[10GBASE-T] RE: EMI Discussion
Hello all,
Since my earlier post with attachment could not be forwarded, I have posted
the attachment onto the CX4 site at the following URL;
http://www.ieee802.org/3/ak/MLT3_2ndOrder.jpg
It shows the PSD reduction that is likely to exist on a CAT5(e) or CAT6
cable plant due to natural filtering in the magnetics, PCB and device pads.
Since the energy above 100MHz is really not necessary for data recovery, it
could be much lower.
My point was that 10GBASE-T (or 2.5GBASE-T for that matter!) operating on
UTP will have to address the possible imbalance and other anomalous
impairments that could impact FCC/EN compliance specs at frequencies between
100MHz and 450MHz because vendors of infrastructure equipment may not have
tested in that region. George Z has pointed me to their presentation which
indicates acceptable EMI performance and I am waiting for one of his
engineers to provide more detail with regard to the breadth and depth of
testing that was done to confirm that presentation.
Best Regards,
Dan Dove
HP ProCurve Networking
> -----Original Message-----
> From: DOVE,DANIEL J (HP-Roseville,ex1) [mailto:dan.dove@hp.com]
> Sent: Wednesday, July 30, 2003 9:29 AM
> To: 'Joseph Babanezhad'; stds-802-3-10gbt@ieee.org
> Subject: RE: [10GBASE-T] PAR and 5 critters
>
>
>
> Hi Joseph,
>
> Thank you for the clarification. I mis-understood your
> presentation in that
> I thought you were comparing the PSD of 100MB MLT-3 with that
> of 1000MB
> PAM-5, and then 10G (others) to show similarity of the PSD
> energy above
> 100MHz. That explains to me why the MLT-3 shape appeared the
> way it did. My
> calc's showed a different shape, but similar in slope if the
> MLT-3(100) was
> unfiltered.
>
> As my attachment showed, MLT-3/100 and PAM5/1000 are likely to have
> substantially lower energy above 100MHz which means that EMI
> performance of
> CAT5(e) or CAT7 cable plants may not have really been stressed to meet
> FCC/EN compliance requirements as they would to perform with higher
> differential PSDs that would exist using 10G line codes.
>
> I was wondering if someone has done a study of installed base
> components to
> confirm that we are not completely prohibited by that
> installed base for
> using the frequencies and levels that are being proposed?
> Unless we want to
> rule UTP out completely, I think such a study is necessary to
> ensure that
> the PSD under discussion is going to meet FCC requirements.
>
> I remember that 1000BASE-T had a similar hurdle to keep its
> spectrum ~under
> 100BASE-T. I believe we can lower that hurdle, but really
> need to understand
> just how much.
>
> Regarding my attachment, maybe Brad can post to to the 10G
> website as a
> contribution? It showed your PSD graphs, and then an MLT3 PSD
> with/without
> 2nd order filtering which demonstrates the large reduction in
> energy above
> 100MHz that is going to exist in a normal implementation due
> to parasitic
> package elements and magnetics.
>
> Dan
>
> > -----Original Message-----
> > From: Joseph Babanezhad [mailto:jobaba@platolabs.com]
> > Sent: Tuesday, July 29, 2003 2:18 PM
> > To: stds-802-3-10gbt@ieee.org
> > Subject: RE: [10GBASE-T] PAR and 5 critters
> >
> >
> >
> > Dan,
> >
> > My January 2003 presentation to IEEE 10GBASE-T SG
> >
> > http://www.ieee802.org/3/10GBT/public/jan03/babanezhad_1_0103.pdf
> >
> > assumes that all the line-signals considered (MLT3, PAM5-to-PAM33)
> > have the same minimum pulsewidth of 800ps. That is why all of them
> > have notches at 1.25GHz and 2.5GHz.
> >
> > If you were to review my March 2003 presentation
> >
> > http://www.ieee802.org/3/10GBT/public/mar03/babanezhad_1_0303.pdf
> >
> > here various line signals considered have different minimum
> > pulsewidth in order for all of them to achieve 2.5 Gb/s data rate.
> > The minimum pulsewidth for both MLT3 and PAM5 is 800ps. For MLT3
> > and PAM5 their notches are still at 1.25GHz and 2.5GHz while for
> > PAM9-to-33 they are at different frequencies. When comparing
> > MLT3 and PAM5's frequency spectrums it becomes clear that MLT3
> > shows considerable peaking around pass-band and notch frequencies.
> >
> > There was no additional filtering, such as TX pulse
> shaping, included
> > in deriving these frequency spectrums.
> >
> > Regards,
> >
> > Joseph N. Babanezhad
> > Plato Labs.
> >
> > -----Original Message-----
> > From: "Booth, Bradley" <bradley.booth@intel.com>
> > To: <stds-802-3-10gbt@ieee.org>
> > Date: Tue, 29 Jul 2003 11:54:22 -0700
> > Subject: RE: [10GBASE-T] PAR and 5 critters
> >
> > >
> > > Forwarded for Dan Dove without attachment... Dan, please
> > give the URL
> > > for the presentation as our website doesn't accept attachments.
> > >
> > > Thanks,
> > > Brad
> > >
> > > -----Original Message-----
> > > From: "DOVE,DANIEL J (HP-Roseville,ex1)" <dan.dove@hp.com>
> > > To: "'Sterling Vaden'" <sterlingv@bellsouth.net>
> > > Cc: stds-802-3-10gbt@ieee.org
> > > Subject: RE: [10GBASE-T] PAR and 5 critters
> > > Date: Tue, 29 Jul 2003 11:17:53 -0700
> > >
> > > Hi Sterling,
> > >
> > > I have been an outsider to the study group work, so please
> > excuse me if
> > > I am
> > > bringing up an issue that has already been dealt with, but as I
> > > understand
> > > it the current proposals for coding rely upon a spectrum of
> > > 400MHz.
> > > It
> > > is
> > > possible that companies manufacturing cable system infrastructure
> > > equipment
> > > like patch panels, wall jacks, and even the cable itself
> > have qualified
> > > their products for FCC and EN compliance based upon
> > measurements done
> > > with
> > > equipment that only uses <100MHz spectrum like 100BASE-T or
> > 1000BASE-T.
> > > That
> > > said, the balance requirements for such equipment may never
> > have been
> > > stressed at frequencies above 100MHz for longitudinal
> > balance, and so
> > > the
> > > installed base of cable systems may have issues with EMI
> > compliance if
> > > someone were to begin running equipment with a PSD that
> > produces large
> > > energy above 100MHz on those systems.
> > >
> > > Has any work been done to characterize this issue? I found a
> > > presentation by
> > > Joseph Babanezhad but don't think he applied a full
> analysis in the
> > > sense
> > > that it appears he did not allow for natural filtering of
> the output
> > > PSD
> > > by
> > > device capacitance and magnetics on the MLT-3 PSD. Check out the
> > > attachment.
> > > Clearly MLT-3 and PAM-5 (100 and 1000 speeds) can operate without
> > > energy
> > > above 125MHz and most implementations limit energy above that
> > > frequency.
> > > I
> > > believe the 10G designs will require substantially higher
> > energy than
> > > those
> > > technologies in the region 100MHz < f > 400MHz.
> > >
> > > Again, please excuse me if this has been addressed. Just
> point me to
> > > the
> > > data.
> > >
> > > Regards,
> > >
> > > Dan Dove
> > > 802.3 member
> > >
> > > -----Original Message-----
> > > From: Sterling Vaden [mailto:sterlingv@bellsouth.net]
> > > Sent: Tuesday, July 29, 2003 6:43 AM
> > > To: stds-802-3-10gbt@ieee.org
> > > Cc: stds-802-3-10gbt@ieee.org
> > > Subject: Re: [10GBASE-T] PAR and 5 critters
> > >
> > >
> > > OK, I'll bite,
> > >
> > > I think it has been "shown" that for the purposes of the PAR and 5
> > > critters,
> > > 10G will work over the following:
> > >
> > > ISO Class F without ammendment.
> > > ISO Class E (or Cat6) screened or SSTP (with extended
> > limits to 500 or
> > > 625
> > > MHz) extended limits TBD by ISO or TIA
> > > (note that Class D and Class E screened (overall shield) and SSTP
> > > (individually shielded pairs) are commonly installed in
> > Europe, so this
> > > is
> > > not a "fantasy cable". Screened cabling is also specified by TIA)
> > > ISO Class E (or Cat6) UTP to 50 meters (with extended
> > limits to 500 or
> > > 625
> > > MHz) extended limits TBD by ISO or TIA
> > >
> > > ISO Class D (Cat5e) Screened? Perhaps up to 80 meters, but
> > this is grey
> > > area.
> > > ISO Class D (Cat5e) UTP? Perhaps up to 40 meters,
> > >
> > > For ISO Class D (Cat5e) there is a basic problem in that
> the cabling
> > > standards groups are unwilling to standardize (create
> limits) beyond
> > > 100
> > > MHz, or expend further work on the cabling besides
> measure it. This
> > > poses a
> > > very real difficulty in specifying a protocol that relies upon
> > > performance
> > > beyond that specified by the cabling standard. (ask Geoff
> Thompson)
> > > Cabling
> > > manufacturers may decide to forego warranting their cabling
> > systems for
> > > such
> > > a protocol.
> > >
> > > Also, for the time being, lets pretend that alien crosstalk field
> > > testing
> > > does not exist (it doesn't). Also lets pretend that alien
> crosstalk
> > > mitigation techniques (all, retrofit and new cable
> designs) for the
> > > moment
> > > do not exist. These are considerations for the task group.
> > >
> > > Some may also contend that the protocol will run on longer
> > lengths of
> > > Cat5e
> > > and Cat6 UTP. If so, that is fine, but it is a matter of
> > dispute, and
> > > therefore cannot be considered. This is also a
> consideration for the
> > > task
> > > group.
> > >
> > > At the Plenary, on the last day we heard the PHY vendors
> > backpedaling
> > > on
> > > their previously stated opiniion that it would run on Class
> > F. If that
> > > is
> > > the case, and they insist on this position, then the
> > project is dead.
> > > Therefore I propose that there must be an agreement that
> > the protocol
> > > will
> > > run on at least Class F cabling to 100 meters, or we need to start
> > > over.
> > > If
> > > we can agree on that, then we can move forward to
> consider the other
> > > cabling
> > > classes.
> > >
> > > Sterling Vaden
> >
>