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Comments from Sterling Vaden:|
DOVE,DANIEL J (HP-Roseville,ex1) wrote:
I agree that that is a good objectiveHi 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.
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.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.
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.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.
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.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.
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 Forcerelative to EMI compliance. Do you agree with that approach? Thanks, Brad -----Original Message----- From: DOVE,DANIEL J (HP-Roseville,ex1) [mailto:firstname.lastname@example.org] Sent: Wednesday, August 13, 2003 6:22 PM To: Booth, Bradley; email@example.com 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:firstname.lastname@example.org] Sent: Wednesday, August 13, 2003 1:24 PM To: email@example.com 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-TXwas publishedas 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:firstname.lastname@example.org] Sent: Wednesday, August 13, 2003 2:02 PM To: 'Geoff Thompson' Cc: email@example.com 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 folkswho workedon it and actually have an original copy of the massive binderfull of workdone 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:firstname.lastname@example.org] Sent: Wednesday, August 13, 2003 10:49 AM To: DOVE,DANIEL J (HP-Roseville,ex1) Cc: email@example.com 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 whichhad been installedfor phone support, a *huge* quantity of testing was done toverify signalintegrity, 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