RE: [SI-LIST] : FCAL DB9 cable shield

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From: Jeremy Stover (jeremy.stover@lsil.com)
Date: Mon Jan 10 2000 - 11:27:34 PST


Can someone point me to the info for signing up on the emc-pstc list
server
referenced below?

Thanks

Jeremy Stover
LSI Logic
3718 N. Rock Road
Wichita KS 67226
Jeremy.Stover@lsil.com
316-636-8426

                -----Original Message-----
                From: Knighten, Jim L
[mailto:JK100005@exchange.SanDiegoCA.NCR.COM]
                Sent: Thursday, November 18, 1999 10:58 AM
                To: si-list@silab.eng.Sun.COM
                Subject: RE: [SI-LIST] : FCAL DB9 cable shield

                Chris,

                Ah! This is the fun part of EMI.

                You correctly characterize my underlying assumption , i.e.,
the noise source is imbalance in the differential signal within the
cable.
Over the past couple of years, some have termed this "signal-induced"
EMI,
rather than the EMI source that is external to the cable and merely
"hitches
a ride" on the cable shield. I can point you to at least 2 papers in
the
August 1999 IEEE EMC Symposium and one in 1998.

                In my experience at NCR, with the FC applications that we
have, this has always been the dominant problem. I must say that we
spend
a lot of energy designing our boards to be quiet.

                Of course there is one solution that eliminates the ground
loop noise problem (Ron's opinion). That is the use of fiber optics
instead of copper cables. Be warned, however, that this does NOT
eliminate
the EMI problem.It merely changes its nature. I have stated in another
thread that a myth of modern technology is that fiber optics are
EMI-proof. If
you log onto the emc-pstc list server, you will find that modern high
data rate fiber optics present huge EMI challenges because the
electronics
used are so noisy and connectors are so poorly designed for EMI
containment.

                Jim
                ________________________________________________________
                Dr. Jim Knighten e-mail:
Jim.Knighten@SanDiegoCA.NCR.com
                <mailto:Jim.Knighten@SanDiego.NCR.com>
                Senior Consulting Engineer
                NCR
                17095 Via del Campo
                San Diego, CA 92127 http://www.ncr.com
<http://www.ncr.com>
                Tel: 858-485-2537
                Fax: 858-485-3788

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