay", which requires the transmission signals be
"conditioned" to compensate for the cable design and thus prevent resulting transmission errors.
Under certain circumstances, depending on the cable used and the lengths of the cable runs,
an external Mode Conditioning Patch Cord may need to be installed between the Gigabit-LX or
10-Gigabit LRM transmitting device and the multimode network cable to provide the transmission
conditioning. If you experience a high number of transmission errors on those ports, usually CRC
or FCS errors, you may need to install one of these patch cords between the fiber-optic port in
your switch and your multimode fiber-optic network cabling, at both ends of the network link.
The patch cord consists of a short length of single mode fiber cable coupled to graded-index
multimode fiber cable on the transmit side, and only multimode cable on the receive side. The
section of single mode fiber is connected in such a way that it minimizes the effects of the
differential mode delay in the multimode cable.
NOTE: Most of the time, if you are using good quality graded-index multimode fiber cable that
adheres to the standards listed in
a need to use mode conditioning patch cords in your network. This is especially true if the fiber
runs in your network are relatively short.
For 10-Gigabit LRM using OM3 cable (50 μm multimode @ 1500/500 MHz*km), a mode
conditioning patch cord is not required. Other multimode cables may require mode conditioning
patch cords to achieve the LRM maximum distances.

Installing the Patch Cord

As shown in the illustration below, connect the patch cord to the transceiver with the section of
single mode fiber plugged in to the Tx (transmit) port. Then, connect the other end of the patch
cord to your network cabling patch panel, or directly to the network multimode fiber.
If you connect the patch cord directly to the network cabling, you may need to install a
female-to-female adapter to allow the cables to be connected together.
Figure 9. Connecting a Mode Conditioning Patch Cord for Gigabit-LX
Make sure you purchase a patch cord that has appropriate connectors on each end, and has
multimode fibers that match the characteristics of the multimode fiber in your network. Most
important, the core diameter of the multimode patch cord must match the core diameter of the
multimode cable infrastructure (either 50 or 62.5 microns).
Cabling and Technology Specifications, there should not be
Mode Conditioning Patch Cord 31