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RE: [10GBASE-T] clarification on voltage level


Can you please refer to the exact source of the FCC limits presented in the
tutorial, namely 49dBuV/m up to roughly 80MHz, 54dBuV/m between
80MHz-216?MHz, 56dBuV/m above 216MHz. ( all numbers for Class A limit picked
by observation the tutorial slide 10 ).


Boris Fakterman

-----Original Message-----
From: George Zimmerman []
Sent: Tuesday, January 14, 2003 7:59 PM
To: Rao, Sailesh;
Subject: RE: [10GBASE-T] clarification on voltage level

Do you have EMI data that you're willing to share that suggests that
1000BASE-T is a good reference point for the maximum achievable.  Note
that we presented some EMI measurements in the tutorial for emissions
from cabling.

-----Original Message-----
From: Rao, Sailesh [] 
Sent: Tuesday, January 14, 2003 9:30 AM
Subject: RE: [10GBASE-T] clarification on voltage level

Let's compare 1000BASE-T with the proposed system:

                          1000BASE-T        Proposed 10GBASE-T
Symbol Rate:               125MHz               833MHz
Transmit Shaping Filter:   0.75+0.25D           None
Launch Voltage:            2.0Vpp               3.0Vpp

In comparison with 1000BASE-T, the proposed system is using the cable
beyond the specified frequency range, amplifying the launch voltage by
and then eliminating the spectral filter. 

Even if we assume that the DM-CM conversion of the cable behaves
over the unspecified frequency ranges of the cable, this doesn't look


-----Original Message-----
From: Vivek Telang [] 
Sent: Tuesday, January 14, 2003 9:59 AM
Subject: RE: [10GBASE-T] clarification on voltage level

This is true. Moreover, the emission levels can be meaningfully measured
only at the "system" level and not at the transceiver level. For
example, a
prototype of a switch or a NIC is used to make sure that the final
product meets the FCC requirements.

So it is extremely difficult (if not impossible) to answer the question
"does this line code meet FCC requirements". But what you can do, is
the transmitted spectra of two line codes, and *assuming all other
being equal*, make the claim that one line code will have XdB more
margin to
the FCC requirement, if its transmitted spectrum is XdB lower than that
the other line code.

Note that the shape of the transmitted spectrum, and the peak
power are as important (and IMHO more important) than the average
transmitted power.



Vivek Telang
Cicada Semiconductor
811 Barton Springs Road, Suite 550
Austin, TX 78704.
(512) 327-3500 x114

> -----Original Message-----
> From:
> []On Behalf Of John
> DeAndrea
> Sent: Monday, January 13, 2003 8:56 PM
> To:;
> Subject: RE: [10GBASE-T] clarification on voltage level
> We will need more information on cable balance and shielding to answer
> this question. It is not a simple calculation of pp voltage to FCC
> emission levels, but related to differential to common mode conversion
> in the cable and integrity of the grounding of the cable to the MDI.
> John DeAndrea
> iTerra Communications
> -----Original Message-----
> From: [] 
> Sent: Monday, January 13, 2003 6:16 PM
> To:
> Subject: Re: [10GBASE-T] clarification on voltage level
> Can anybody who is familiar with FCC requirement give a careful
> calculation on the highest possible voltage and launch power that meet
> the FCC regulation.
> Xiaopeng Chen
> Marvell Semiconductor Inc.