[SI-LIST] Re: How to Measure Ground Noise
- From: Zhangkun <zhang_kun@xxxxxxxxxx>
- To: doug@xxxxxxxxxx, Istvan.Novak@xxxxxxx
- Date: Fri, 08 Apr 2005 13:49:58 +0800
Doug
Do you have any paper on this topic?
Best Regards
Zhangkun
2005.4.8
----- Original Message -----
From: "Doug Smith" <doug@xxxxxxxxxx>
To: <Istvan.Novak@xxxxxxx>
Cc: <zhang_kun@xxxxxxxxxx>; <istvan.novak@xxxxxxx>; <ospyng@xxxxxxxxx>;
<si-list@xxxxxxxxxxxxx>
Sent: Friday, April 08, 2005 12:27 PM
Subject: Re: [SI-LIST] Re: How to Measure Ground Noise
> Hi Zhangkun, Istvan, and the group,
>
> I would like to modify Istvan's response somewhat.
>
> Ground currents flowing from the circuit, through the probe ground
> lead, and down the shield into the scope chassis typically (although
> not always) dominates everything else. It is just L(of the ground
> lead)di/di that creates a voltage across the probe from tip to ground
> lead attachment point to the probe. The probe reads this voltage like
> any other. This voltage is typically about 50 to 100 times larger than
> what leaks through the probe cable shield.
>
> Doug
>
> Istvan Novak wrote:
>
> > Dear Zhangkun,
> >
> > If you connect the signal and ground pins of a probe together and
> > connect both to a ground point on your system, the signal you see on the
> > oscilloscope could be a combination of several things: close-field
> > radiated noise picked up by the active probe head, radiated noise picked
> > up by the cable connecting the probe head to the scope, large
> > common-mode noise converted somewhere along the path due to saturation
> > of circuitry, etc., etc. The purpose of such baseline measurement is not
> > necessarily to identify the sources or these noise contributors one by
> > one, rather to establish their cumulative effect as a lower limit of the
> > measured values, below which you need to throw out the data.
> >
> > Best regards,
> > Istvan
>
> .......lots of lines deleted
>
>
> --
> -------------------------------------------------------
> ___ _ Doug Smith
> \ / ) P.O. Box 1457
> ========= Los Gatos, CA 95031-1457
> _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799
> / /\ \ ] / /\ \ Mobile: 408-858-4528
> | q-----( ) | o | Email: doug@xxxxxxxxxx
> \ _ / ] \ _ / Website: http://www.dsmith.org
> -------------------------------------------------------
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
