We have found the limited resolution of EMCscan to limit (!) its usefulness -
it can't pinpoint IC level problems, for example. Although marketed for
emissions work, it is not usually the best tool if you are hunting down
radiated emissions, since its response to (large) differential-mode currents
will tend to swamp out its response to (small) common-mode currents. The
color plots are fun to look and occasionally can spark some intuition.
As Kyle said, the practical requirement of laying a PCB flat against it makes
it tough to use for much of our work.
Lee Hill
Silent Solutions LLC
EMC Consulting & Training
www.silent-solutions.com
In a message dated 8/8/2001 11:26:55 AM Eastern Daylight Time,
george.stu...@watchguard.com writes:
> From: george.stu...@watchguard.com (George Stults)
> Sender: owner-emc-p...@majordomo.ieee.org
> Reply-to: george.stu...@watchguard.com (George Stults)
> To: keh...@lsil.com ('Ehler, Kyle'), ken.ja...@emccompliance.com ('Ken
> Javor'), emc-p...@majordomo.ieee.org
>
>
>
>
> I also looked at EMSCAN about 2 years ago. I seem to recall that it was
> limited to a little over 1GHz on the top end at that time. We didn’t buy
> it, because we had harmonics above 1 GHz.
>
> -George
>
> -----Original Message-----
> From: Ehler, Kyle [mailto:keh...@lsil.com]
> Sent: Tuesday, August 07, 2001 12:24 PM
> To: 'Ken Javor'; emc-p...@majordomo.ieee.org
> Subject: RE: EMSCAN (was TV nostalgia/EMI sniffer goggle)
>
> I mini-evaluated an EMSCAN about 4 years ago. Cute tool!
> At the time, this little gem utilized a planar array of 1,024
> microantennae, coupled to an RF processor and pc.
> The radiation display is a user-variable-interpolation color map (spectral
> or spatial), but a bit imprecise in X-Y location, and forget about the Z
> plane. You could see a circuit trace acting as an emitter, but you have to
> be diligent in comparing the pwb layout with the schematic and the tool's
> radiation profile report. It was also a bit slow. That might have changed
> since then.
> Here's a link: <A
> HREF="http://www.emscan.com/product/prodline.html";>http://www.emscan.com/product/prodline.html</A>
>
> I could not sell our pcb design engineers on the tool -not even for use as
> a prescanner. Now our mechanical folks are having a dickens of a time
> containing 2Gbps fibre channel harmonics after the pcb design is done.
> Thanks for the job security. <boneheads>
> The biggest problem with this weapon was the absolute need for close
> proximity and repeatable indexing. This severely affects the accuracy and
> repeatability of the results, making before/after comparisons questionable..
> For many of us, placing an operating pwb on a planar surface for scanning
> presents a major challenge.
> I dont know about you, but we have a backplane that the pwb plugs into,
> then of course there is cabling, power supplies and cooling to worry about..
> Not to mention the CRU canisters for each module. Then it needs to be
> functional.
> I witnessed differences in emission profile that were highly sensitive to
> operating modes of the firmware loops and application software. It is
> extremely difficult if not impossible to do an accurate comparison of a
> bare board to an assembled and completely functioning EUT. So you are
> forced to scan a bare board rather than a fully configured and functioning
> system. For our purposes (debugging the EMI containment) this was of no
> practicality. Back to sniffer loops and horns..
> On the other hand, one of the proper ways to design for compliance is to
> design for containment of the emissions at the [board level] source. This
> is where the practicality of the EMSCAN comes into play. I found the
> tool's virtue for scanning the solder side of the board (close proximity)
> excellent, but for the component side (which is where most of the radiation
> sources and fixes would occur) the proximity was poor, grossly affecting
> the location and precision of the readings.
> btw I dont work for, or have any connection with, EMSCAN.
> kyle
> -----Original Message-----
> From: Ken Javor [<A
> HREF="mailto:ken.ja...@emccompliance.com";>mailto:ken..ja...@emccompliance.com</A>]
>
> Sent: Monday, August 06, 2001 5:58 PM
> To: John Woodgate; emc-p...@majordomo.ieee.org
> Subject: Re: TV nostalgia
>
> You could use an array of very short dipoles or small loops and gain in
> resolution by giving up efficiency, meaning that the viewer would have to be
>
> near the source. Although I have no detailed knowledge of it, I expect this
>
> is the principle behind the devices upon which you lay an operating PCB and
> the device maps hot spots. But clearly you will never get optical or IR
> viewer resolutions.
> ----------
> >From: John Woodgate <j...@jmwa.demon.co.uk>
> >To: emc-p...@majordomo.ieee.org
> >Subject: Re: TV nostalgia
> >Date: Mon, Aug 6, 2001, 12:28 PM
> >
> >
> > <95fbd8b0830ed511b7720002a51363f1319...@exw-ks.ks.lsil.com>, Ehler, Kyle
> > <keh...@lsil.com> inimitably wrote:
> >> Doug has touched on what I think would be a great tool for the
> >> EMI hunter...but rather than a 'sniffer', a 'goggle' similar
> >> to what Geordi wears that facilitates the direct viewing of EM
> radiation.
> >>
> >> Ideally, the device would allow adjustable band 'viewing' of the
> radiation
> >> frequency, intensity, polarity and propagation pattern(s).
> >
> > Yes, it sounds much more attractive than a sniffer, which would produce
> > BAD smells around some equipment. And it isn't technically unfeasible.
> > The problem is the poor resolution, even a microwave frequencies, due to
> > the wavelength of the emission. At 150 kHz, the wavelength is 2 km, so
> > only very BIG things are visible.
> > --
> > Regards, John Woodgate, OOO - Own Opinions Only. <A
> > HREF="http://www.jmwa.demon.co.uk/";>
> http://www.jmwa.demon.co.uk/</A>
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> To: "'Ehler, Kyle'" <keh...@lsil.com>,
> "'Ken Javor'"
> <ken.ja...@emccompliance.com>,
> emc-p...@majordomo.ieee.org
> Subject: RE: EMSCAN (was TV nostalgia/EMI sniffer goggle)
> Date: Wed, 8 Aug 2001 08:09:30 -0700
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