Ian,
A signal that strong suggests one possibility to me. It is possible
that the board layout was automatically routed. As a result a clock
trace was run through the Ethernet magnetics area. This area should
be clear of everything but the Ethernet signals. The application
notes for the Et
Ian,
the question you posted is so generic that nobody can really answer it. It
does not give any clue regarding the sources and mechanisms of emission, no
results of your troubleshooting, nor does it give any insight into the product
and possible causes of the increased emission. If you provid
-485-2537
fax: 858-485-3788
_
From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org] On Behalf Of
Ken Javor
Sent: Friday, June 17, 2005 5:30 AM
To: McBurney, Ian [Allen & Heath UK]; emc-p...@ieee.org
Subject: Re: ethernet radiated emissions
No experience with Ethernet pe
33MHz - sounds like PCI bus. The radiation originating from Ethernet is very
broadband per se as the data is scrambled using
a pseudo-random code, thus widening the spectrum. This was intended to reduce
EMI.
There are several things to think of:
- The traces between the magnetics and the connector
Ian,
PCB layout is very critical; especially in the I/O area (around the RJ-45
connectors). Make sure that the Ethernet transformer you use has good
common-mode filtering built in. You might also try using "Bob Smith
termination" on the un-used pins of the I/O connector. If you've never heard
of
No experience with Ethernet per se, so this is a very general comment. It
sounds as if the emissions are common mode. If so, they may not have anything
to do with the Ethernet itself, the Ethernet may be a fortuitous conductor. I
would check this using a current probe around the cable, with and
I read in !emc-pstc that neve...@attbi.com wrote (in <20021011040337.NIT
V4193.rwcrmhc51.attbi.com@rwcrwbc69>) about 'Ethernet Radiated
Emissions' on Fri, 11 Oct 2002:
>Second, I recommend refraining from sarcastic comments
>in this forum, since that doesn't seem it was about
>naivety.
No sar
> Pardon my naivety, but how does '100 Mbit' relate to
frequencies of 30 and 60 kHz? Is this 100 Mbit per week?
(;-)
> --
> Regards, John Woodgate, OOO - Own Opinions Only.
http://www.jmwa.demon.co.uk
First, a little background on auto negotiation. The IEEE
802.3u 100BaseTX auto negotiatio
[ Neven wrote ]
> You are seing a spectrum of MLT3 signal, which is 100
> Mbit coding.
[ John wrote ]
> Pardon my naivety, but how does '100 Mbit' relate to frequencies
> of 30 and 60 kHz? Is this 100 Mbit per week? (;-)
Could be plenty. I'd guess is something to do with either jitter and
I read in !emc-pstc that neve...@attbi.com wrote (in <20021010021029.WVI
M20316.sccrmhc03.attbi.com@rwcrwbc56>) about 'Ethernet Radiated
Emissions' on Thu, 10 Oct 2002:
>You are seing a spectrum of MLT3 signal, which is 100
>Mbit coding.
Pardon my naivety, but how does '100 Mbit' relate to freq
STP on the offsite portion of the cable will be an interesting test.
>
> Thanks for the input.
>
> Rick Linford
>
>
>
>
> -Original Message-----
> From: Andy White (EWU) [mailto:andy.wh...@ewu.ericsson.se]
> Sent: Wednesday, October 09, 2002 3:39 PM
> To: Rick L
I read in !emc-pstc that rlinf...@sonicwall.com wrote (in ) about 'Ethernet
Radiated Emissions' on Wed, 9 Oct 2002:
> With all cables attached and not linked there is no broadband. Reducing the
>resolution shows peaks every 60 kHz. Probing on a linked signal shows peaks
>every 30 kHz with ever
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