Re: [10GBT] Request for Cat6 Emissions Characteristics
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-----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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