RE: [SI-LIST] : Measuring Ground Noise

Larry Smith ([email protected])
Wed, 24 Jun 1998 08:51:28 -0700 (PDT)

> > Agreed on all points. What follows, however, is that you can measure
> > localized noise on your ground plane - you just need to figure out
> what
> > your reference point will be.
> But, to measure noise _across_ your ground plane, requires attaching
> probe wires some distance apart ... which requires wires of some length.
> How to do that effectively and believe the results? (And in the first
> place, what is the significance of noise across the ground plane?)
> Regards,
> Andy Ingraham

And, in our business, distance and time are the same thing. To measure
a voltage across a distance is the same as measuring voltage at two
different times. How do you interpret a voltage measurment that is
made across time?? Local measurements with probe lengths that are
much, much less than one wavelength are the only ones that make sense.

Larry Smith
Sun Microsystems

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