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RE: Re[2]: (SSIG) Taking the winning route

Dear Hailing:

The OFL bandwidth of 500 MHz-km at 1300 nm is not realistic, because laser
sources are not OFL launch.  The effective bandwidth is much higher than 500
MHz-km. Furthermore, the normal 62.5 um MM fiber can provide bandwidth of
more than 1 GHz-km.

However, the DMD, caused by imperfection of the refractive index profile,
can reduce bandwidth to less than 1 GHz-km.  These defected DMD fibers can
be corrected by adding a mode conditioner, off-set, or Donut type.  If these
devices become a mass production product, I believe, the unit price will be
in $15 to $30 range.

Only a very small portion of the installed MM fiber may need a mode
conditioner.  The users are not recommended to use it, unless needed.


Edward S. Chang
NetWorth Technologies, Inc.
Tel: (610)292-2870
Fax: (610)292-2872

-----Original Message-----
From: owner-stds-802-3-hssg@xxxxxxxx
[mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of hzhong@xxxxxxxxxxxx
Sent: Thursday, April 13, 2000 10:50 AM
To: NetWorthTK@xxxxxxx; giorgio@xxxxxxxxxx; david_cunningham@xxxxxxxxxxx
Cc: rtaborek@xxxxxxxxxxx; stds-802-3-hssg@xxxxxxxx
Subject: Re[2]: (SSIG) Taking the winning route


I agree that it is possible the length can go longer than the standard has
specified on 62.5um at 1300nm in many cases. However, we need to be careful
our assumptions. For example, are you assuming that both offset patchcord
WDM to be used at the same time? That is a guaranteed to be expensive and a
of hassle for the field tech.

Hailing Zhong
Lucent Technologies
Member of Technical Staff

____________________Reply Separator____________________
Subject:    Re: (SSIG) Taking the winning route
Author: <NetWorthTK@xxxxxxx>
Date:       4/12/00 9:43 PM

Dear Giorgio:

How did you get 280 meter to make shortage of 20 meter out of 300 meter
total,  then claim it is failure.  I do not believe the actual optical link
design can be that simplified.  The real optical link does not behave as a
step function, rather a gradual change.

The fiber distance is very complex trade off among fiber effective
transmitter rise time, receiver bandwidth, bit error rate, and power.

Even the new fiber cannot guarantee without DMD problem which will change


Ed Chang

<<  agree with you the Gigabit Ethernet model has been proven to be robust
 and I congratulate with the work that has been done.
 Based on a straightforward extension of that model, a 3.125 Gb/s link at
 can go approximately 280 m on installed MMF (62.5um 500MHz km).
 This is below the objective of 300 m and does not consider additional
 potential impairments introduced by the WDM process.