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From: James Meyer
Subject: Re: Ground loops?
X-Newsreader: Forte Agent 1.91/32.564
Date: Sun, 15 Sep 2002 14:10:03 GMT
NNTP-Posting-Date: Sun, 15 Sep 2002 10:10:03 EDT
On Sun, 15 Sep 2002 01:23:46 GMT, "Brill Pappin" wrote:
>- Separate the power, digital and analog grounds into separate line (makes
>for larger cables, but doable I think).
The major dificulty here is ensure that each different ground wire
carries only the currents it's supposed to. That sounds easy until you try it.
>- Add filters to the power ground. (can they be added to the analog ground?,
>not to digital I would expect).
I don't think you can "filter" any ground lead.
>- Ensure that all analog and digital grounds on a particular device contain
>their own ground planes etc, and only feed to power ground once properly
>filtered (Is that even right? or should it be multiple points?).
Same problem(s) as the first two....
>- Use buffers/inverters between boards... mostly this would not be a problem
This one has some promise. Single-ended buffers won't buy you anything,
but differential buffer/drivers and receivers will work very well for both
digital and analog signals.
It's also possible to convert *all* the analog and digital signals into
and out of an individual board into digital signals and send them to everybody
with a multi-drop scheme like RS-485 or CAN BUS or even ethernet.
Add to that a higher Vcc supply on the "bus" and individual local Vcc
regulators on each board and you begin to get something with a proven track
record for not having noise or cross-talk problems.
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