Comments from Sterling Vaden:
DOVE,DANIEL J (HP-Roseville,ex1) wrote:
Hi Brad,
I think you meant to say "Task Force" down there. Did you mean Study group?
Yes I agree that meeting FCC A is a good objective that would drive the
investigation of this issue to completion.
I agree that that is a good objective
My only conundrum on this issue is understanding the balance between "broad
market potential" which I believe depends upon CAT-5e and CAT-6 cables and
"technical feasibility" which I believe depends upon some
assurance that a high-speed line code running at 833Mbd will not by its
nature violate FCC requirements on UTP components that were not designed for
that frequency range.
I think that keeping CAT-5e and CAT-6 cables as an objective is the right
approach, so that leaves us to gain some confidence in being able to obtain
FCC compliance on those cables.
If we have the objective to run on Cat 5e and Cat6 cables, then we
should formalize that objective. Right now, it just says Class F and
lower categories with some ammendments.
The amount of data required
to do that is substantially below the amount required to complete the spec.
I think that limiting the scope of the investigation to what I had discussed
earlier, obtaining market data to understand which components
are broadly installed, then doing some testing on those components is
sufficient to complete those objectives.
Testing should be done on installed channels. Preferrably on stuff
really installed, much of which is not and has never been tested in a
channel (end-to-end) configuration.
Another possible angle would be to restrict the application to patch cords
only for data center/wiring closet applications and if that gets broad
enough capture of the market, move forward and expand the study down the
road to include x-connects, patch-panels and wall jacks. I have very low
concern about the cable itself, its those darned connectors that give me
concerns. This latter approach, if the marketing folks believe it will be
viable, would substantially reduce my concerns about EMI feasibility at this
stage.
This really confuses the scope, I believe. Patch cords are tested using
connectors, so this does not get away from the connector issues. In the
standards, patch cord maximum length is not unambiguously specified.
They are also only qualified for NEXT and return loss. The radiated
emissions from connectors, however important, has not been shown to be
the major contributor to ANEXT. ANEXT and FCC emissions levels probably
have a direct relationship.
Sterling
Dan
Dan,
I agree that the Study Group could use more breadth of data,
considering
that both EMI measurements I found (jones_2_0103 and
powell_1_0303) have
been based on unscreened Cat5e cabling. I also agree that the Study
Group should take EMI into consideration in selecting
proposals to adopt
for a first draft.
The question I have is about the best approach. Personally, I believe
that creating an objective to "meet FCC Class A requirements" is what
the Study Group needs at this point in time. That would
place a burden
on the Study Group to evaluate our cable type and reach objectives
^^^^^^^^^^^
Task Force
relative to EMI compliance.
Do you agree with that approach?
Thanks,
Brad
-----Original Message-----
From: DOVE,DANIEL J (HP-Roseville,ex1) [mailto:dan.dove@hp.com]
Sent: Wednesday, August 13, 2003 6:22 PM
To: Booth, Bradley; stds-802-3-10gbt@ieee.org
Subject: RE: [10GBASE-T] RE: EMI Discussion
Hi Brad,
I think the point of "enough data" is subjective and up to the Study
group
to determine.
While I have reviewed a number of the presentations via the
web, I have
not
given it nearly as much study as the members of this SG, so I don't
presume
to be as qualified to make that judgement as they are. I have
seen some
data
indicating areas of concern <Cobb July03,Powell May03>, and I have
reviewed
the methods and data used to generate the CFI slide as discussed in my
earlier email, and from that I believe we need more breadth
in the data
to
understand what percentage of CAT-5e and CAT-6 cables will be
supportable
for EMI compliance.
A lot of the data provided at the URL you reference is
focused on signal
integrity, not EMI. This is fine because there are a lot of signal
integrity
challenges to deal with. I think the priority is OK, but am suggesting
broader EMI investigation for the UTP solutions.
I won't be at the September meeting, so I was providing my
recommendation to
the SG with the hope that some are inspired to present broader based
data,
and all will evaluate that data and apply their judgement to
the issue.
Regards,
Dan
-----Original Message-----
From: Booth, Bradley [mailto:bradley.booth@intel.com]
Sent: Wednesday, August 13, 2003 1:24 PM
To: stds-802-3-10gbt@ieee.org
Subject: RE: [10GBASE-T] RE: EMI Discussion
I know I don't have the depth of experience that Dan and
Geoff have with
802, but I thought it is of interest that ISO/IEC 11801 1st
edition was
published in 1995, which was the same year as 100BASE-TX
was published
as a standard. While I agree that there is a lot of data to be
collected, I believe that a large volume of data has been
collected and
placed on the following web site:
http://www.ieee802.org/3/10GBT/public/material/
What I'd like to find out from you (Dan and Geoff) is if you believe
that all that more data needs to be gathered before the Study Group
moves to Task Force or can this be covered if the Study Group
creates an
objective to meet specific FCC compliance requirements?
Thanks,
Brad
-----Original Message-----
From: DOVE,DANIEL J (HP-Roseville,ex1) [mailto:dan.dove@hp.com]
Sent: Wednesday, August 13, 2003 2:02 PM
To: 'Geoff Thompson'
Cc: stds-802-3-10gbt@ieee.org
Subject: RE: [10GBASE-T] RE: EMI Discussion
Hi Geoff,
Good point of clarification.
I was not directly involved in that effort. At the time I was
working on
802.4 (rf modems,CATV,etc) but I know a number of the folks
who worked
on it
and actually have an original copy of the massive binder
full of work
done
by Bob Conte et al. It was an impressive effort and I think we are
looking
at something similar here.
Regards,
Dan
-----Original Message-----
From: Geoff Thompson [mailto:gthompso@nortelnetworks.com]
Sent: Wednesday, August 13, 2003 10:49 AM
To: DOVE,DANIEL J (HP-Roseville,ex1)
Cc: stds-802-3-10gbt@ieee.org
Subject: RE: [10GBASE-T] RE: EMI Discussion
Dan-
At 12:03 PM 8/13/2003 -0400, DOVE,DANIEL J
(HP-Roseville,ex1) wrote:
In the case of 10BASE-T, where we were
applying high speed (10MHz?) signals to CAT3 wiring which
had been installed
for phone support, a *huge* quantity of testing was done to
verify signal
integrity, EMI compatibility, and noise immunity.
Actually it was not CAT3, The installed base was AT&T DIW
(or worse).
We considered DIW as the baseline.
The TIA CAT3 spec was not approved until after the approval
of 10BASE-T.
Geoff
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