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*To*: <hbuelow@xxxxxxxxxx>, <stds-802-3-hssg@xxxxxxxx>*Subject*: RE: PMD Equalization*From*: "Vipul Bhatt" <vipul.bhatt@xxxxxxxxxxx>*Date*: Tue, 19 Sep 2000 18:42:26 -0700*Importance*: Normal*In-Reply-To*: <NEBBKCMMKLHMMAKPFMBLGEFMCAAA.cmadden@xxxxxxxxxxx>*Reply-To*: <vipul.bhatt@xxxxxxxxxxx>*Sender*: owner-stds-802-3-hssg@xxxxxxxx

To: Those members of P802.3ae who have information about fiber design and manufacturing. Please help me understand some issues. 1. If I look at all the singlemode fiber in the ground today, is it fair to say that they can be put into two buckets - one with low PMD of about 0.1 ps/sqrt(km), and one with high PMD, say, several times larger? If yes, how much bigger is one bucket compared to the other? 2. Do those buckets correlate with dates of shipment - say, after 1992 and before 1992? 3. Do those buckets correlate with application - say, Undersea cable and Metro/Access fiber? 4. Using 0.5 ps/sqrt(km) as an example, can I interpret it to be the standard deviation of a distribution, therefore the peak-to-peak value may be several times higher? If this were a Gaussian distribution (I know it's not), I would then take 7 times sigma = 3.5 ps/sqrt(km) as its peak-to-peak value. Therefore, for a 49 kilometer link, the PMD peak-to-peak value will be 3.5*sqrt(49) = 24.5 ps. Is my understanding correct? 5. In some fiber data sheets, I see a note that says: "...fiber specification supports emerging network design requirements for a 0.5 psec/sqrt(km) maximum PMD." Where is this design requirement documented? Thanks, Vipul vipul.bhatt@xxxxxxxxxxx (408)542-4113 =========================== > -----Original Message----- > From: owner-stds-802-3-hssg@xxxxxxxx > [mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Chris Madden > Sent: Tuesday, September 19, 2000 10:53 AM > To: hbuelow@xxxxxxxxxx; stds-802-3-hssg@xxxxxxxx > Subject: PMD Equalization > > > > Henning, > > In your presentation to the 802.3ae September Interim on circuit > implementation > of a polarization mode dispersion (PMD) equalizer you > showed pulse responses > for 100km lengths of single mode fiber. Did you also > characterize the PMD of > these fibers using an interferometric method [ref. 1] or > the widely-used > Stokes > Parameter Method [ref. 2]? Can you give some additional > information on the > type > of fiber used in this work? The magnitude of PMD seems > larger than expected. > > Thank you, > > Chris > > [1] Namihira, Y. and Wakabayashi, H., "Fiber Length Dependence of > Polarization > Mode Dispersion Measurements on Long-Length Optical > Fibers and Installed > Optical Submarine Cables", J. Opt. Communications, > 12, 1, p. 2-9 (1991). > > [2] Poole, C. D., et. al., "Polarization Dispersion and > Principal States in > a > 147-km Undersea Lightwave Cable", J. Lightwave > Tech., v.6, no.7, p. 1185- > 90 (1988). > > ********************************************************** > ****************** > ** > Christopher J. Madden, Ph.D. 3900 > Freedom Circle, Suite > 200 > Principal Engineer/Scientist > Santa Clara, CA > 95054 > Fiber-Optic Data Communications Phone: > 408.565.6857 > Tripath Technology Inc. Fax: > 408.565.6850 > http://www.tripath.com > cmadden@xxxxxxxxxxx > ********************************************************** > ****************** > **

**References**:**PMD Equalization***From:*Chris Madden

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