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Your 3PMD Proposal




Del and Piers, your presentation 
(http://grouper.ieee.org/groups/802/3/ae/public/may00/hanson_1_0500.pdfon) for 
a proposed set of three PMD's includes 1310 WWDM, but not 850 WWDM.  According 
to slide #6  "Comparison of PMD Technologies" in the presentation by Jim Tatum 
(http://grouper.ieee.org/groups/802/3/ae/public/may00/tatum_1_0500.pdf),  it 
looks like the only advantage of 1300  WWDM over 850 WWDM is that it can reach 
lengths up to 300m, compared to 100m for 850 WWDM.  Also, 1300 WWDM can operate 
up to 10Km on SMF, but your proposed 1300 serial PMD looks like a better 
solution at 10Km because of its lower cost.

According to the referenced slide, 850 WWDM is half the cost of 1300 WWDM and 
can reach lengths up to 550m on the new 50um fiber with a bandwidth of 
2000MHz*km for 850nm.  Based on this information, it looks like the only 
advantage of using 1300 WWDM over 850 WWDM is that it can reach 300m on 
installed 62.5um fiber.

Is this analysis correct and, if so, do you feel that the extra length achieved 
by 1300 WWDM on installed MMF is worth the extra cost?

Thanks,

Larry

Lawrence J. Rennie
National Semiconductor Corporation
Calabasas, CA.
larry.rennie@nsc.com
818 880 2720