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[10GBT] FW: Cat6 Emissions Characteristics.....



Hi All,

I'm not qualified to determine the PSD of PAM8, nor PAM12.  I can offer some
experience relative to the objective under discussion.

I've built a rather larger number of 100Base-TX, 1000BaseT systems, and one
very
successful 10GE system.

It's been my experience that as a systems designer, I generally don't have
trouble
"containing" the EMI produced by the clock drivers and oscillators
associated
with the PHYs.

I've had no end of trouble containing the EMI "out the wire" (i.e. the
transmit
PSD).

Hope this helps close the coding issue sooner.

KR

-----Original Message-----
From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On Behalf
Of sailesh rao
Sent: Thursday, July 22, 2004 5:45 PM
To: STDS-802-3-10GBT@listserv.ieee.org
Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics


Sanjay,

Please don't preach to me about objectivity.

I stand by the statements I've made. I consider the point Jose made about
the emissions issue to be pure specmanship, and I've already stated that it
is completely irrelevant. I know and I hope you know that systems vendors
will have more issues with the emissions from any weird clock sources we
implement (N/M PLLs for the PAM12 825Mhz symbol rate, for instance) than
from the transmit PSD itself.

Regards,
Sailesh Rao.
srao@phyten.com

>From: Sanjay Kasturia <SKasturia@TERANETICS.COM>
>Reply-To: "IEEE P802.3an" <STDS-802-3-10GBT@listserv.ieee.org>
>To: STDS-802-3-10GBT@listserv.ieee.org
>Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
>Date: Thu, 22 Jul 2004 16:07:12 -0700
>
>Sailesh,
>
>You have justified the 20Log10 "EMI" factor multiple times in the past.
>
>You initially claimed that 8PAM was better than 12PAM on EMI even with
>this 20log10 EMI factor.
>
>When Jose pointed out errors in your code and after correction 8PAM
>looked worse than 12PAM you are suggesting dropping the 20Log10 EMI
>factor.
>
>This makes me doubt the objectivity of your analysis.
>
>Regards,
>
>
>Sanjay
>
>sanjay@teranetics.com
>cell (650) 704-7686
>office (408) 653-2235
>
>-----Original Message-----
>From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
>Behalf Of sailesh rao
>Sent: Thursday, July 22, 2004 3:09 PM
>To: STDS-802-3-10GBT@LISTSERV.IEEE.ORG
>Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
>
>Hi All,
>
>Here is the fixed matlab code and the fixed PDF file. The earlier code
>was missing a sqrt(fs) normalization to account for the fact that only a
>single pulse was being used for the PSD computation. I've also deleted
>the 20log10 "EMI PSD" computation, for the reasons I outlined earlier.
>
>Sorry for the confusion.
>
>Regards,
>Sailesh Rao.
>srao@phyten.com
>
> >From: "Booth, Bradley" <bradley.booth@INTEL.COM>
> >Reply-To: "IEEE P802.3an" <STDS-802-3-10GBT@listserv.ieee.org>
> >To: STDS-802-3-10GBT@listserv.ieee.org
> >Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
> >Date: Thu, 22 Jul 2004 12:44:36 -0700
> >
> >Sailesh,
> >
> >Thanks for the concern about the Task Force Chair, but I'm not too
> >concerned about the Working Group suddenly turning into a bunch of
> >cannibals. :-)  If there is going to be an emissions issue, let's get
> >it out in the open now (no pun intended).
> >
> >Thanks,
> >Brad
> >
> >-----Original Message-----
> >From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
> >Behalf Of sailesh rao
> >Sent: Thursday, July 22, 2004 8:54 AM
> >To: STDS-802-3-10GBT@listserv.ieee.org
> >Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
> >
> >
> >Jose,
> >
> >You appear to have a valid point. I'll check the scaling used in these
> >matlab functions and get back to you.
> >
> >However, for the sake of this task force chair, I hope you are wrong.
> >If I have to lower the 1000BASE-T PSD by ~10dB, I'm afraid that some
> >members of our working group will eat Brad Booth alive on the 10GBASE-T
>
> >emissions issue.
> >
> >Meanwhile, I renew my request to Scott Powell to please publish a file
> >version of the emissions characteristics he used to compute the
> >contents of slide 6 of powell_1_0704.pdf.
> >
> >Regards,
> >Sailesh Rao.
> >srao@phyten.com
> >
> >----- Original Message -----
> >From: "Jose Tellado" <JTellado@TERANETICS.COM>
> >To: <STDS-802-3-10GBT@listserv.ieee.org>
> >Sent: Wednesday, July 21, 2004 7:10 PM
> >Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
> >
> >
> > >Sailesh,
> > >
> > >There must be something wrong with the code, when the integral of the
>
> > >1GBaseT PSD power is 15dBm (details below).
> > >
> > >I thought I gave you a good hint, and I rather you debug your code.
> > >
> > >The problem is likely in your modeling of the digital/analog sampling
>
> > >rate conversion, lines 12-35.
> > >You can check the 3rd chapter of (or any other introductory DSP
>book):
> > >Oppenheim and Shafer, "Discrete Time Signal Processing". It's eq
> > >(3.49) in my undergrad international edition.
> > >
> > >Jose
> > >
> > >
> > >1GBase-T power details:
> > >
> > >10*log10(sum(10.^((f5mag-116)/10)))+60 = 15.3dBm
> > >
> > >This equation computes the (discrete) integral of the PSD, where
> > >(f5mag-116) is the PSD from your code, and 60dB converts from MHz to
> >Hz.
> > >
> > >
> > >
> > >-----Original Message-----
> > >From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG] On
>
> > >Behalf Of sailesh rao
> > >Sent: Wednesday, July 21, 2004 3:29 PM
> > >To: STDS-802-3-10GBT@listserv.ieee.org
> > >Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
> > >
> > >Jose,
> > >
> > >Please point out which lines in the matlab code I distributed,
> > >spectra.m, have "bugs".
> > >
> > >Regards,
> > >Sailesh Rao.
> > >srao@phyten.com
> > >
> > > >From: Jose Tellado <JTellado@TERANETICS.COM>
> > > >Reply-To: "IEEE P802.3an" <STDS-802-3-10GBT@listserv.ieee.org>
> > > >To: STDS-802-3-10GBT@listserv.ieee.org
> > > >Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
> > > >Date: Wed, 21 Jul 2004 12:14:42 -0700
> > > >
> > > >Sailesh,
> > > >
> > > >It appears you have a bug in your program. You are assuming that
> >PAM12
> > > >is transmitting 0.8dB more power than PAM8 which is unfair. When
> > > >you correct for this PAM12 should have better EMI.
> > > >
> > > >Jose
> > > >
> > > >Details:
> > > >
> > > >When I compute the total power transmitted for the PAM8 case by
> > > >integrating the PSD I get 4.1dBm
> > > >
> > > >10*log10(sum(10.^((f8mag-116)/10)))+60 = 4.1dBm
> > > >
> > > >But when I compute the total power tx for the PAM12 case I get
> > > >4.9dBm
> > > >
> > > >10*log10(sum(10.^((f12mag-116)/10)))+60 = 4.9dBm
> > > >
> > > >
> > > >PS. You probably made a mistake in the Butterworth filtering
> > > >sampling rate adjustment or in a amplitude/power log mix-up.
> > > >
> > > >
> > > >-----Original Message-----
> > > >From: stds-802-3-10gbt@IEEE.ORG [mailto:stds-802-3-10gbt@IEEE.ORG]
> > > >On Behalf Of sailesh rao
> > > >Sent: Wednesday, July 21, 2004 9:37 AM
> > > >To: STDS-802-3-10GBT@LISTSERV.IEEE.ORG
> > > >Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
> > > >
> > > >Jose,
> > > >
> > > >It turns out that when you take into account the analog filtering
> > > >and do an accurate calculation of the PSD/"EMI PSD", neither PAM8
> > > >nor
> >PAM12
> > >
> > > >has an advantage in terms of EMI. I'm attaching the PDF ouput and
> > > >the matlab code to generate the PSDs using both Ungerboeck's analog
> >filter
> > > >construction (3rd order BW LPF at fs/4) and using the (0.75+0.25D)
> > > >approach used in our July presentation (with 5th order BW LPF at
> >fs/2).
> > > >In both cases, the peaks for the so-called "EMI PSD"s are within
> >0.01dB
> > >
> > > >of each other for PAM8 and PAM12.
> > > >
> > > >Regards,
> > > >Sailesh Rao.
> > > >srao@phyten.com
> > > >
> > > > >From: Jose Tellado <JTellado@TERANETICS.COM>
> > > > >Reply-To: "IEEE P802.3an" <STDS-802-3-10GBT@listserv.ieee.org>
> > > > >To: STDS-802-3-10GBT@listserv.ieee.org
> > > > >Subject: Re: [10GBT] Request for Cat6 Emissions Characteristics
> > > > >Date: Wed, 21 Jul 2004 00:06:30 -0700
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >All,
> > > > >
> > > > >From talking to several 10GBase-T EMI experts, the general
> >consensus
> > > > >is
> > > >
> > > > >that EMI emissions increase with frequency as 20*log10(f).
> > > > >
> > > > >Thus the system with the higher symbol rate (PAM8 at 1000MHz)
> > > > >will have
> > > >
> > > > >worse EMI if the tx power is the same and both have equivalent
> > > > >digital and analog filtering.
> > > > >
> > > > >The plot below shows the EMI PSD for 1GBase-T, PAM12 and PAM8
> > > > >assuming all have the same digital filter 3/4+1/4D. As expected
> > > > >the
> > > > >PAM8 is the worse, since it has the most signal at higher
> > >frequencies.
> > > > >
> > > > >
> > > > >
> > > > >I only plotted the PSD up to 0.4*SymbolRate, because the analog
> > > > >filters
> > > >
> > > > >will typically have >3dB attenuation at 0.5*Symbol rate and the
> > > > >PSD is mostly dependent on the analog filters. PAM12 and PAM8
> > > > >will both have similar analog filters.
> > > > >
> > > > >For those interested in the details I included the matlab code.
> > > > >For
> >a
> > >
> > > > >fixed tx power the PSD level (dBm/Hz) will drop as -10*log10(BW)
> >when
> > >
> > > > >we increase the bandwidth, BW. But as we increase the BW, the EMI
>
> > > > >increases as 20*log10(BW). Clearly the increase in EMI in PAM8 is
>
> > > > >twice
> > > >
> > > > >as bad as the PSD level drop.
> > > > >
> > > > >Thus PAM12 has 10*log10(1000)=0.8dB more signal at low
> > > > >frequencies, but
> > > > >PAM8 has 1.6dB more EMI at high frequencies. Therefore PAM8 has
> >0.8dB
> > >
> > > > >more EMI
> > > > >
> > > > >Jose
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >-----Original Message-----
> > > > >From: stds-802-3-10gbt@IEEE.ORG [
> ><mailto:stds-802-3-10gbt@IEEE.ORG>
> > > > >mailto:stds-802-3-10gbt@IEEE.ORG] On Behalf Of sailesh rao
> > > > >Sent: Tuesday, July 20, 2004 6:55 PM
> > > > >To: STDS-802-3-10GBT@listserv.ieee.org
> > > > >Subject: [10GBT] Request for Cat6 Emissions Characteristics
> > > > >
> > > > >Hi All,
> > > > >
> > > > >At the request of a task force member, I computed the transmit
> > > > >PSD for PAM8,
> > > > >PAM12 and 1000BASE-T, and discovered that I added the
> > > > >contribution
> >of
> > >
> > > > >Jose's 0.4dB incorrectly in my Total EMI Penalty calculations in
> >the
> > > > >updated table.
> > > > >Actually, in the passband, the transmit PSD for PAM8 after THP is
>
> > > > >1.6dB
> > > >
> > > > >lower than the transmit PSD for PAM12 after THP, and not 0.8dB
> >lower
> > > > >as
> > > >
> > > > >I had reported earlier.
> > > > >
> > > > >However, rather than simply adding another 0.8dB to the PAM12 EMI
>
> > > > >penalty, I would like to propose that we compute the estimated
> > > > >emissions characteristics of the PAM8/PAM12 transmit PSDs, for
> > > > >different transmit filtering choices, over typical Cat6 cabling
> > > > >and assess the difference in peaks to estimate the true emissions
> >penalty
> > >
> > > > >for one PAM approach over the other. I know Scott Powell had
> > > > >published a PDF version of measured 4-connector Cat6 emissions
> > > > >characteristics for a flat transmit PSD (powell_1_0303.pdf), but
> > > > >do cabling experts agree with Scott's measurements and can the
> > > > >task force use that data to
> > > >
> > > > >assess the emissions characteristics of PAM8 vs. PAM12? If so, I
> > > > >would like to request Scott to publish a file version of his
> > > > >measurements on the task force web site so that we can all use it
> >to
> > > > >do fair comparisons. If not, are there other typical Cat6 cabling
>
> > > > >emissions measurements that we can use to do the emissions
> > >comparisons?
> > > > >
> > > > >Any input from the cabling experts on the reflector would be
> >greatly
> > > > >appreciated.
> > > > >
> > > > >Regards,
> > > > >Sailesh Rao.
> > > > >srao@phyten.com
> > > > >
> > > > >_________________________________________________________________
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> > > > >
> > > > >
> > > > ><< PSDPAM12andPAM8.m >>
> > > >
> > > >_________________________________________________________________
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