[SI-LIST] Re: Ethernet emissions.
- From: "Grasso, Charles" <Charles.Grasso@xxxxxxxxxxxx>
- To: "bryan@xxxxxxxxxxxxxx" <bryan@xxxxxxxxxxxxxx>, "leeritchey@xxxxxxxxxxxxx" <leeritchey@xxxxxxxxxxxxx>
- Date: Tue, 9 Apr 2013 16:44:33 +0000
Hello Bryan,
I strongly recommend that you contact SMSC and ask them for advise.
They are the experts in their phy (after all) and may have seen this issue
(if it is from their phy) before.
They will also recommend connector that you should use with their phy,
Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042974@xxxxxxxxx
(e) charles.grasso@xxxxxxxxxxxx
(e2) chasgrasso@xxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Bryan Ackerly
Sent: Sunday, April 07, 2013 8:16 PM
To: leeritchey@xxxxxxxxxxxxx
Cc: <HUBING@xxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
Subject: [SI-LIST] Re: Ethernet emissions.
Lee, I try to never cut up ground planes. This is the one "golden rule" i took
away from one your own training courses I attended many years ago....
Regards,
Bryan Ackerly
On 07/04/2013, at 4:19 AM, "Lee " <leeritchey@xxxxxxxxxxxxx> wrote:
> Todd,
>
> Thanks for reiterating the need to avoid cutting up ground planes. I
> am puzzled as to why anyone would recommend such a tactic. But, then,
> there are a host of such "off the cuff" things that get circulated
> year after year without any proof they are valid. Even more puzzling
> is why engineers accept such claims without supporting evidence that they are
> valid.
>
> They keep me very busy most of the time fixing problems that they cause!
>
> -----Original Message-----
> From: Todd Hubing
> Sent: Saturday, April 06, 2013 10:54 AM
> To: <si-list@xxxxxxxxxxxxx>
> Subject: [SI-LIST] Re: Ethernet emissions.
>
> Bryan,
>
>
> Please don't cut up your ground. I wouldn't want anyone on this list
> to get the idea that isolating grounds is going to solve a radiated
> emissions problem above 100 MHz. From the symptoms and the
> measurements you describe, it appears that you are driving the cable
> relative to your circuit board ground with a CM voltage produced
> directly by the PHY and insufficiently attenuated by the connector
> magnetics. If you've maintained balance in your layout between the PHY
> and the connector, you may need to consider using a different connector with
> better CM rejection.
>
>
>
> At these frequencies, nothing you do with your ground is going to
> improve upon the solid plane that you currently have. Trying to
> establish separate grounds that are at different potentials is likely to make
> things worse.
>
>
>
> Todd
>
> -----
>
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