1.What is a Mode Conditioning Patch Cord?

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This
special fiber patch cord is a duplex multimode patch cable that has a small
length of single mode fiber at the start of the transmission length. It is
designed to solve the technical issue involved in using single mode equipment
on the existing multimode cable plant. Mode conditioning fiber patch cord aims
to drive the distance of installed fiber plant beyond its original intended
applications, as well as to improve data signal quality.

 

Optical
Mode Conditioners provide a convenient and reliable method of connecting
multimode fiber plants with 1000Base- LX based transmission equipment compliant
with IEEE 802.3 standards. Mode conditioners provide a method of offsetting a
single-mode fiber core with a corresponding multimode fiber. This calibrated
offset reduces a phenomena called differential mode dispersion, or DMD, which
can cause the transmitting laser pulse to spread out and merge into neighboring
pulses creating bit errors in the transmission signal.

 

Mode
conditioners are built in the form of a simple duplex patch cable, so they can
easily be installed in a system without the need for additional components or
hardware. Their length can range from one meter and up to support virtually any
network topography.

 

The
need for this patch
cord is due to the single-mode launch nature of the -LX (1300nm)
transceiver modules used for Gigabit Ethernet. These modules have to operate
for both single-mode and multimode fibers. Launching a single-mode laser into
the center of a multimode fiber can cause multiple signals to be generated that
confuse the receiver at the other end of the fiber. These multiple signals,
caused by Differential Mode Delay (DMD) effects, severely limit the cable
distance lengths for operating Gigabit Ethernet. A mode conditioning patch cord
eliminates these multiple signals by allowing the single-mode launch to be
offset away from the center of a multimode fiber. This offset point creates a
launch that is similar to typical multimode LED launches.

 

Things
to know when using mode conditioning cables to patch an existing multimode
cable plant to your Gigabit LX equipment.

 

Usually
used in pairs, mode conditioning cables usually require a MC cable at each end
to connect the equipment to the cable plant. The only reason to order an odd
number of mode conditioning cables is to have a spare on hand.

 

If
your Gigabit LX switch is equipped with SC or LC connectors, please be sure to
connect the yellow leg (single-mode) of the cable to the transmit side, and the
orange leg (multimode) to the receive side of the equipment. It is imperative
that this configuration be maintained on both ends. The swap of transmit and
receive can only be done at the cable plant side.