Re: [PSES] Conducted emissions for Split-phase 120/240V needs three-phase LISN?

[Brent DeWitt]

It may be worth noting at any LISN using magnetic cores/elements in the 
50uH bit, must be calibrated at the maximum rated current to verify that 
saturation isn't a problem.


On 4/5/2024 9:56 PM, Brent DeWitt wrote:
In my opinion, all of this is rather simple.  Any LISN, ANSI or CISPR, 
references the noise to "ground".  Any conductor not being measured 
should be terminated in 50 ohms.  Whatever network used needs to make 
that so.  Take your pick.


On 4/5/2024 9:43 PM, T.Sato wrote:

On Fri, 5 Apr 2024 22:01:29 GMT,
   Brian Gregory  wrote:

  Hello and Happy Friday, I've got a sales guy telling me our 
120/240V EUT needs two pair of single-phase LISNs for our CE test 
bench.That's only slightly cheaper than a 3-phase unit at > 50A, but 
very bulky. Can someone remind me why I'd need 4, 50A single-phase 
LISNs for our unit?  I could see 3 (one for the neutral) but I'm not 
so savvy on EMC test equipment.
I think you can use either single 3-phase (usually 4 conductors + PE) 
LISN
or two single-phase (2 conductors + PE) LISNs whichever you like, 
although

I would prefer to use a single 3-phase LISN.

BTW, there maybe confusion with the term "single-phase LISNs" here.
Is it LISNs commonly used for single-phase AC supply?
Or is it LISNs for an single power supplying conductor?

Regards,
Tom

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Re: [PSES] Conducted emissions for Split-phase 120/240V needs three-phase LISN?

[Brent DeWitt]

In my opinion, all of this is rather simple.  Any LISN, ANSI or CISPR, 
references the noise to "ground".  Any conductor not being measured 
should be terminated in 50 ohms.  Whatever network used needs to make 
that so.  Take your pick.


On 4/5/2024 9:43 PM, T.Sato wrote:

On Fri, 5 Apr 2024 22:01:29 GMT,
   Brian Gregory  wrote:


  Hello and Happy Friday, I've got a sales guy telling me our 120/240V EUT needs 
two pair of single-phase LISNs for our CE test bench.That's only slightly cheaper 
than a 3-phase unit at > 50A, but very bulky. Can someone remind me why I'd 
need 4, 50A single-phase LISNs for our unit?  I could see 3 (one for the neutral) 
but I'm not so savvy on EMC test equipment.

I think you can use either single 3-phase (usually 4 conductors + PE) LISN
or two single-phase (2 conductors + PE) LISNs whichever you like, although
I would prefer to use a single 3-phase LISN.

BTW, there maybe confusion with the term "single-phase LISNs" here.
Is it LISNs commonly used for single-phase AC supply?
Or is it LISNs for an single power supplying conductor?

Regards,
Tom

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Re: [PSES] Radiated Emissions - How many points to QP?

[Brent DeWitt]

This gets a bit more complicated for FCC regulations on emissions above 
1 GHz, where the prescribed detector is an average detector (at 1 MHz 
RBW) and the peak limit is defined as 20 dB above that.


On 4/5/2024 7:19 PM, Brent DeWitt wrote:
That is what I expected you meant, but a bit confusing based on the 
original topic.  You are certainly correct with respect to conducted 
emissions!


On 4/5/2024 7:14 PM, rmm.priv...@gmail.com wrote:


I was thinking conducted emissions in the context of average detectors.

*From:*Brent DeWitt 
*Sent:* Friday, April 5, 2024 3:48 PM
*To:* rmm.priv...@gmail.com; EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] Radiated Emissions - How many points to QP?

Could you clarify when you would choose to use an average detector 
for radiated emissions between 30 and 1000 MHz?


On 4/5/2024 6:39 PM, Ralph McDiarmid wrote:

I’m having trouble with /“Of those disturbances above (L-20dB),
where L is the limit level in logarithmic units, the disturbance
levels and the frequencies of at least the six highest
disturbances shall be recorded.”/

//

Does this CISPR measurement methods standard expect you to record
the six highest signals which are less than or equal to -20dB wrt
the *average limit* when using an*average detector *and the*QP
limit *when using a*QP detector*? Perhaps that is made clear in
the product-specific standard (like EN55022 or CISPR 11, etc)

Comments?

//

/Ralph/

*From:*Stultz, Mark
<0f79f2e10e47-dmarc-requ...@listserv.ieee.org>
<mailto:0f79f2e10e47-dmarc-requ...@listserv.ieee.org>
*Sent:* Friday, April 5, 2024 12:33 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* [PSES] Radiated Emissions - How many points to QP?

Hello PSES brain trust,

When doing radiated emissions measurements, how many frequencies
should be quasi-peaked?

CISPR 16-2-3 clause 6.4.9 states:

/“Of those disturbances above (L-20dB), where L is the limit
level in logarithmic units, the disturbance levels and the
frequencies of at least the six highest disturbances shall be
recorded.”/

We have always done QP measurements on all peak measurements
above the limit, even if that is more than six points.

I have a lab arguing that they only need to measure the top six,
regardless of how many peak measurements are above the limit.

Any thoughts are appreciated.

Thanks,

Mark



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Re: [PSES] Radiated Emissions - How many points to QP?

[Brent DeWitt]

That is what I expected you meant, but a bit confusing based on the 
original topic.  You are certainly correct with respect to conducted 
emissions!


On 4/5/2024 7:14 PM, rmm.priv...@gmail.com wrote:


I was thinking conducted emissions in the context of average detectors.

*From:*Brent DeWitt 
*Sent:* Friday, April 5, 2024 3:48 PM
*To:* rmm.priv...@gmail.com; EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] Radiated Emissions - How many points to QP?

Could you clarify when you would choose to use an average detector for 
radiated emissions between 30 and 1000 MHz?


On 4/5/2024 6:39 PM, Ralph McDiarmid wrote:

I’m having trouble with /“Of those disturbances above (L-20dB),
where L is the limit level in logarithmic units, the disturbance
levels and the frequencies of at least the six highest
disturbances shall be recorded.”/

//

Does this CISPR measurement methods standard expect you to record
the six highest signals which are less than or equal to -20dB wrt
the *average limit* when using an*average detector *and the*QP
limit *when using a*QP detector*? Perhaps that is made clear in
the product-specific standard (like EN55022 or CISPR 11, etc)

Comments?

//

/Ralph/

*From:*Stultz, Mark
<0f79f2e10e47-dmarc-requ...@listserv.ieee.org>
<mailto:0f79f2e10e47-dmarc-requ...@listserv.ieee.org>
*Sent:* Friday, April 5, 2024 12:33 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* [PSES] Radiated Emissions - How many points to QP?

Hello PSES brain trust,

When doing radiated emissions measurements, how many frequencies
should be quasi-peaked?

CISPR 16-2-3 clause 6.4.9 states:

/“Of those disturbances above (L-20dB), where L is the limit level
in logarithmic units, the disturbance levels and the frequencies
of at least the six highest disturbances shall be recorded.”/

We have always done QP measurements on all peak measurements above
the limit, even if that is more than six points.

I have a lab arguing that they only need to measure the top six,
regardless of how many peak measurements are above the limit.

Any thoughts are appreciated.

Thanks,

Mark



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Websi

Re: [PSES] I would like to hear your thoughts please

[Brent DeWitt]

Tough one!  The problem lies in the determination of "worst case". While 
it would be easy to presume that having all of the hardware populated is 
worst case, it overlooks the effects of un-terminated stubs and other SI 
related issues.  In addition, with the world of firmware based PLL 
clocks and memory traffic, it is a tough thing to determine.  My opinion 
would be to preform the simplest pre-scan on each configuration and base 
the final, rigorous certification based on that knowledge.


Brent Dewitt
Milford, MA

On 4/5/2024 6:47 PM, Lfresearch wrote:

Hi folks,

I would like to advise a client at where to draw the line on what needs 
testing. I would like to solicit opinions besides my own. Otherwise it’s the 
fox urging the chicken coop…

So a manufacturer that makes a product of which there will be several variants. 
All use the same board, but have different sections of circuits populated. This 
may require slightly different code to run on the same uP in each case.

So.. The burning question is can we perform and analysis that postulates a 
worse case hardware/software combination and test just one configuration? Or, 
do we have to do every combination?

Or, are there some guidelines about where we draw the line of what to test and 
what can be claimed as similarity?

Off list responses are welcome too.

Thanks,

Derek Walton
LFResearch/SSCLabs.

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Re: [PSES] Radiated Emissions - How many points to QP?

[Brent DeWitt]

Could you clarify when you would choose to use an average detector for 
radiated emissions between 30 and 1000 MHz?


On 4/5/2024 6:39 PM, Ralph McDiarmid wrote:


I’m having trouble with /“Of those disturbances above (L-20dB), where 
L is the limit level in logarithmic units, the disturbance levels and 
the frequencies of at least the six highest disturbances shall be 
recorded.”/


//

Does this CISPR measurement methods standard expect you to record the 
six highest signals which are less than or equal to -20dB wrt the 
*average limit* when using an*average detector *and the*QP limit *when 
using a*QP detector*? Perhaps that is made clear in the 
product-specific standard (like EN55022 or CISPR 11, etc)


Comments?

//

/Ralph/

*From:*Stultz, Mark <0f79f2e10e47-dmarc-requ...@listserv.ieee.org>
*Sent:* Friday, April 5, 2024 12:33 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* [PSES] Radiated Emissions - How many points to QP?

Hello PSES brain trust,

When doing radiated emissions measurements, how many frequencies 
should be quasi-peaked?


CISPR 16-2-3 clause 6.4.9 states:

/“Of those disturbances above (L-20dB), where L is the limit level in 
logarithmic units, the disturbance levels and the frequencies of at 
least the six highest disturbances shall be recorded.”/


We have always done QP measurements on all peak measurements above the 
limit, even if that is more than six points.


I have a lab arguing that they only need to measure the top six, 
regardless of how many peak measurements are above the limit.


Any thoughts are appreciated.

Thanks,

Mark



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Re: [PSES] ESD testing - Contact Mode to plated metal surfaces?

[Brent DeWitt]

I believe the language said something like: "the contact discharge tip 
shall be applied to any coating not expressly declared as insulative"


Could be wrong though.

Brent DeWitt
Milford, MA

On 9/18/2023 7:39 PM, Ken Wyatt wrote:
Always had the impression the sharp end of the CD tip was designed to 
punch through any coated metal.


Kenneth Wyatt
Woodland Park, CO
Sent from my iPhone.


On Sep 18, 2023, at 09:48, Sykes, Bob  wrote:



Worldly Experts,

I have a question regarding the suitability of contact mode ESD 
testing to plated metal surfaces.  I understand the wording in IEC 
61000-4-2 regarding painted and bare metal.  Does the same logic used 
for painted metal surfaces also apply to other coatings (anodized, 
plated, passivated etc.)?  These are not addressed in the Standard.


adTHANKSvance,

Bob Sykes



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Re: [PSES] thoughts on ESD test lab problems

[Brent DeWitt]

I suspect that folks who have been directly involved with air-discharge 
ESD can appreciate it's inherent, operator influenced, uncertainly.


Having run both internal and third party EMC test labs, I recognize that 
few things are done "perfectly" (whatever "perfect" is), but I've always 
considered it my responsibility to catch the errors and correct them 
before they influence my customers outcome.


The larger the lab, the more likely it is that the experience of the 
tester will vary.  I am not saying that the customer show bear the brunt 
of that, the lab should have test review processes in place to mitigate it.


Had to pitch in.

Brent DeWitt

On 8/12/2023 1:47 PM, John Mcbain wrote:

The basic question is, "How good is good enough?"
Risk standards for product safety address that question to some 
extent, but it applies to every lab measurement, whether the 
applicable standards (or regulations) consider it or not.


Best regards,
John McBain


On Sat, Aug 12, 2023 at 2:26 AM John Woodgate  wrote:

But crossing t's and dotting i's is exactly what is required by
competence standards, including the several ISO 170XX series.
Furthermore, standards specify performance of test equipment, if
possible, and only if that is not possible, they specify design.
If that is not possible, they specify construction, and indeed
many CISPR and other standards specify test set-ups with elaborate
drawings.

EMC testing is DIFFICULT. It does involve extensive experience and
it is costly. Management systems are/should be in place to catch
errors. Daily and weekly verifications are required. In many
cases, running tests on a known sample are OK, but that's dodgy
for ESD, because repeated testing WILL cause damage.

On 2023-08-12 03:25, Ken Javor wrote:


No way am I jumping in the middle of this debate, but it is
extremely useful in another way.

A few observations:

ESD is by its very nature a chaotic event (air discharge more so
than contact).

It is not entirely surprising that someone who has spent decades
working on something would find examples of non-idealities in the
work of technicians doing rote work following canned test
procedures.  A test facility isn’t going to make a profit
employing a septuagenarian devoted to crossing every “t” and
dotting every “i.”  (Written by someone pushing that age bracket
pretty hard).

IFF (if and only if) Mr. Smith’s observations are correct, that
is an indictment of the test requirement/method. That is, it is
the responsibility of the standards committees to write these
such that they can be adequately performed by the average test
facility and personnel. If it takes someone with five decades of
experience, and they must spend an inordinate amount of time
($$$) to get it right, then the standard is a failure.

-- 


Ken Javor

(256) 650-5261

*From: *"doug emcesd.com <http://emcesd.com>" 
<mailto:d...@emcesd.com>
*Reply-To: *"doug emcesd.com <http://emcesd.com>"
 <mailto:d...@emcesd.com>
*Date: *Friday, August 11, 2023 at 11:26 AM
*To: *
<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
*Subject: *Re: [PSES] thoughts on ESD test lab problems

I didn’t say most labs are bad. Errors do happen and for me
almost every lab I have used has made a mistake. These errors are
rare but do happen and the effect of a single error can be very
costly.

One lab made an especially bad mistake for a small company that
engaged me that cost the company a lot of money, has since
improved their game by instituting quality procedures they should
have had anyway. The lab gave the company passing data but in
fact the plot looked like the technician forgot to plug the
antenna in, noise level of the instrumentation!

Based on that, the company signed a contract for price and
delivery for a million units of their  product. The ultimate fix
needed was a different core design of an inductor that cost them
US $0.30. $300k is a lot of money for a small company.

I can give many more examples. Usually the problem causes a
product to fail when it actually should have passed. I have many
examples that happened to me over the last 40 years in both
private and commercial labs.

The errors are still rare, but do happen. Over enough testing a
person, like myself, will encounter an error with any given lab.

Of the errors I have encountered, three were the result of the
staff in the lab not being competent (over a span of 40 years),
the rest were just simple mistakes, maybe another dozen or so.
Again, this was over decades, so rare, but many millions of
dollars were at stake in each case.

In two cases, the lab personnel became a bit belligerent when I
gently sug

Re: [PSES] Simulation of signal source under a pwb shield

[Brent DeWitt]

Hi Chaz,

My thought is that concern over the simulated antenna can be neglected 
if the the source is "electrically short dipole" at the frequency of 
interest.  Simulating with the radiated field from such a source, with 
and without the shield, at a far field distance, should give you a 
decent approximation of the shield effectiveness.


Take care my friend!

Brent DeWitt, AB1LF
Milford, MA

On 7/21/2023 3:38 PM, Chas Grasso wrote:

Hello experts and gurus!!

I need to simulate the performance of a BLS (board level shield) and I 
am considering
using the IEEE Std 2716-2022 IEEE Guide for the Characterization of 
the Effectiveness of Printed Circuit Board Level Shielding document. 
This document is however an adaptation of
the methods of evaluating gaskets rather than a focused guide on BLS 
performance.


Question: Does anyone have experience using this Guide as intended for 
a BLS solution evaluation?


Another Question: Would someone guide me to a paper or experiment that 
shows
a decent correlation of a simulated source in a BLS versus actual 
measurements ?


Here's my concern: The problem of how to internally  source a signal 
for simulation and
measurement seems deceptively simple. Just put an antenna on the 
inside of the
shield - right? Well, no. My concern is that the addition of the 
shield compromises
the antenna characteristics and so inadvertently this results in 
better (or worse) results.


With eager anticipation and appreciation for your help with this!!
--

Charles Grasso

Dish Technologies

 (c) 303-204-2974

(w) 303-706-5467

(h) 303-317-5530

(e ) charles.gra...@dish.com

(e2) chasgra...@gmail.com



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Re: [PSES] Immunity test field strength, residential setting

[Brent DeWitt]

Like John, I have no idea why a "medical electrical device" standard has 
gotten tangled up with EV chargers.  I was one of the authors of the 2nd 
edition of the IEC standard, and the only devices under that standard 
that weren't patient connected were systems that connected those devices 
to outside data recording.  Nothing herre seems to apply!


- Brent DeWitt
My opinions have nothing to do with my current employer!

On 7/21/2023 5:10 PM, John Woodgate wrote:


Well, obviously 60601-1-2 doesn't apply, unless some clown claims that 
EV chargers are medical devices. The higher limits in 60601-1-2 for 
home healthcare are probably due to the expected absence of immediate 
intervention when a medical device misbehaves.


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. 
Xunzi (340 - 245 BC)



On 2023-07-21 20:30, Scott Aldous wrote:

Hi Brian,

The UL standard actually references IEC 61000-4-3 only for the test 
method. Per the UL standard, the test level, 20 V/m, comes from EN 
60601-1-2, which is the CENELEC EMC standard for medical devices.


Per this article 
<https://www.linkedin.com/pulse/understanding-central-differences-between-3rd-4th-edition-saeed>, 
at least the base standard, IEC 60601-1-2, references broad spectrum 
testing at 3 V/m for professional healthcare facility environment and 
10 V/m for home healthcare environment. Test levels from 9 to 28 V/m 
at specific frequencies are referenced to simulate proximity to 
fields due to wireless communications. IMO, the UL standard doesn't 
make clear if the actual test levels (and frequencies) from EN 
60601-1-2 are intended to be used, or just the 20 V/m test level 
called out.


On Fri, Jul 21, 2023 at 10:57 AM  wrote:

Hi Brian,

Just for your information, in Europe residential EV chargers (for
charging an EV with AC voltage), typically needs to fulfill the
requirements of EN 61851-21-2  (product standard for off-board EV
chargers).  In this standard you will find the applicable test
levels for immunity testing.  One of the tests that needs to be
performed is the radiated immunity test according EN 61000-4-3.
(This is the basic standard which specifies how a radiated
immunity test should be performed, in this test standard you find
typical test levels, however in this case the product standard is
where you should look to find the applicable test level.

If the charger will be located solely in a residential
environment, a fieldstrength of 3V/m is applicable.  For
locations other than residential 10V/m is required.  (modulation
used: 80% AM 1kHz in both cases).

Typically testing is performed in two operational modes:

 1) the charger is in charging mode

 2) the charger is in waiting mode.

20V/m is more than needed  (which is of course allowed, but not
typically done by manufacturers)

FCC  (for the US region) does not require immunity testing to be
performed. So in FCC part 15B, you’ll only find emission limits.
So, not related to your question.

I hope it helps.

Greetings,

Bart

*From:*Brian Gregory 
*Sent:* vrijdag 21 juli 2023 18:44
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* [PSES] Immunity test field strength, residential setting

 Hello colleagues,

We are building EV Chargers for residential markets (not just US)
and one of the safety applicable standards is UL 2231-2.  It
calls out  IEC 61000-4-3 for immunity testing parameters, which
states a requirement for a field strength of 20V/m.  Our EMC
expert says typically testing is "done at 3 Vrms, which is
standard for most products in residential environments."   He can
only test up to 10V, and we're hearing the same from an overseas
lab to whom our manufacturer refers.

Does FCC Part B have guidelines for field strength we can cite? 
 Can some offer this "DC guy" (aka, 60 Hz) a quick definition of
what the 20V/m represents?

I'm guessing 20 V/m is for higher density commercial
applications, aka charging stations, so we probably need an
exception for residential.

Thank you!

Colorado Brian
720-450-4933 



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Re: [PSES] FCC Part B questions

[Brent DeWitt]

I think we're bundling independent errors here.  The lab's 17025 
measurement uncertainty is independent of the EUT.  That said, you are 
certainly correct that measurement _variability_, due to the complexity 
of the EUT, generally swamps the lab MU, especially in the case you 
mention when multiple long cables exist.


On 7/12/2023 4:17 PM, Elliott Martinson wrote:


A fun thing to do if you have access to a semi-anechoic chamber is use 
lots of duct tape to make sure /absolutely/ /nothing/ changes between 
measurements other than a certain design change--one accepted long ago 
that already went into production, which cost $$$ (cable ferrites, 
wrapping cables multiple times through ferrites, various black 
magic/witchcraft-based ideas)--and end up with evidence that a pass at 
a compliance lab years ago was misattributed to an expensive design 
change instead of a new test setup. Even all the duct tape in the 
world, however, doesn’t bring the uncertainty to 0.


The standard  almost addresses this as you’re supposed to (as best as 
I can remember) adjust the EUT’s position on the turntable relative to 
the cables, which are also to be individually adjusted 
(position/orientation) to maximize emissions for each frequency “of 
interest” (along with mast height if I remember right). Try that with 
a console with 20+ cables at even one frequency… with a simplifying 
assumption that a cable can either be laid out in state “A” or state 
“B”, that’s still over 1 million combinations. Good thing for the lab 
techs (and whoever pays the labs’ hourly rates) to have some 
“uncertainty” cushion


-Elliott

*From: *Brian Kunde 
*Reply-To: *Brian Kunde 
*Date: *Tuesday, July 11, 2023 at 9:31 AM
*To: *
*Subject: *Re: [PSES] FCC Part B questions

If I may pile on late, keep in mind that measurement uncertainty is 
Plus or Minus (±). Years ago when I was with a previous company, we 
had a buy/sell piece of junk product that we were selling with our 
company's brand/name on it. It was audited in Sweden as part of their 
surveillance program and it failed by 2dB.  The test lab said they 
could not say it FAILED because 2dB was within their measurement 
uncertainty, so we could continue to ship and sell this product in 
Sweden.


Has anyone else ever experienced this?

Thanks,

The Other Brian

On Sat, Jul 8, 2023 at 8:28 AM Brent DeWitt  wrote:

Hi Brian.  It's not entirely clear which measurement range you are
asking about, but I'll assume conducted emissions in the range of
150 kHz to 30 MHz.

Short answer: You can skip QP and Avg detection if the peak
detection level is below the Avg detection limit.

No margin is "required" to pass any emissions limit. Zero dB
margin is still passing.  That said, measurement uncertainty in
that range is generally 3-4 dB, so having a passing margin greater
than that gives you some confidence that a re-test at another time
and lab will still pass.

Hope that helps.

respectfully,

Brent DeWitt
Milford, MA

On 7/8/2023 12:38 AM, Brian Gregory wrote:

 Hi there,

A question came up that I can't answer w/o a copy of Part 47.

Does the FCC report require Quasi-Peak (QP) data, or just Avg
and Peak.  When do peak readings trigger the need to report
QP?  I'm pretty sure Part 15 has AVG and QP limits listed.

Next was what sort of margin is expected in order to pass CE
emissions requirements (CISPR 16 or 32)?  Memory serves that
one wants 3dB of margin, but memories can be imperfect!

"Colorado" Brian
720-450-4933

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Re: [PSES] FCC Part B questions

[Brent DeWitt]

Every measurement uncertainty seminar I've ever been to, since the mid 
80s, has concentrated on it as a measure of the labs ability to control 
uncertainty.  In every case, from NIST to NPL, they have been adamant 
that uncertainty has _nothing_ to do with the pass/fail criteria.  The 
ironic thing is that labs would argue that, by being more rigorous an 
finding higher uncertainty, they would scare away customers who found 
less rigorous lab's smaller numbers attractive.


Obvious puns about uncertainty resisted,
Brent DeWitt, Lab Manager iRobot
Milford, MA

On 7/12/2023 11:02 AM, Patrick wrote:
what year did measurement uncertainty become a required component of 
lab accreditation?


was there massive radio interference at homes and in offices that 
suddenly ceased the year after?


asking for a friend.

On Tue, Jul 11, 2023, 10:28 Chas Grasso  wrote:

When the concept of measurement uncertainty came about, the
company I worked for at the time decided that
irrespective of the technical niceties of statistics if emission
exceeded the spec but was within the stated MU,
then that was still considered a FAIL. The difficulty came when
the emission PASSED but was within the MU.
The company decided that - even if the testhouse would not declare
the pass, the product still shipped.

In other words - life as usual.





On Tue, Jul 11, 2023 at 9:13 AM Ken Javor
 wrote:

*

 This message originated outside of DISH and was sent by:
ken.ja...@emccompliance.com

*


Not in the commercial sector, but people try this argument all
the time when failing a MIL-STD-461 limit by less than 3 dB,
on account of the measurement system integrity check has to be
within that margin.

They /never/ express such concerns when they pass within 3 dB
of the limit, however.

-- 


Ken Javor

(256) 650-5261

*From: *Brian Kunde 
*Reply-To: *Brian Kunde 
*Date: *Tuesday, July 11, 2023 at 9:31 AM
*To: *
*Subject: *Re: [PSES] FCC Part B questions

If I may pile on late, keep in mind that measurement
uncertainty is Plus or Minus (±). Years ago when I was with a
previous company, we had a buy/sell piece of junk product that
we were selling with our company's brand/name on it. It was
audited in Sweden as part of their surveillance program and it
failed by 2dB.  The test lab said they could not say it FAILED
because 2dB was within their measurement uncertainty, so we
could continue to ship and sell this product in Sweden.

Has anyone else ever experienced this?

Thanks,

The Other Brian

On Sat, Jul 8, 2023 at 8:28 AM Brent DeWitt
 wrote:

Hi Brian.  It's not entirely clear which measurement range
you are asking about, but I'll assume conducted emissions
in the range of 150 kHz to 30 MHz.

Short answer: You can skip QP and Avg detection if the
peak detection level is below the Avg detection limit.

No margin is "required" to pass any emissions limit.  Zero
dB margin is still passing.  That said, measurement
uncertainty in that range is generally 3-4 dB, so having a
passing margin greater than that gives you some confidence
that a re-test at another time and lab will still pass.

Hope that helps.

respectfully,

    Brent DeWitt
Milford, MA

On 7/8/2023 12:38 AM, Brian Gregory wrote:

 Hi there,

A question came up that I can't answer w/o a copy of
Part 47.

Does the FCC report require Quasi-Peak (QP) data, or
just Avg and Peak.  When do peak readings trigger the
need to report QP?  I'm pretty sure Part 15 has AVG
and QP limits listed.

Next was what sort of margin is expected in order to
pass CE emissions requirements (CISPR 16 or 32)? 
Memory serves that one wants 3dB of margin, but
memories can be imperfect!

"Colorado" Brian
720-450-4933

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Re: [PSES] FCC Part B questions

[Brent DeWitt]

I agree with Jim.  The measurement uncertainty I mentioned is only for 
the measurement chain.  Product uncertainty usually swamps that.  As you 
would expect, it's all about the product.  I currently work with robot 
vacuum cleaners and their docks.  No cables and battery powered is as 
simple as it gets.  I'm measured rack mount systems with 30+ cables, and 
it's a nightmare.  I would suggest discussing your product in detail 
with the test house, or a consultant of your choice, to more accurately 
evaluate your margin needs.


Brent DeWitt

On 7/8/2023 10:17 AM, Jim Bacher, WB8VSU wrote:
Brian, for margins it's not required by the standards. It is a 
"Personal Preference". I have always used and recommended 6 dB for 
prototypes / first production and 3 dB margin for production audits.


As Brent mentioned there is variation in measured levels between test 
sites. However, your product in production will also have RF emission 
variations.


All produced products need to be compliant, not just the one you 
tested. How consistent are your production units? If they are very 
consistent, then a lower margin might be Ok.


Jim Bacher




On July 8, 2023 12:41:10 AM Brian Gregory  
wrote:



 Hi there,
A question came up that I can't answer w/o a copy of Part 47.
Does the FCC report require Quasi-Peak (QP) data, or just Avg and 
Peak.  When do peak readings trigger the need to report QP?  I'm 
pretty sure Part 15 has AVG and QP limits listed.
Next was what sort of margin is expected in order to pass CE 
emissions requirements (CISPR 16 or 32)?  Memory serves that one 
wants 3dB of margin, but memories can be imperfect!

"Colorado" Brian
720-450-4933
-


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Re: [PSES] FCC Part B questions

[Brent DeWitt]

Hi Brian.  It's not entirely clear which measurement range you are 
asking about, but I'll assume conducted emissions in the range of 150 
kHz to 30 MHz.


Short answer: You can skip QP and Avg detection if the peak detection 
level is below the Avg detection limit.


No margin is "required" to pass any emissions limit.  Zero dB margin is 
still passing.  That said, measurement uncertainty in that range is 
generally 3-4 dB, so having a passing margin greater than that gives you 
some confidence that a re-test at another time and lab will still pass.


Hope that helps.

respectfully,

Brent DeWitt
Milford, MA

On 7/8/2023 12:38 AM, Brian Gregory wrote:

 Hi there,
A question came up that I can't answer w/o a copy of Part 47.
Does the FCC report require Quasi-Peak (QP) data, or just Avg and 
Peak.  When do peak readings trigger the need to report QP? I'm pretty 
sure Part 15 has AVG and QP limits listed.
Next was what sort of margin is expected in order to pass CE emissions 
requirements (CISPR 16 or 32)?  Memory serves that one wants 3dB of 
margin, but memories can be imperfect!

"Colorado" Brian
720-450-4933
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Re: [PSES] Resend of complete message on ESD thoughts

[Brent DeWitt]

I'll jump in quickly to state my opinion:

Contact discharge does not represent any "natural" mechanism I know of, 
but I prefer it because it seems to have the highest repeatability in 
revealing a device's vulnerability.


-Brent, "If I can't be 'right', I at least want to be consistent about it"

On 3/6/2023 6:40 PM, doug emcesd.com wrote:


Hi John and Chas,

I and others presented the strong evidence in the late 1990s of 
problems, including irreproducible results, and I see the results of 
these problems all the time.


 1. Many products fail because of E-field emissions from the
simulators, which is not controlled in the standard unless
recently revised. This needs to be done. I have seen many products
that fail by emissions. The emissions from many simulators are far
worse (10x or more) than any natural ESD event. There is at least
one simulator that has an emissions profile similar to a real ESD
event, the rest are over testing in a way that does not add value
as it does not correspond to what can actually happen.
 2. To get reproduceable results between simulators (which is a BIG
problem) a max di/dt specification needs to be added to the
standard as I and others proposed in the 1990s. Without this, the
standard is fatally flawed and leads to random results between
simulators. I and others run into this all the time. I can tell
you which brands will fail a good product that actually should
pass, this from the large amount of data I have generated at
considerable expense to myself. This data is presented in some of
my classes.
 3. Just because one does not see field problems in the field (I do
see such problems quite a bit) does not mean the standard is good.
*When a test is used that does not come remotely close to a real
possible event (such asa  20 kV contact discharge used in some
industries), it increases costs for everyone for no purpose.*

I have tons of data to support my points, some generated for the IEC 
in the 1990s, which should be available and more modern and voluminous 
data I generated in the last year or so at my own personal expense for 
inclusion in seminars. My personal experience also shows that agrees 
with my data.


I am very familiar with Michael King’s contributions which were very 
significant but limited by the instrumentation available at the time. 
But even in the 1990s, the data clearly showed some changes to IEC 
61000-4-2 were needed. In looking through my more recent data, there 
are patterns that show some interesting conclusions on ESD testing. I 
took the data in a way that exposed them, which we did not do in the 
1990s because we did not know back then.


I have helped my clients pass quite a few ESD and EMC tests by taking 
advantage of problems with the standards. Passing with no changes is 
good. They still officially passed by accredited labs and procedures 
but with no changes or money spent against an original fail to get 
quickly to market.


Doug

*From:* Chas Grasso 
*Sent:* Monday, March 6, 2023 7:02
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] Resend of complete message on ESD thoughts

Good points John.

On Mon, Mar 6, 2023, 7:58 AM John Woodgate  wrote:

* This message originated outside of DISH and was sent by:
j...@woodjohn.uk ***



There are two good points about 61-4-2:the test results are
repeatable and products that pass the tests rarely suffer from ESD
failures in the field. But there are, even so, unresolved issues
and doubts about the relations between the tests and actual ESD
events. Because the present standard 'works', strong evidence
would be required to support a proposal for change, and that is
not forthcoming.


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk


Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I
understand. Xunzi (340 - 245 BC)

On 2023-03-06 14:48, Chas Grasso wrote:

Don't forget the seminal research done by WMKing on this
topic. He was I believe the first to measure the fast response
of an ESD event through a metal intervening object. Also, it
is understood that the ESD test was a consensus output in an
attempt to provide repeatability within test houses. King and
Hish also produced an ESD generator that accurately replicated
the research.

The current ESD test is a committee consensus output which
tried very hard to produce a test that could be 

Re: [PSES] Apple Files Patent for EMC Testing Chamber

[Brent DeWitt]

My apologies for the typo.  I meant to type "I don't see anything that 
wouldn't be found to be "prior art"."



On 2/23/2023 6:28 PM, Ghery Pettit wrote:


Simple – Apple has the bucks and lawyers. Like you, I don’t see 
anything that isn’t prior art here, either.


Ghery

*From:* Brent DeWitt 
*Sent:* Thursday, February 23, 2023 3:23 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] Apple Files Patent for EMC Testing Chamber

I had the same thought Doug.  Maybe I need to read the patent more 
closely. I don't see anything that would be found to be "prior art".


-Brent

On 2/23/2023 5:03 PM, Douglas Powell wrote:


  Am I missing something here? Apple Files Patent for EMC Testing
  Chamber
  
<https://www.patentlyapple.com/2023/02/apple-files-patents-for-an-electromagnetic-shielding-testing-chamber-gpus-and-windows-for-future-vehicles.html>

I don't know about anyone else, but circa 2004, I was directly
involved in the construction of a EMC shielded semi-anechoic test
chamber, with cable penetrations, equipment cooling water lines,
turntable, motorized antenna mast, AND ventilation, all the while
maintaining better than 110 dB of shielding effectiveness up to 10
GHz.

How is this news, and worthy of a Patent?

-Doug

Douglas E Powell

Laporte, Colorado USA

doug...@gmail.com <mailto:doug...@gmail.com>

LinkedIn <https://www.linkedin.com/in/coloradocomplianceguy/>

(UTC -07:00) Mountain Time (US-MST)

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Re: [PSES] Apple Files Patent for EMC Testing Chamber

[Brent DeWitt]

I had the same thought Doug.  Maybe I need to read the patent more 
closely.  I don't see anything that would be found to be "prior art".


-Brent

On 2/23/2023 5:03 PM, Douglas Powell wrote:



  Am I missing something here? Apple Files Patent for EMC Testing
  Chamber
  


I don't know about anyone else, but circa 2004, I was directly 
involved in the construction of a EMC shielded semi-anechoic test 
chamber, with cable penetrations, equipment cooling water lines, 
turntable, motorized antenna mast, AND ventilation, all the while 
maintaining better than 110 dB of shielding effectiveness up to 10 GHz.


How is this news, and worthy of a Patent?

-Doug


Douglas E Powell
Laporte, Colorado USA
doug...@gmail.com
LinkedIn 

(UTC -07:00) Mountain Time (US-MST)

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Re: [PSES] Adding more than one EUT

[Brent DeWitt]

I'm being a bit flippant, but;

- If I was in my 3rd-party test house role, it stops when the customer 
says stop.
- If I am the steward of my company's product, it stops when my 
"engineering judgement" says we've "done our best to find the worst". 


Assuming, of course, that it's a DoC product for the US and EU.

Brent

On 2/18/2023 3:51 PM, Dan Roman wrote:


Back in a previous life when I worked on PCIe, VME, etc. boards that 
plugged into a chassis, we would frequently start adding cards until 
we saw no increase in emissions to satisfy compliance if a customer 
used multiples of our boards, which was often the case.  These were 
components however and to me it seems a bit murkier if an end product 
that could function standalone is used with others, especially if each 
has its own power cord.


Even in my case with the PC cards, we didn’t test multiples of every 
combination of boards we sold, it would be impossible to do.  Does the 
manufacturer of an LED light bulb need to test just one bulb or do 
they need to find the fixture that holds the most lightbulbs and test 
in that?  I don’t think so much in the same way that a server 
manufacturer tests one server and doesn’t need to find the customer 
that puts the most servers in a rack or a computer room and test that 
number of servers.  Perhaps if they are selling a rack of servers that 
uses a common power cord?


Where does it stop?

Dan

*From:*John Mcbain [mailto:johnmcb...@ieee.org]
*Sent:* Saturday, February 18, 2023 2:20 PM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG
*Subject:* Re: [PSES] Adding more than one EUT

Hi Brent -

Yes, different testing certainly would be appropriate for different 
power distribution and connection methods, so knowing ALL the details 
is very important to decide how to test.


However, one _essential_ piece of knowledge may be overlooked.  What 
exactly is the product being sold?  Marketing plays a _huge_ role in 
knowing what to test, and decisions made by Marketing AFTER the 
product is released can create non-compliant products without a single 
physical change being made. Common case - let's sell this new 
combination of equipment as a single product.


And of course, since "no changes are being made to the product" 
(wrong!) why bother telling the compliance engineer?  Been there!



Best regards,

John McBain

On Sat, Feb 18, 2023 at 7:37 AM Brent DeWitt  
wrote:


An unanswered, and critical, question is:
Do the "daisy-chained" devices draw power produced by the initial
item, or do they all have independent power supplies?

- First case: Initial unit produces DC/AC for the additional units.
- Second case: the initial unit is a simple, passive "power strip"
for the additional units.

In the first case, I would expect testing as a system, with all
units attached
In the second case, I would test a single unit.

Another implication is for radiated emissions. What is the
expected spacing between units in the typical users.

with respect,

Brent DeWitt
Milford, MA

On 2/17/2023 9:56 PM, Ken Javor wrote:

I’m finding this an extremely interesting discussion. I don’t
have anything definitive to offer, but I do have a question to
help stir the pot.

If the possibility that multiple items might be used together
and that emissions will be additive in some fashion is a
justification for testing multiple units at a time, what about
... light bulbs?

Meaning CFLs or LEDs.

My house is full of them.  It is reasonable to assume that
most homes/businesses are. Perhaps the emissions limits for
these were based on this reasonably foreseeable outcome?

Ken Javor
Phone: (256) 650-5261



*From: *John Mcbain http://johnmcb...@ieee.org>>
*Reply-To: *John Mcbain http://johnmcb...@ieee.org>>
*Date: *Fri, 17 Feb 2023 14:22:44 -0800
*To: *http://EMC-PSTC@LISTSERV.IEEE.ORG>>
*Subject: *Re: [PSES] Adding more than one EUT

Hi Derek -

Typical requirement for a unit that may be sold and used in
multiples (that is, all the units can be sold together as one
product) is you can test just one IFadding the other units
does not increase the emissions.

Of course the most practical way to determine that is to
assemble the multiple units to see what happens.  If the test
result for testing max. connected units compared to testing
only one unit shows no significant difference, then you're
good - but definitely archive those test results!

If you can't pass the test with all units connected, then
whatever you do, don't let Marketing create a multiple-unit
product to sell.  ;-)

Similarly, the

Re: [PSES] Adding more than one EUT

[Brent DeWitt]

An unanswered, and critical, question is:
Do the "daisy-chained" devices draw power produced by the initial item, 
or do they all have independent power supplies?


- First case: Initial unit produces DC/AC for the additional units.
- Second case: the initial unit is a simple, passive "power strip" for 
the additional units.


In the first case, I would expect testing as a system, with all units 
attached

In the second case, I would test a single unit.

Another implication is for radiated emissions. What is the expected 
spacing between units in the typical users.


with respect,

Brent DeWitt
Milford, MA

On 2/17/2023 9:56 PM, Ken Javor wrote:
Re: [PSES] Adding more than one EUT I’m finding this an extremely 
interesting discussion. I don’t have anything definitive to offer, but 
I do have a question to help stir the pot.


If the possibility that multiple items might be used together and that 
emissions will be additive in some fashion is a justification for 
testing multiple units at a time, what about ... light bulbs?


Meaning CFLs or LEDs.

My house is full of them.  It is reasonable to assume that most 
homes/businesses are. Perhaps the emissions limits for these were 
based on this reasonably foreseeable outcome?


Ken Javor
Phone: (256) 650-5261



*From: *John Mcbain 
*Reply-To: *John Mcbain 
*Date: *Fri, 17 Feb 2023 14:22:44 -0800
*To: *
*Subject: *Re: [PSES] Adding more than one EUT

Hi Derek -

Typical requirement for a unit that may be sold and used in multiples 
(that is, all the units can be sold together as one product) is you 
can test just one IFadding the other units does not increase the 
emissions.


Of course the most practical way to determine that is to assemble the 
multiple units to see what happens.  If the test result for testing 
max. connected units compared to testing only one unit shows no 
significant difference, then you're good - but definitely archive 
those test results!


If you can't pass the test with all units connected, then whatever you 
do, don't let Marketing create a multiple-unit product to sell.  ;-)


Similarly, the desktop PC system that James mentioned would have all 
power cords separately tested for conducted emissions as a fully 
connected system (monitor, printer, scanner, etc. attached) if it is 
a  product sold as a complete all-included system.


Best regards,
John McBain


On Fri, Feb 17, 2023 at 1:59 PM James Pawson (U3C) 
 wrote:



Hi Derek,


Is the daisy chain connection the AC supply or some other power bus?


How is 8 units daisy chained any different to 8 separate units all
on the same power bus? We are looking for individual emission
contributions from each connected unit.


If measuring conducted emissions on a desktop pc (y'know, the big
ones we had before everyone had laptops to work from home...) the
you would just measure the PC, not the monitor and printer and
scanner and modem and and and...


Just thinking aloud

All the best

James


 Lfresearch wrote 

Hi folks,



I’ve been asked to test a light fixture that has the ability to be
daisy chained up to 8 units.



When I run conducted emissions, I’m wondering if I need to insist
on having 8 units plugged in at once i.e. fully populated, OR, can
I just test one fixture at a time since that’s how the system is
likely to be used also..



Is there a legal requirement or precedent on how this should be
tested as I’m going round in circles arguing with myself here.



Thanks,



Derek.



SSCLabs,

Reno, NV.

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Re: [PSES] Dual antenna during RE test ?

[Brent DeWitt]

Brings back memories!  MANY moons ago, I ran an OATS in the foothills of 
Colorado with lots of radio and TV ambients.  Thought I'd give the two 
antenna cancellation thing a quick experiment.  I had one antenna on out 
10 meter test mast and put a second one on the edge of our 3 meter 
diameter turntable with a preamp and attenuator on one of them.  With 
that arrangement, I could adjust both the relative amplitude and phase 
of FM and TV signals over a pretty good range, to get the best null.  
After a day or so of playing around, I found that I could poke a 15-20 
dB hole in some signals, but barely change some others.  After 
scratching my head for a while, I realized that the ones I could cancel 
were almost line-of-sight from Cheyenne, and the ones I couldn't were 
from Denver.  The light went on.  I was in a narrow mountain canyon, so 
the signals from Denver had so much multi-path reflection, that whatever 
one you canceled stll left three or four others with different phase 
relationship.  With that realization, I went down to Lyons and had a beer.


On 5/6/2022 1:57 AM, Bill Owsley wrote:
Tried the dual antennas to subtract out the ambients, several times 
since the explanation was good.

About 20 years ago.  Unsat !!!



On Monday, May 2, 2022, 02:23:26 PM EDT, Ken Javor 
 wrote:



Likely a totally different application than yours, but a long time ago 
on OATS measurements, there was development of a two-antenna test 
where one was for the actual measurement, but the other was pointed 
away to pick up the ambient, and the idea was to subtract the ambient 
out, and leave only the EUT emissions.


It was controversial.

MIL-STD-826 (1964 – 1967) had radiated emission antenna set-up 
drawings showing all antennas deployed simultaneously. In the days 
when each antenna had its own receiver, if you had enough techs that 
could speed up the test significantly. It should be noted that was 
unique to MIL-STD-826 and it did not survive into MIL-STD-461.


I’m thinking in your specific application, the antennas should be 
separated by some distance, so that they don’t affect each other. What 
that separation needs to be will depend on the desired uncertainty in 
the measurement.


--

Ken Javor

(256) 650-5261

*From: *Patrick 
*Reply-To: *Patrick 
*Date: *Monday, May 2, 2022 at 2:00 PM
*To: *
*Subject: *[PSES] Dual antenna during RE test ?

Hi All -

I'm wondering if there is any academic or practical literature on the 
use of two antennas during an emissions test.  For example, research 
or experiments on the use of two DRH's above 1.0 GHz, side-by-side, 
one vertical, the other horizontal.


Have any researchers looked at this?

Are there any experimental studies?

Thank you.

-Patrick

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Re: [PSES] Chasing a specific frequency

[Brent DeWitt]

Just to add a minor note to the thread:
The easiest way I use to determine if a signal is a "pure" clock 
harmonic, is to simply punch down the RBW on the receiver/analyzer a 
bunch of times.  If it is a clock, you can reduce the RBW by a factor of 
as much as you have, and the peak amplitude won't change.


Take care,
Brent DeWitt

On 5/6/2022 12:10 AM, Bill Owsley wrote:
If you set the step function to the 63 MHz freq, and then step up, BW 
set a little wide to account for slight inaccuracy, do you find more 
emissions, energy, harmonics, at the steps ?
If there is only the one peak, and it is a clean signal, suspect an 
curious resonance.
Had one once, the trace was resonant and sang rather notably. A little 
resistance at each end worked, but oddly, it took several guesses to 
find the right value.  ps. this was a clock trace that wrapped around 
3.5 sides of circuit board near the edge.  Don't allow that to 
happen.  Not fun, interesting, but not fun.


The frequency rings a bell, but can't quite remember why.
Ethernet is 125 MHz, guess what half of that is near ?

If the observed signal is a solid shaped peak, I would first guess a 
clock of a steady sort.
If a bit wobbly, modulated, a guess is that it has data on it, or 
might be inter-modulation.
If a shape other than sine peak, wobbly or not, it might be frequency 
modulated, usually called frequency hopping, and some actually are, 
which is a mis-understanding in engineering.


pps. the spread sheet for clock harmonics is a good tool.  We had one 
long ago, that did all the divisions and multiplications.  Then an 
easy effort to look it up.
But if the developers don't give you a complete list of clocks, xtals, 
or computed and used only in a chip, The sheet will help you tell them 
what their chips are doing.
pps, that can get a bit embarrassing, since the designers don't know 
what their chips are doing and they are building this to work.  A 6 
month delay, been there, might happen before the secrets are revealed.




On Thursday, May 5, 2022, 10:08:14 AM EDT, Ken Wyatt 
 wrote:



I was just going to suggest what James already did.

You should be able to take a small-diameter H-field probe and zero in 
on the source. That may help.


If you email me directly, I’ll provide you a clock harmonic analyzer 
spreadsheet developed by my co-author, Patrick André.


Cheers, Ken

___

I'm here to help you succeed! Feel free to call or email with any 
questions related to EMC or EMI troubleshooting - at no obligation. 
I'm always happy to help!


Kenneth Wyatt
Wyatt Technical Services LLC
56 Aspen Dr.
Woodland Park, CO 80863

Contact Me! <http://www.emc-seminars.com/page1/Contact.php> New Books! 
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On May 5, 2022, at 3:16 AM, James Pawson (U3C) 
mailto:ja...@unit3compliance.co.uk>> wrote:


Hi Amund,
Narrowband or broadband noise?
If broadband and you zoom in to the noise on the analyser, is it made 
up of separate peaks? What is the spacing between the peaks?
Try using a near field probe to zoom in on the emissions 
-https://www.unit3compliance.co.uk/graphical-guide-to-emc-near-field-probing/ 
<https://www.unit3compliance.co.uk/graphical-guide-to-emc-near-field-probing/>

All the best
James
James Pawson
Managing Director & EMC Problem Solver
**
*Unit 3 Compliance Ltd*
*EMC : Environmental & Vibration : Electrical Safety : CE & UKCA : 
Consultancy*
www.unit3compliance.co.uk <http://www.unit3compliance.co.uk/>  | 
ja...@unit3compliance.co.uk <mailto:ja...@unit3compliance.co.uk>

+44(0)1274 911747  |  +44(0)7811 139957
2 Wellington Business Park, New Lane, Bradford, BD4 8AL
Registered in England and Wales # 10574298
*From:*Amund Westin <mailto:am...@westin-emission.no>>

*Sent:*05 May 2022 09:50
*To:*EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
*Subject:*[PSES] Chasing a specific frequency
During a radiated emission test, we have a problem with one specific 
frequency, 63MHz. Not exactly 63.00MHz but like 63.03406….
We have calculated all combinations of intermodulation products from 
oscillators on the pcb, but no one match the 63MHz. There are a lots 
of DC/DC converters on the board, and I suspect low switching 
frequencies (≈1MHz) may be the source and problem. How this low 
frequency signal became 63MHz noise, it must be (could be … or?) a 
combination of harmonics and layout circuitry that optimize unwanted 
antenna performance and then result in a powerful noise component at 
63MHz.
At this stage, we have not investigated the trace layouts or the 
laye

Re: [PSES] Max Hold Quasi-peak ?

[Brent DeWitt]

Like is so often said here: "It depends"

The answer lies in the nature of the EUT.  Is the peak that was measured 
a momentary and infrequent emission, a click, or a periodic emission 
that cycles on and off due to the nature of it's operation?


As a totally made up example:

If the EUT quietly gathers data for 1 minute, then processes and stores 
the data to memory for several seconds and creates higher emissions 
during that period, then the failing evaluation by the lab would seem to 
be justified.


As is often the case, a close examination of the equipment under test is 
required.


Respectfully,
Brent DeWitt

On 12/5/2021 1:45 PM, Amund Westin wrote:


Some weeks ago I went to a test lab as an observer on a CE marking 
project (IT product).


I participated on the radiated emission testing and some frequencies 
were above the limit line during the scan (peak measurement). Later 
on, the Quasi-Peak measurement lowered the values significant and 
therefore with the result Passed.


Later on, I was told that they continued the testing by 10-15 minutes 
and was logging the maximum Quasi Peak value (repetitive QP meas) on 
spike with the highest value. During these 15 minutes, one or two QP 
measurement was above the limit and the result was changed from Passed 
to Failed.


I have not seen this test procedure before. I’m familiar with just one 
QP measurement on each frequency and not Max Hold QP on each for 10-15 
minutes.


Anyone who have experienced the same? Is it a CISPR procedure or just 
some overzealous lab engineers?


Best regards

Amund

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Re: [PSES] Pure silicate paint as shielding for work areas

[Brent DeWitt]

This seems like a good candidate for the classic SE measurement method 
of using a shield room pass-thru panel as the sample, with antennas on 
both sides.  At least it wouldn't require much material to try.


Brent

On 11/19/2021 10:50 AM, Patrick wrote:

Ken-
agree with you on all points.

Charles-
is there any way to get a paint sample and run a test?  I can imagine 
a stepped approach of ...apply one coat, let it dry, measure SE, apply 
another coat, repeat...


seam treatment is a head-scratcher.   there are tried and true methods 
for existing shield technology, but this would be something new.  need 
a creative method to experiment and iterate into a solution.  Hmm


Patrick


On Thu, Nov 18, 2021, 09:29 Ken Javor > wrote:


Obvious observations.

Shielding effectiveness depends on the paint conductivity after
applied and dried.  The solid content by volume needs to be that
which achieves the desired cured/dried conductivity.

Next, the surface conductivity will facilitate some degree of
shielding effectiveness.  But you didn’t state the goal.  If one
coat doesn’t deliver the required conductivity, then maybe
multiple coats might, but whether that is practical totally
depends on the ratio of single coat SE to desired SE.

And finally, chamber SE is high-side bounded by the SE calculable
from the paint conductivity. All seams, apertures, and
penetrations must be handled in a manner to protect the SE
inherent in the paint conductivity.

Ken Javor
Phone: (256) 650-5261




*From: *"Grasso, Charles" http://charles.gra...@dish.com>>
*Reply-To: *"Grasso, Charles" http://charles.gra...@dish.com>>
*Date: *Thu, 18 Nov 2021 09:05:14 -0700
*To: *http://EMC-PSTC@LISTSERV.IEEE.ORG>>
*Subject: *[PSES] Pure silicate paint as shielding for work areas

Hello all,

We are considering the use of  pure silicate paint to shield a
room,  Does anyone have experience with using a paint like this in
this sort of application?. Obviously all the normal
rules apply for ensuring a contiguous bond - I have only a limited
idea on the difficulties that
requirement will entail!  FYI, the "spec" does not specify % by
volume of the solid content. I am guessing that 50-70% by volume
should be sufficient - does that make sense?

Thank you in advance!

-- 
Charles Grasso

Dish Technologies

 (c) 303-204-2974
(h) 303-317-5530
(e ) charles.gra...@dish.com 
(e2) chasgra...@gmail.com 
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Re: [PSES] Basic Schematic Creation Software

[Brent DeWitt]

Manny brings up a great option.  Even if you have no need for actual 
circuit simulation.  I can recommend SiMterix, LTSpice and MicroSim as 
totally free programs that will allow you to create schematics, however, 
I'm not so sure that any of those offer open/closed switch symbols.


From a purely graphic approach,"DIA" is a free alternative to Visio and 
allows structured drawings with some pre-defined electrical elements:




Fare well,
Brent DeWitt, AB1LF

On 5/20/2021 1:42 PM, Manny Barron wrote:

Hi Brian,

I have found Spice to be useful for scenarios as you describe, in my 
case for EMC/EMI analysis. The program is relatively easy to use and 
changing circuit elements and re-running an analysis is simple in my 
opinion.


There are several variations of Spice on the market today, but I'm not 
sure if you'll find a free version. Ten years ago I purchased T-Spice 
(I think that's the name) for about $500 and it worked great for 
current in-rush analysis I had to do.


Recommend doing some web searches on Spice to see what turns up, maybe 
you'll find what you're looking for, and who knows, maybe even freeware.


Regards,

Manny Barron




On Thu, May 20, 2021 at 8:53 AM Brian Kunde <mailto:bkundew...@gmail.com>> wrote:



I am in need of a simple program for creating simple schematics of
Safety Circuits in a variety of States.  I envision something that
I can easily insert door switches, relays, button switches,
e-stops, fuses, circuit breakers, etc..  It would be nice if once
laid out, I can simply click to change the state of a switch or
relay to represent different states of a Safety Function.  And
then save it off in .pdf format.

Does anyone know of some software that will do this for a low cost
or maybe Free?  This is something we will use only a few times a
year.

Thanks to all in advance for any information.

Regards,
The Other Brian


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[PSES] ESD verification

[Brent DeWitt]

I'm curious if anyone in the group has tried using an ESD verification 
target mounted on aluminum foil faced foam rather than a serious piece 
of sheet metal?  My thought is that at the FFT frequencies of rise-time 
and decay, the skin depth is going to be less than the thickness of the 
foil, so it shouldn't matter.  A half sheet of the stuff would certainly 
be cheap, light weight and I can get it today!


Experiences and opinions welcome,

Thanks,
Brent DeWitt, AB1LF

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Re: [PSES] RF absorber for EMC room

[Brent DeWitt]

Yes, but.

To be effective down to 30 MHz, "classic" carbon loaded, tapered foam 
absorbers need to be huge, on the order of 2 meters high.  That eats a 
lot of internal chamber volume.  I'm also not sure if anyone makes them 
currently.  Also, do _not_ buy old (10 year +), used absorbers!  They 
still work fine as absorbers, but tend to lose there self-extinguishing 
capability due to the migration of the retardant salts used in the 
manufacturing process for that purpose. Urethane fires are not something 
you want to experience.


Respectfully,

Brent DeWitt
iRobot
Bedford, MA

On 3/16/2021 5:13 AM, McBurney, Ian wrote:


A question for the EMC experts.

Is there an alternative rf absorber to ferrite tiles that works 
between 30MHz to 1GHz? I am thinking of the pyramidal type absorber.


This is for research for partially lining a pre compliance radiated rf 
emission EMC room.


Many thanks in advance.

Ian McBurney

Lead Compliance Engineer.

Allen & Heath Ltd.

Kernick Industrial Estate,

Penryn,

Cornwall. UK.

TR10 9LU.

Tel: 01326 370121

Email: ian.mcbur...@allen-heath.com

Allen & Heath Ltd is a registered business in England and Wales, 
Company number: 4163451. Any views expressed in this email are those 
of the individual and not necessarily those of the company. -



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Re: [PSES] SV: [PSES] Conducted emission - AC line filters makes it worse

[Brent DeWitt]

You bet!  I've done it many times.  It's not perfect, but does give you 
a rough estimate.  The only requirement is being able to butcher the 
power cord so you can get tat the individual conductors.  Putting both 
through the clamp gives you the CM. Then take either L or N and twist it 
180 degrees.  Put both in the clamp and you get the DM component.  
Again, not perfect, but a good and simple way to start understanding 
what you need for a filter.


Best regards,
Brent G DeWitt
Milford, MA


On 7/2/2020 1:57 AM, Amund Westin wrote:


I will try to get access to the product next week and do my own 
measurements for conducted emission (generic light industry limit).


The lab does only offer me a spectrum analyzer and a current clamp for 
measuring / troubleshooting. Not a LISN.


From the book «EMI troubleshooting techniques», Michel Mardiguian, 
there is a way to measure CM and DM noise with a current clamp.


I’m planning to follow that procedure and do some initial 
measurements, and then repeat the measurements after modifications.


Assume that improvements and lower levels under these measurements, 
will also be reflected when later on doing this with a LISN.


Anyone who have tried such troubleshooting technique?

Best regards / Mit freundlichen Grüßen / Mvh

*Amund Westin*

**

/Cell: (+47) 920 17 031/

/E-mail: //am...@westin-emission.no/ //

/**/

*Fra:*Grasso, Charles [Outlook]
*Sendt:* 29. juni 2020 16:40
*Til:* EMC-PSTC@LISTSERV.IEEE.ORG
*Emne:* Re: [PSES] Conducted emission - AC line filters makes it worse

Hi – This IS an interesting problem!

My question: Is the 3 –phase configures as a delta or a wye configuration?

Also – What is the AC device (power supply/motors etc..)

[Working From Home]

Charles Grasso

Crackpot Theorist

Dish Technologies

(c) 303-204-2974

(h) 303-317-5530

(e ) charles.gra...@dish.com 

(e2) chasgra...@gmail.com 

*From:*Patrick mailto:conwa...@gmail.com>>
*Sent:* Sunday, June 28, 2020 9:50 AM
*To:* EMC-PSTC@LISTSERV.IEEE.ORG 
*Subject:* Re: [PSES] Conducted emission - AC line filters makes it worse

 This message originated outside of DISH and was sent by: 
owner-emc-p...@listserv.ieee.org 



Hi Amund

This sounds like a very interesting problem.  Likely many people will 
have advice.  Maybe get lucky and someone will have had this exact 
same problem.


I'd like to help if I can.  Do you have more information on the 
failure?  What test standard and test method did you use?  How much 
over the limit?  What filters were used and how were they connected?


It could be an installation of good filters, but not wired for the 
emission type.  Also could be wrong filter type for problem?


Very interesting.

On Sun, Jun 28, 2020, 2:58 AM Amund Westin > wrote:


A 3-phase product has three internal AC driven devices.
The product fails on Conducted emission. When connecting AC
filters to
each internal AC driven devices, the emission gets even worse.

Any clue about this phenomena? Is it some kind of impedance mismatch
which derate the filters performance?

BR
Amund

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Re: [PSES] FCC regulatory statements

[Brent DeWitt]

I would interpret your radio as being compliant.  It accepts the interference just fine.  If you don't, that's another matter...Closest thing that the US has to an immunity standard.Respectfully,Brent DeWitt, AB1LF -Original Message-
From: Richard Nute 
Sent: Oct 31, 2019 4:24 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] FCC regulatory statements

 “This device complies with part 15 of the FCC Rules.  Operation is subject to the following two conditions:  (1) This device may not cause harmful interference, and  (2) this device must accept any interference received, including interference that may cause undesired operation” Hmm.  So, if the device causes harmful interference, operation is prohibited (1).   And, if the device accepts interference that causes undesired operation, operation is prohibited (2). A CFL causes undesirable interference with my radio.  So, operation of both the CFL and radio is prohibited.   Is my interpretation correct? Best regards,Rich   
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Re: [PSES] Semi-Anechoic Chamber move

[Brent DeWitt]

I used CIR Enterprises a few times.  2nd generation family business.  
They are in Colorado, but do work anywhere in the country.  Nice folks.


Brent DeWitt, AB1LF

On 8/23/2019 11:04 AM, Ken Javor wrote:
Re: [PSES] Semi-Anechoic Chamber move I cannot remember the company’ 
name, but there is an outfit COUNS that specializes in moving shield 
rooms. And there are other people who are members of this forum who 
know the company, and hopefully remember the name and contact info.


Ken Javor
Phone: (256) 650-5261




*From: *"Wiseman, Joshua" 
*Reply-To: *"Wiseman, Joshua" 


*Date: *Fri, 23 Aug 2019 14:32:35 +
*To: *
*Conversation: *Semi-Anechoic Chamber move
*Subject: *[PSES] Semi-Anechoic Chamber move

We are facing the prospects of moving our EMC lab from one building to 
another one.  I’m working on information around the impact of such a 
move.  Does anyone have any input on the cost to move a 3m chamber. 
 The walls a ceiling would need the foam and ferrite panels removed 
prior to teardown and then put back on after rebuilding.  There is a 
small control room attached as well.


Not exactly sure of dimensions, but it’s around 30’ x 20’ x 24’.

Thanks,
Josh

*Joshua Wiseman
*Systems Engineering
Staff Engineer, Product Safety/EMC
*Ortho Clinical Diagnostics
*_joshua.wiseman@orthoclinicaldiagnostics.com__<mailto:joshua.wise...@orthoclinicaldiagnostics.com> 
<mailto:joshua.wise...@orthoclinicaldiagnostics.com>
_www.orthoclinicaldiagnostics.com<http://www.orthoclinicaldiagnostics.com/> 
<http://www.orthoclinicaldiagnostics.com/>




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Re: [PSES] Automotive EMI testing

[Brent DeWitt]

Not that I'm aware of, however the method needs to be documented in the 
test plan and (usually) agreed upon by the specific automobile manufacturer.


Brent DeWitt, AB1LF

On 8/17/2019 1:10 PM, Ken Javor wrote:
Automotive EMI testing Question for folks familiar with automotive 
equipment EMI testing.


Is there anything in current standards for immunity testing saying 
that the assessment of equipment-under-test pass/fail criteria while 
undergoing immunity testing must be automated, as opposed to having a 
human being with his/her eyes glued to a meter or display?


Thank you,

Ken Javor
Phone: (256) 650-5261
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Re: [PSES] Frequency range for conducted emissions

[Brent DeWitt]

For the upper end; conducted measurements end where radiated emissions 
start.  Back in the mists of time someone decided that a ten meter 
wavelength was something that could radiated fairly efficiently from 
cables, so radiated emissions sounded like more of a risk to 
telecommunications.


The 150 kHz number is more directly related to licensed services.  The 
limit was 450 kHz in the US until harmonization with the European 
measurements.  The US limit was based on protection of the AM broadcast 
band.  The European Longwave AM band extends down to 148kHz, so I assume 
they simply rounded up to 150 kHz.


From a practical standpoint, if you stick with a 50 uH LISN, it starts 
to deviate from 50 ohms quite a bit as you go lower.


Hope that helps.

Respectfully,

Brent DeWitt, AB1LF

On 8/12/2019 4:36 PM, 06cee064502d-dmarc-requ...@ieee.org wrote:

Hello group,

Does anyone know why the conducted emissions for ITE products starts 
at 150KHz and end at 30MHz? Why not start at 120KHz or 190KHz. Why 
finish at 30 and not 40MHz?


Thank you
Peter
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Re: [PSES] IEC 61000-4-9: Section 7.3 - use of a non-conductive table

[Brent DeWitt]

Hi Richard,

 

I'm assuming that by "magnetically conductive" you mean having a significant
permeability.  That's certainly a concern, but when you introduce a
conductive but non-magnetic material in to the field, there is an
opportunity for it to act as a shorted turn on the system, so keep
conductive bits small.

 

Best regards sir!

 

Brent (headed home to Colorado) DeWitt

 

From: Richard Georgerian  
Sent: Monday, May 13, 2019 4:37 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] IEC 61000-4-9: Section 7.3 - use of a non-conductive table

 

Greeting colleagues,

 

In IEC 61000-4-9, Section 7.3 it states the following -

"Table-top EUT's shall be placed on a non-conductive table."

 

Up until now, I have always thought that "non-conductive" had meant no
metals, such as iron, steel, aluminum, copper, etc. In that meaning, the
table would then be made of wood, foam, etc. However, I have been advised
that for this particular case of impulse magnetic field immunity test, that
"non-conductive" is referring to material that should not be magnetic
conductive, such as aluminum or copper. Iron and steel would not be used, as
these are considered magnetic conductive. And therefore, an aluminum or
copper sheet would be placed on the table under the EUT.

 

The standard does not provide guidance as to the use of "non-conductive"
that would mean in essence, "should not be magnetic conductive".

 

Any guidance and insight would be most helpful.

 

Thank-you,

 

Richard Georgerian

Applications Engineer

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Re: [PSES] Question re: Measuring a signal in a noisy environment

[Brent DeWitt]

Had a customer (or two) ask the same question.  My response was always: "more than it would take to fix your product".-Original Message-
From: Manny Barron 
Sent: Apr 22, 2019 3:46 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Question re: Measuring a signal in a noisy environment

Hi David, Very well stated! I can relate to all that you've said.Except I've never had a customer want to test a product unpowered. But one time a customer pulled out his checkbook during a failing test and asked me what it would take to pass. I escorted him and his product out the door. Regards, Manny Barron  From: David Schaefer [mailto:david.schae...@element.com] Sent: Monday, April 22, 2019 8:06 AMTo: EMC-PSTC@LISTSERV.IEEE.ORGSubject: Re: [PSES] Question re: Measuring a signal in a noisy environment As another voice from the test lab side – there are problems everywhere in this industry. Accreditation isn’t a panacea to fix them, but  it should reduce the most blatant errors on the lab side. It will not fix poor auditing or accreditation practices, lack of communication between lab and manufacturer, or a manufacturer hiding problems.  Most labs strive to provide high quality testing for every customer, though there are hurdles – sales people overselling services(of course we can hit that level!), poor training, lack of equipment or damaged/degraded equipment, and so on. I’ve seen reports with 100 V/m testing done outside near a major US city, test benches made of tin foil, reports with data from the wrong product, and tests with blatantly incorrect setups. I know I’ve screwed up more than once, and it doesn’t always get caught during review. Every lab has bodies buried that an in depth assessment could find, but as previously mentioned, audits only scratch the surface.  Audits also pose a problem. I had an auditor tell me that cables should be laid out 40 cm above the floor for IEC 61000-4-3, and it took a 10 minute argument and repeated citation from the standard for them to back down. I’ve also yet to meet an auditor that can dive deep into more than one or two subject areas – those with knowledge of commercial and wireless will dive deeply into every -4-x test, while MIL STD and automotive is glossed over, if it is even looked at. Thinking back to recent audits I’ve been part of the majority of findings are paperwork issues and the rest process improvements for testing. Maybe I’m fortunate that it has been years since I was told by an auditor that testing was being done incorrectly.  For anyone who has worked in a service business, customers can be the best and worst of your experiences. There are customers that walk in the door eager to learn, and others that think they are correct, despite what the standard or regulatory body actually says. I’ve seen a customer that think EMC testing can be done with the product not powered up, and partially disassembled. Almost two years in and I still have customers say the RED doesn’t apply to their product with wifi and Bluetooth in it! Lastly, there is of course the cost factor. Some labs are perfectly willing to jump through 20 hoops to do a test just how a customer wants it, or do an hour long verification before each test. They just won’t be in business long. I’ve seen quotes from some labs(both domestic and overseas) that have huge red flags – things like 3 phase surge done in an hour, onsite RE done in an hour, or multiple wildly different products being on the test report due to ‘similarity’. Too many manufacturers will look at the bottom line of the quote and pick the cheapest option. Even if testing is completely wrong, they’ll just say ‘we checked the box for compliance, ship it!’ How do we fix these issues? On the test lab side A2LA is pushing hard for pre-test checks for every test(similar to 461’s system checks) and I think it is a great improvement. A simple comb gen measurement can ensure you’re still at least in the ballpark. I have less control over auditors or manufacturers. We can do webinars and seminars to educate our customers, and cite standards when questioned. Standards bodies can also help by more clearly defining requirements, as well as including pre-checks for quality.  Thanks, David Schaefer   From: doug emcesd.com [mailto:d...@emcesd.com] Sent: Sunday, April 21, 2019 8:47 PMTo: EMC-PSTC@LISTSERV.IEEE.ORGSubject: Re: [PSES] Question re: Measuring a signal in a noisy environment Hi Ed and the group, Accredited and not, most test labs I have dealt with have made significant errors in testing. When I see these and and say “You are not performing the test correctly.” There is always pushback and I have never lost the argument. I have also picked up a few clients that have been the victim of test lab errors and have seen lots of test problems! I also have a problem with some calibration labs for poor quality work. DougSent from my iPhoneIPhone: 408-858-4528Office: 702-570-6108Email: 

Re: [PSES] [EXTERNAL] Re: [PSES] EMI testing with ambient

[Brent DeWitt]

Using the assumption below that both signals are BB and not synchronized,
could you get away with something as simple as converting the noise
amplitude and noise plus EUT amplitude to linear terms and subtract the
noise?  I believe there is precedence in CISPR regs for this approach.

 

Brent DeWitt, AB1LF

Milford, MA

 

From: Ken Javor  
Sent: Thursday, April 11, 2019 7:23 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] [EXTERNAL] Re: [PSES] EMI testing with ambient

 

If both signal and noise are broadband and not synchronized, then they would
add rss. It would be interesting if you could trigger off the signal - if
there are two BB low duty cycle signals at the same frequency, you might be
able to time window out the noise.  You didn't say radiated or conducted
(sounds like RE), but clearly easier to do conducted because higher level
signal - maybe can use o'scope. If radiated you could likely use a current
probe around the culprit radiating cable(s) to increase the signal level to
where maybe an o'scope would work.

Ken Javor
Phone: (256) 650-5261



  _  

From: "Grasso, Charles" mailto:charles.gra...@dish.com> >
Reply-To: "Grasso, Charles" mailto:charles.gra...@dish.com> >
Date: Thu, 11 Apr 2019 23:10:51 +
To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG> >
Conversation: [EXTERNAL] Re: [PSES] EMI testing with ambient
Subject: Re: [PSES] [EXTERNAL] Re: [PSES] EMI testing with ambient

Thanks Bob - Yes I have had to use this technique occasionally. What I have
is BB + BB - hence the question.
 

Thanks!
 
Charles Grasso 
W: 303-706-5467
 

From: Sykes, Bob [mailto:bob.sy...@gilbarco.com] 
Sent: Thursday, April 11, 2019 1:00 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: Re: [PSES] [EXTERNAL] Re: [PSES] EMI testing with ambient

This message originated outside of DISH and was sent by:
owner-emc-p...@listserv.ieee.org <mailto:owner-emc-p...@listserv.ieee.org>  


Also not rocket science or breaking news (to many)...  If you are measuring
a CW NB signal in the presence of BB ambient, decreasing the Resolution
Bandwidth of the EMI receiver will generally reduce ambient signal level
while having negligible effect on the CW signal.  Of course there are limits
to this.. 
 
And yes, you are no longer using the specified CISPR RBW for the measurement
so YMMV :)

 

From: Ken Javor [mailto:ken.ja...@emccompliance.com] 
Sent: Thursday, April 11, 2019 12:01 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: [EXTERNAL] Re: [PSES] EMI testing with ambient

CAUTION: This email originated from outside of the organization. Do not
click links or open attachments unless you recognize the sender and know the
content is safe.

 

Seeing as no one has yet taken a crack at this, I will weigh in with a
non-specification opinion. Meaning this is just statistics, or math, not
wording from some officially sanctioned publication.

No rocket science here or revealed truth. Probably not telling Chas anything
he doesn't already know...

You can calculate the effect of an ambient on an existing signal at the same
frequency, but you have to decide if the signal and noise add in phase or
not.  If the ambient is just thermal noise, that is an rss type calculation,
like this:

(Measured amplitude)^2  = (Actual amplitude)^2 + (noise amplitude)^2 

If the signal and noise are in phase, then it's just a linear addition.

I only mention this latter because Chas' post says the noise is BB. He
doesn't elaborate, but that could mean impulsive noise. I'm not sure if
impulsive noise adds to a cw signal the same as thermal noise. Never tried
to measure that. Worst case you assume it adds rss.

Using Chas's values: 

If the signals do add linearly, then if the measured amplitude is 6 dB over
the limit and the noise is at the limit, that means the signal is just at
the limit.

If the signals combine rss, then if the measured amplitude is 6 dB over the
limit and the noise is at the limit, that means the signal by itself is
about 5 dB over the limit.

Ken Javor
Phone: (256) 650-5261

  _  

From: "Grasso, Charles" mailto:charles.gra...@dish.com> >
Reply-To: "Grasso, Charles" mailto:charles.gra...@dish.com> >
Date: Wed, 10 Apr 2019 18:02:50 +
To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG> >
Conversation: EMI testing with ambient
Subject: [PSES] EMI testing with ambient

Hello all - My question is regarding the validity of data taken with a high
ambient condition present.
 
Due to test configuration constraints we have high broadband noise entering
a test chamber via the cables entering the enclosure.  The bb noise is about
20MHz
wide and is hitting the FCC Class B spec. Of course I have failing data
(from the EUT) 
reported by the lab. The failing data exceeds the FCC spec by about 6dB.
 
Question: What are the conditions under which a data point is considered
in

Re: [PSES] ISO17025 Antenna Calibration

[Brent DeWitt]

Mike Howard and his folks have been calibrating antennas and probes for me
for a _really_ long time (mid-90s), across multiple companies.  I've always
found them to be consistent, competitively (or better) priced and offering
quick turn-around.

 

In the usual disclaimer:  I have absolutely nothing to gain by being a fan.
Just am.

 

Brent DeWitt

Milford, MA

 

From: Wiseman, Joshua [mailto:joshua.wise...@orthoclinicaldiagnostics.com] 
Sent: Tuesday, March 06, 2018 1:08 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ISO17025 Antenna Calibration

 

Oops, thanks for the correction.

 

Josh

 

From: Knighten, Jim L [mailto:jim.knigh...@teradata.com] 
Sent: Tuesday, March 06, 2018 12:19 PM
To: Wiseman, Joshua; EMC-PSTC@LISTSERV.IEEE.ORG
<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: RE: [PSES] ISO17025 Antenna Calibration

 

EXTERNAL SENDER: Verify links, attachments and sender before taking action

 

It's the other way around.  

They used to be Liberty labs and now they are Keysight.

 



James L. Knighten, Ph.D.

Teradata

17095 Via Del Campo

San Diego, CA 92127

858-485-2537

 

From: Wiseman, Joshua [mailto:joshua.wise...@orthoclinicaldiagnostics.com] 
Sent: Tuesday, March 06, 2018 8:43 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: Re: [PSES] ISO17025 Antenna Calibration

 

John,

 

We're using Liberty Labs (formerly Keysight). In Kimbalton, IA.  Cindy
Schechinger or Ashley Gormley (712) 773-2199

 

Josh

 

From: John Mcauley [mailto:john.mcau...@cei.ie] 
Sent: Tuesday, March 06, 2018 10:52 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: [PSES] ISO17025 Antenna Calibration

 

EXTERNAL SENDER: Verify links, attachments and sender before taking action

 

Hi

 

Can anyone suggest a US based antenna calibration facility that provides ISO
17025 accredited calibration to ANSI 63.5.  A Google search doesn't point to
obvious suppliers.

 

They must be accredited to ISO 17025. 

 

Thanks in advance

 

John McAuley

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Re: [PSES] CE Marking HDMI Cables

[Brent DeWitt]

Hi Scott,

 

Which Directives do you think should apply?

 

From: Scott Douglas [mailto:sdouglas...@gmail.com] 
Sent: Thursday, January 04, 2018 7:00 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] CE Marking HDMI Cables

 

 

I am going around with an ODM making a HDMI cable for us. Standard cable just 
has our brand logo molded in the connector shell. Cable is to be used with 
Category 4 (ITE) Equipment and is sold separately.

 

The question is CE Marked or not CE Marked. I say it must be CE Marked and they 
say not required. I have been through the directives and FAQ more than a few 
times and it seems black and white to me.

 

They say they talked to three different compliance labs, at least one of which 
is familiar to a lot of us on the west coast, and all say not required. They 
say their compliance engineers all went to the required training and they all 
say not required.

 

 

Am I the only one that thinks these HDMI cables need to be CE Marked? Or am I 
missing something? Like maybe not required today but required to be marked at 
some future date like 2019 maybe?

 

Last, assuming I am not on some good psychedelics and CE Marking is required on 
or for HDMI cables, can I get away with putting the CE Mark on the single unit 
package, like a label on the poly bag it is sealed in?

 

I thank everybody that helps answer the question and keeps me from consuming 
more of those pink pills.

 

Happy New Year to all.

Scott

 

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[PSES] EMC job opening in MA

[Brent DeWitt]

* Senior EMC Technician

*  

oUS, MA - Framingham

* Apply

* Job Description

We are seeking a talented individual with experience and long-term interest
in the EMC field. In this role, you will work with a diverse range of
product design groups including, Wireless Speakers, Wireless Headsets, Audio
for Video, and Professional Systems. You will provide test expertise and
some electrical analysis in the Electro-Magnetic Compliance (EMC) area to
various product development groups.

Responsibilities include:

* Work and communicate with EMC and design engineers to understand
product EMC specifications and requirements, including all customer,
regulatory, and Bose internal requirements.

* Coordinate and conduct extensive EMC testing at multiple stages
during product development to ensure product compliance with EMC standards.

* Set up, measure, evaluate, and document test results for a wide
variety of products during validation testing.

* Work with EMC and design engineers on troubleshooting efforts that
arise.

* Provide regular status updates to project teams.

* Continuously look for ways to improve existing test methods and
lab processes, as well as devise new test methods and develop written
procedures where needed.

Must have the following skills, knowledge and abilities:

* Strong knowledge of basic electronics, experience with electronic
measurement and reporting, excellent problem solving abilities

* Strong interest in working within the EMC field

* Experience with soldering of electronic components including SMD
parts.

* Excellent verbal and written communication skills are required

* Strong working knowledge of Microsoft Excel and Word applications.

* Ability to work independently.

* Experience with any facet of EMC, RF, or audio design is a plus.

Qualifications:  

* 5+ years of experience within field, however, equivalent
knowledge, skills, and experience will be considered.

* Associates of Science in Electrical Engineering (ASEE)

 

 

Debbie Yampolsky

Sr. Technical Recruiter

Bose Talent Management | Talent Acquisition

Phone: 508-766-4992 | Internal: 64992

debra_yampol...@bose.com  

 

 

Posted by:

 

Brent G DeWitt
Senior EMC Design Engineer

Bose Corporation

The Mountain Rd, MS 450

Framingham, MA 01701

508-766-1494


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Re: [PSES] God EMC practice

[Brent DeWitt]

I agree with Jim that your calculated measurement uncertainty is the minimum
margin that one should apply.  This could be doubled by assuming the second
assessing laboratory had the same uncertainty, but in the opposite
direction!  In practice, I believe that the products cabling, and therefore
the setup uncertainty, may become dominant.  When I perform radiated
emissions measurements on a product with multiple cables, I observe a wide
span of potentially "interesting" emissions on the SA/receiver, then grab
the entire bundle of cables and simply toss them randomly.  If things wiggle
by a couple of dB, I move on.  If things swing by ten dB, I've got my work
cut out for me to maximize and I advise the customer to take a much more
generous approach to their margin requirements.

 

Brent G DeWitt
Milford, MA

 

 

 

From: Knighten, Jim L [mailto:jim.knigh...@teradata.com] 
Sent: Friday, September 01, 2017 12:05 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] God EMC practice

 

A good practice is to use your calculated measurement uncertainty for
emissions as your minimum margin requirement.

That will often put you in the 3-4 dB range.

 

Jim

 



James L. Knighten, Ph.D.

Teradata

17095 Via Del Campo

San Diego, CA 92127

858-485-2537

 

From: Kim Boll Jensen [mailto:k...@bolls.dk] 
Sent: Friday, September 01, 2017 6:01 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG  
Subject: [PSES] God EMC practice

 

Hi

 

One of our customers want to know if there are some good practice for
emission compliance. I normally recommend 3 dB margin, but I don't have any
reference to why this is OK.

 

I know that some companies have internal rules for 3 or even 6 dB margin to
compensate for production deviations and for many years ago VDE did have
some rules like that.

 

Does anyone have some good references on this subject?

 

Best regards,

 

Mr. Kim Boll Jensen

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Re: [PSES] Surge Suppression - Dos, and Don'ts

[Brent DeWitt]

In my college summers, I worked as a radio technician for the Sierra National 
Forest in California.  To make a _very_ long set of stories short, the behavior 
of high altitude lightning and antennas cannot be predicted, only analyzed 
after the fact.

 

Brent DeWitt, AB1LF

Milford, MA

 

From: John Woodgate [mailto:jmw1...@btinternet.com] 
Sent: Wednesday, August 30, 2017 4:23 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Surge Suppression - Dos, and Don'ts

 

There's noah way to prevent such arking.

 

With best wishes John Woodgate

3 Bramfield Road East, RAYLEIGH Essex SS6 8RG UK OOO – Own Opinions Only

 <http://www.jmwa.demon.co.uk/> www.jmwa.demon.co.uk J M Woodgate and 
Associates 

 

Beware averages! They hide or discard data, and may distort it (them?).

 

 

From: Jim Bacher [mailto:j.bac...@ieee.org] 
Sent: Wednesday, August 30, 2017 8:43 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: Re: [PSES] Surge Suppression - Dos, and Don'ts

 

Brian, the following is just general lightning info. 

 

Many years ago I posted a story about what can happen when a MOV failed along 
with a improper electrical ground in the service panel and a miss wired 
electrical outlet. It should be findable in the list archive. 

 

Being a ham radio operator at the last house my tower was hit at least once a 
year and would have equipment damage. However once I grounded and bonded things 
correctly, there was no more damage. During the last strike to cause damage, it 
arked over between all three wires going to the radios, but not at the same 
outlet. I had a two to 6 plug outlet plugged into the wall. It arked on the 
wall outlet and on the front surface of the multiple outlet device. It just 
about permanently welded the two items together. So as Rich said there are 
things that limit the voltages. 

 

What I have learned over the years, it is how the building is grounded and how 
the grounds are bonded together that makes the difference in equipment survival 
of a lightning strike. It is far more important than equipment design to 
survive lightning. 

 

A good book on proper grounding and bonding was just published by the ARRL. It 
is called Grounding and Bonding for the Radio Amateur. It also happens to have 
safety related information in it. 

Jim 

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Re: [PSES] Quasipeak definition

[Brent DeWitt]

The difference between resolution and accuracy is pretty intuitive to those 
(old farts) who have lived through the transition from analog meters and slide 
rules to digital meters and calculators.  It is an important differentiation to 
be passed on to  folks who haven’t thought about it.

 

Brent DeWitt, AB1LF

Milford, MA

 

From: Cortland Richmond [mailto:k...@earthlink.net] 
Sent: Monday, July 31, 2017 10:12 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Quasipeak definition

 

https://www.amazon.com/Tekpower-TP188-Pocket-size-Analog-Multimeter/dp/B00064CH6A

Eh?

I got some, old and recent, and I used them once to show  folks it was their 
14-digit $XX,000, buss-controlled remote multimeter that had them (planless and 
clueless) testing everything in sight for WEEKS.


Cortland --  WV6, KN4, W9,W1,DL4,DA1>>>KA5S




-Original Message- 
From: "Kunde, Brian" 
Sent: Jul 31, 2017 3:39 PM 
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>  
Subject: Re: [PSES] Quasipeak definition 




I have a Classic 1948 John Deere “M” tractor. I cannot measure the battery 
voltage (to see if the generator is charging the battery) while the engine is 
running because the emissions from the ignition is so bad it causes by DMM to 
malfunction.  

 

The Other Brian

 

From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] 
Sent: Monday, July 31, 2017 3:26 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: [BULK] Re: [PSES] Quasipeak definition
Importance: Low

 

Yeah, I have to fix the ignition in my ‘69 right now.  Maybe I’ll replace the 
condenser while I’m at it.

-Dave

 

From: Ghery S. Pettit [mailto:n6...@comcast.net] 
Sent: Monday, July 31, 2017 2:39 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: Re: [PSES] Quasipeak definition

 

True enough, but there are still automobiles out there with old, noisy, 
ignition systems.  Heard an old VW Beetle go by lately?  And to think, someone 
built an OATS near a freeway years ago.  What were they thinking?

 

Fortunately, the ignition system in the plane I’m flying to dinner later this 
afternoon is well suppressed.  We still use AM radios in airplanes for 
communications.  

 

Ghery S. Pettit

 

From: John Woodgate [mailto:jmw1...@btinternet.com] 
Sent: Monday, July 31, 2017 11:34 AM
To: 'Ghery S. Pettit'; EMC-PSTC@LISTSERV.IEEE.ORG 
<mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: RE: [PSES] Quasipeak definition

 

Do we have any products these days that produce such emissions?  I’m not sure 
that a 10 kHz repetition rate ever occurred anyway. For an ignition system, 
3000 RPM and 4 four-stroke cylinders only gives 600 Hz.

 

With best wishes DESIGN IT IN! OOO – Own Opinions Only

www.jmwa.demon.co.uk <http://www.jmwa.demon.co.uk/>  J M Woodgate and 
Associates Rayleigh England

 

Sylvae in aeternum manent.

 

From: Ghery S. Pettit [mailto:n6...@comcast.net] 
Sent: 31 July 2017 19:16
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: Re: [PSES] Quasipeak definition

 

The QP detector was designed in the 1930s to simulate the response of the human 
ear to impulsive interference.  The classic example at the time was the 
interference from ignition systems in automobiles to AM broadcast receivers, 
both in the car and nearby.  A single click is well filtered by the ear and 
brain, but as the repetition rate goes up the perceived annoyance and 
interference goes up.  By the time the repetition rate has reached 10 kHz the 
ear/brain combination is really annoyed and the quasi-peak detector and a peak 
detector respond about the same.

 

Hope this helps.

 

Ghery S. Pettit

 

 

From: Paasche, Dieter [mailto:dieter.paas...@christiedigital.com] 
Sent: Monday, July 31, 2017 7:35 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: [PSES] Quasipeak definition

 

How would you define the Quasipeak detector to somebody that is not EMC 
knowledgeable. 

 

 

Sincerely, 

 

Dieter Paasche

Senior Product Developer, Electrical

CHRISTIE

809 Wellington Street North

Kitchener, ON N2G 4Y7

Phone: 519-744-8005 ext.7211

www.christiedigital.com <http://www.christiedigital.com/> 

 

This e-mail message (including attachments, if any) is confidential.  Any 
unauthorized use, distribution or disclosure is prohibited.  If you have 
received this e-mail message in error, please notify the sender by reply e-mail 
or telephone and delete it and any attachments from your computer system and 
records.

 

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Re: [PSES] Quasipeak definition

[Brent DeWitt]

Before even my time, but I was told that it was modeled after the classic
"VU" meter used in sound recording, and for the same reason that Ghery
mentions below.

 

Brent DeWitt, AB1LF

Milford, MA

 

From: Ghery S. Pettit [mailto:n6...@comcast.net] 
Sent: Monday, July 31, 2017 2:16 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Quasipeak definition

 

The QP detector was designed in the 1930s to simulate the response of the
human ear to impulsive interference.  The classic example at the time was
the interference from ignition systems in automobiles to AM broadcast
receivers, both in the car and nearby.  A single click is well filtered by
the ear and brain, but as the repetition rate goes up the perceived
annoyance and interference goes up.  By the time the repetition rate has
reached 10 kHz the ear/brain combination is really annoyed and the
quasi-peak detector and a peak detector respond about the same.

 

Hope this helps.

 

Ghery S. Pettit

 

 

From: Paasche, Dieter [mailto:dieter.paas...@christiedigital.com] 
Sent: Monday, July 31, 2017 7:35 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> 
Subject: [PSES] Quasipeak definition

 

How would you define the Quasipeak detector to somebody that is not EMC
knowledgeable. 

 

 

Sincerely, 

 

Dieter Paasche

Senior Product Developer, Electrical

CHRISTIE

809 Wellington Street North

Kitchener, ON N2G 4Y7

Phone: 519-744-8005 ext.7211

 <http://www.christiedigital.com/> www.christiedigital.com

 

This e-mail message (including attachments, if any) is confidential.  Any
unauthorized use, distribution or disclosure is prohibited.  If you have
received this e-mail message in error, please notify the sender by reply
e-mail or telephone and delete it and any attachments from your computer
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Re: [PSES] application of CISPR 32 to EUTs with integrated radio transmitters

[Brent DeWitt]

I can say, from personal experience, that high speed I2S bus communications
with a modularly approve intentional radiator makes a significant change in
the unintentional emissions.  It may be/has been necessary to use a band
notch filter at the fundamental intentional frequency to keep from
overloading the measurement receiver during the investigation though.

In a perfect world, it might be possible to communicate with the intentional
radiator at full speed, but with vastly reduced transmit power, which would
seem to serve the same purpose.

Just another thought,
Brent

-Original Message-
From: T.Sato [mailto:vef00...@nifty.com] 
Sent: Friday, July 21, 2017 2:10 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] application of CISPR 32 to EUTs with integrated radio
transmitters

Hello members,

I want to hear of your opinion - while emission measurement for CISPR 32,
integrated radio transmitters must transmitting?


Although the standard is not clear whether radio transmitter can be set off
in emission measurement, I believed we can set radio transmitter off, as:

- CISPR 32 said "The radiated emission requirements in this standard are not
intended to be applicable to the intentional transmissions from a radio
transmitter as defined by the ITU, nor to any spurious emissions related to
these intentional transmissions."

- If non-transmitter function of the equipment (such as CPU clock and
harmonics) generates emissions in the frequency band of the intentional
transmission of the transmitter (such as 2.4 to 2.5 GHz), I think we should
apply the emission limits as the emissions are not related to the
intentional transmissions. However, it is difficult to measure such
emissions in presence of the intentional transmission.

- The standard says "Compliance can be shown by measuring the EUT's
emissions when operating its functions simultaneously, individually in turn,
or any combination thereof." So, even if emissions from the transmitter
function must also be considered in the standard, it should permissible to
test non-transmitter function of the equipment while transmitter is set off.

- Then, if the transmitter function of the equipment is tested while all the
other functions are set off, all the emissions measured are those caused by
the transmitter.


However, I heard of strong opinions that the emission measurement must be
run while the integrated radio transmitter is transmitting, and all the
emissions in the frequency bands of intended transmissions and those
harmonics should be simply ignored.


What do you think about this?

Regards,
Tom

--
Tomonori Sato  
URL: http://t-sato.in.coocan.jp

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Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use]

[Brent DeWitt]

Agreed Ken.  In this case the e-field conversion is irrelevant, and the
specified antenna factor is what it is.  

 

From: Ken Javor [mailto:ken.ja...@emccompliance.com] 
Sent: Monday, February 27, 2017 11:11 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General
Use]

 

If we go all the way back to the OP:

The customer has requested an extended magnetic field emission test over the
range 100kHz to 2MHz with a limit defined in dBpT.
The antenna to be used is an EMCO 6512 which has it correction factors
provided in dBS/m which the emission software used does not recognise.
So is there a conversion factor that enables the right correction factor to
be entered or is the conversion factor only used once a result is obtained??


We can see that whether we are in the far field or not doesn't matter at
all.

If we were using an electric field probe (say a 41" rod) to measure to a
limit expressed in dBuA/m or dBpT, then we would absolutely have to make an
assumption about the impedance of the wave in order to use a pure electric
field measurement to get at magnetic field characterization.

But that is not the case: we are using a shielded loop which not only
inherently measures the magnetic field, but rejects the electric field.  So
we have a limit expressed in units of magnetic flux density, which in air is
directly proportional to magnetic field (the 2 dB factor discussed
previously) and we have a loop antenna factor that gets us from the EMI
receiver measured rf potential to the magnetic field impinging on the loop
that induced it.

Problem solved; case closed.

P.S.  For any who aren't convinced or don't follow the logic, look at the
antenna factors here:

http://www.ets-lindgren.com/charts/6512

Both factors are the same except for the 51.5 dB ohm offset, discussed
previously and both clearly exhibit the Faraday Law response of a loop to a
magnetic field as a function of increasing frequency. One can even derive
the loop inductance by looking at where the Faraday Law proportionality to
frequency flattens out: that is where the 50 ohm receiver impedance begins
to load the inductive output impedance of the loop.  It is not the magnetic
antenna factor that is in question; it is the electric field antenna factor
that makes the assumption of a plane wave. The magnetic field will be
measured precisely; the electric field measured using this loop is a
guesstimate based on a far-field assumption.

Ken Javor
Phone: (256) 650-5261



> From: Cortland Richmond <k...@earthlink.net <mailto:k...@earthlink.net> >
> Reply-To: <k...@earthlink.net <mailto:k...@earthlink.net> >
> Date: Mon, 27 Feb 2017 21:13:53 -0500
> To: <EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> >
> Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions
[General 
> Use]
> 
> On 2/27/2017 7:53 PM, Brent DeWitt wrote:
>> I think Ken's rational makes sense to me, since the 51.5 is derived from 
>> 20*log(377).
>> 
>> 
> Sure, but now we're back to how close we are -- wavelengths -- to the
emitter. 
> 20*log(??)
> 
> Low frequencies can be tricky,  and I once had to double-check a test 
> lab (not yours) results at a vendor, dragging the EUT out to their 
> parking lot then wheeling a cart with a 6510 loop antenna, battery, AOR 
> AR5000 receiver and RMS voltmeter [all mine] away to see  how fast the 
> signal dropped with distance compared to 3m.
> 
> A fun time was NOT had, but I probably came across as a mad scientist. 
> Again. At least no one ran out of a chamber...
> 
> 
> Cortland Richmond KA5S
> 
> -
> 
> This message is from the IEEE Product Safety Engineering Society emc-pstc 
> discussion list. To post a message to the list, send your e-mail to 
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well-used 
> formats), large files, etc.
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-
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Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use]

[Brent DeWitt]

MANY years ago when I ran the Amador lab in Colorado, we had a well-known RFID 
customer whose tags read at 150 kHz.  Measurement distance for the FCC limit 
was 300 meters.  It just happened that the far corner of our 8-acre property 
was very close to 300 meters as measured by my mountain bike's odometer (before 
cheap accurate GPS).  Honda generator, R loop and receiver in tow, I made 
measurements at 300, 100, 30 and 10 to establish the fall off curve.  It was 
close to 60 dB/decade and the FCC accepted my curve for subsequent 
measurements.  "Near field" is a very long distance at that frequency!


Brent G DeWitt, AB1LF
Milford, MA



-Original Message-
From: Cortland Richmond [mailto:k...@earthlink.net] 
Sent: Monday, February 27, 2017 9:14 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use]

On 2/27/2017 7:53 PM, Brent DeWitt wrote:
> I think Ken's rational makes sense to me, since the 51.5 is derived from 
> 20*log(377).
>
>
Sure, but now we're back to how close we are -- wavelengths -- to the emitter. 
20*log(??)

Low frequencies can be tricky,  and I once had to double-check a test lab (not 
yours) results at a vendor, dragging the EUT out to their parking lot then 
wheeling a cart with a 6510 loop antenna, battery, AOR
AR5000 receiver and RMS voltmeter [all mine] away to see  how fast the signal 
dropped with distance compared to 3m.

A fun time was NOT had, but I probably came across as a mad scientist. 
Again. At least no one ran out of a chamber...


Cortland Richmond KA5S

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Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use]

[Brent DeWitt]

I think Ken's rational makes sense to me, since the 51.5 is derived from 
20*log(377).  

Brent DeWitt, AB1LF
Milford, MA



-Original Message-
From: Macy [mailto:m...@basicisp.net] 
Sent: Monday, February 27, 2017 2:54 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use]

Accuracy within 1%, if measured outside the source loop by 3X, which is like 
'far field'

--- ken.ja...@emccompliance.com wrote:

From: Ken Javor <ken.ja...@emccompliance.com>
To:   EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions [General Use]
Date: Mon, 27 Feb 2017 13:36:12 -0600

It's valid in the absence of a magnetic material (relative permeability = 1).  
The 51.5 dB factor is based on the far field.

Ken Javor
Phone: (256) 650-5261



> From: John Woodgate <jmw1...@btinternet.com>
> Reply-To: John Woodgate <jmw1...@btinternet.com>
> Date: Mon, 27 Feb 2017 18:07:27 -
> To: <EMC-PSTC@LISTSERV.IEEE.ORG>
> Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions 
> [General Use]
> 
> I doubt that, because it's valid at audio frequencies, which 
> undoubtedly means 'near field'.
> 
> With best wishes DESIGN IT IN! OOO   Own Opinions Only 
> www.jmwa.demon.co.uk J M Woodgate and Associates Rayleigh England
> 
> Sylvae in aeternum manent.
> 
> 
> -Original Message-
> From: Cortland Richmond [mailto:k...@earthlink.net]
> Sent: Monday, February 27, 2017 6:02 PM
> To: EMC-PSTC@LISTSERV.IEEE.ORG
> Subject: Re: [PSES] CORRECTION (wrong page) Passive Loop Emissions 
> [General Use]
> 
> On 2/27/2017 12:23 PM, John Macaulay wrote:
>> The difference between dB(pT) and dB( A/m) is 2 dB.
>> 
>> dB(pT) -2 = dB( A/m)
> 
> This is
> 
> 
> true only in the Far Field.
> 

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Re: [PSES] Passive Loop Emissions [General Use]

[Brent DeWitt]

S/m does actually make sense (to me) as the antenna factor units for getting
magnetic field strength.  Since the input to our SA or receiver measures
voltage, we get back to current by multiplying the voltage times the
conductivity, or 1 over the impedance.  That doesn't directly get you to
Teslas, but Amps/m.

 

Brent G DeWitt, AB1LF
Milford, MA

 

 

 

 

From: Ed Price [mailto:edpr...@cox.net] 
Sent: Monday, February 27, 2017 5:35 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Passive Loop Emissions [General Use]

 

Ralph:

 

I'm afraid that your explanation didn't get through to me.

 

When I think of an electric field, I think of two voltage levels separated
by a distance, so Volts per meter seems very descriptive. For instance, two
plates, one meter apart, with one plate at 5 Volts and the other plate at 15
Volts, yields a field strength of 10 Volts per meter.

 

Going logarithmic is simply a convenience for thinking about widely
differing voltage levels, so again, very straight forward. Of course, you
have to set a reference foe the log scale, so Volts or microvolts are
equally valid.

 

OTOH, mho/cm for a field is pretty obscure to me. Who uses that metric, and
how? 

 

Ed Price
WB6WSN
Chula Vista, CA USA

 

It's about as obscure as using "dBuV/m" for field strength

 

Ralph McDiarmid

Product Compliance

Engineering

Solar Business

Schneider Electric

 

 

From: Ed Price [  mailto:edpr...@cox.net]

Sent: Monday, February 27, 2017 5:37 AM

To:   EMC-PSTC@LISTSERV.IEEE.ORG

Subject: Re: [PSES] Passive Loop Emissions [General Use]

 

Andrew:

 

I thought that S/m was a unit of electrical conductivity, defined as 0.01
mho/cm. This seems like a useless unit for magnetic field strength.

 

I did find one site:

 

 

http://www.mdltechnologies.co.uk/wp-content/uploads/2012/05/6512-datasheet.p
df

 

which provides a side-by-side chart for "dBS/m" and Electric Field Strength
in "dB/m". At 10 kHz, the antenna factor in db/m is about 86 dB, while the
antenna factor in dBS/m is about 35 dB.

 

This sounds like the old relationship of magnetic field strength, in dBuA/m,
to electric field strength, in dBuV/m, of 51.5 dB.

 

Ed Price

WB6WSN

Chula Vista, CA USA

 

-Original Message-

From: Price, Andrew (Leonardo, UK) [

mailto:andrew.p.pr...@leonardocompany.com]

Sent: Monday, February 27, 2017 4:16 AM

To:   mailto:EMC-PSTC@LISTSERV.IEEE.ORG

Subject: [PSES] Passive Loop Emissions [General Use]

 

Hi All

 

I need some help in obtaining the correct result.

 

The customer has requested an extended magnetic field emission test over the
range 100kHz to 2MHz with a limit defined in dBpT.

The antenna to be used is an EMCO 6512 which has it correction factors
provided in dBS/m which the emission software used does not recognise.

So is there a conversion factor that enables the right correction factor to
be entered or is the conversion factor only used once a result is obtained??

 

Regards

Andy

 

 

 Andrew Price

 Land & Naval Defence Electronics Division

 Prinicpal Environmental Engineer (EMC)

 

 Leonardo MW Ltd

 Sigma House, Christopher Martin Rd, Basildon SS14 3EL, UK

 Tel  EMC LAB : +44 (0)1268 883308

 Mobile: +44 (0)7507 854888

 

mailto:andrew.p.pr...@leonardocompany.com%3cmailto:andrew.p.price@leonardoco
mpany.com>

 leonardocomapany.com

HELICOPTERS / AERONAUTICS / ELECTRONICS, DEFENCE AND SECURITY SYSTEMS /
SPACE

 

* Please consider the environment before printing this email.

 

 

 

 

Leonardo MW Ltd

Registered Office: Sigma House, Christopher Martin Road, Basildon, Essex
SS14 3EL A company registered in England & Wales.  Company no. 02426132



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 mailto:emc-p...@ieee.org>

 

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Attachments are not permitted but the IEEE PSES Online 

Re: [PSES] lowest emissions 4k TV?

[Brent DeWitt]

Thank you for the clarification Ghery.

-Original Message-
From: Ghery S. Pettit [mailto:n6...@comcast.net] 
Sent: Saturday, January 14, 2017 4:57 PM
To: 'Brent DeWitt' <bdew...@ix.netcom.com>; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: [PSES] lowest emissions 4k TV?

The 4th paragraph of CISPR 32, Edition 1.0, Article D.1.1 states:

"Arrangements such as placing AE below the RGP or placing AE outside the
measurement area when it is normally located distant from the EUT may be
used to limit the effects of adverse AE emissions or to reduce measurement
time, as long as the arrangement can be shown not to reduce the emissions
measured from the EUT."

Note that this refers to AE that is normally located distant from the EUT.
AE that is normally located adjacent to the EUT should be co-located with
the EUT.  See the 2nd paragraph of D.1.1.

I don't see a conflict between CISPR 32 and ANSI C63.4 in this area.

Ghery S. Pettit



-Original Message-----
From: Brent DeWitt [mailto:bdew...@ix.netcom.com]
Sent: Friday, January 13, 2017 5:01 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

It seems that there is a potential conflict between CISPR 32 and ANSI C63.4
with respect to AE/support equipment.  CISPR 32, as I remember, specifically
says to minimize the emissions from the AE/support equipment while C63.4
does have the support equipment in the test environment.  Ghery Pettit is
more qualified to comment, but I believe there is work going on to reconcile
the two.

Brent DeWitt, AB1LF
Milford, MA

-Original Message-
From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Thursday, January 12, 2017 7:20 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

Not proffering a solution here, but the amount of traffic on this topic has
surprised me. Back in the day when most testing was on an OATS, I would have
understood the concerns expressed, but nowadays most testing is performed in
a SAC simulating an OATS. With the latter it is simple to use any
off-the-shelf device in an external chamber just as the appropriate load
interface for the test sample, and provide filtering external to the chamber
necessary to clean up any emissions that could pollute the test chamber
ambient. With a shielded cable, it might be as simple as running it through
a stuffing tube and grounding out the rf current running external to the
shield. Or there could be a high quality shielded cable used in the test
chamber, which connects to a bulkhead-mounted and grounded adapter, and
external to the chamber, the noisy support equipment and any crummy cable
can be used.

Lots of possible variations, but the point is that with a SAC, we don't have
to be near as picky about the support equipment.

Ken Javor
Phone: (256) 650-5261


> From: Ralph McDiarmid <ralph.mcdiar...@schneider-electric.com>
> Reply-To: Ralph McDiarmid <ralph.mcdiar...@schneider-electric.com>
> Date: Thu, 12 Jan 2017 20:59:57 +
> To: <EMC-PSTC@LISTSERV.IEEE.ORG>
> Conversation: [PSES] lowest emissions 4k TV?
> Subject: Re: [PSES] lowest emissions 4k TV?
> 
> I wonder if RF current on the coax coming in to the cable box then
radiates
> from the HDMI cable?   All that overhead cable strung through residential
> neighborhoods must pick up a lot of RFI on its outer braid.
> 
> Ralph McDiarmid
> Product Compliance
> Solar Business
> Schneider Electric
> 
> -
> 
> This message is from the IEEE Product Safety Engineering Society 
> emc-pstc discussion list. To post a message to the list, send your 
> e-mail to <emc-p...@ieee.org>
> 
> All emc-pstc postings are archived and searchable on the web at:
> http://www.ieee-pses.org/emc-pstc.html
> 
> Attachments are not permitted but the IEEE PSES Online Communities 
> site at http://product-compliance.oc.ieee.org/ can be used for 
> graphics (in well-used formats), large files, etc.
> 
> Website:  http://www.ieee-pses.org/
> Instructions:  http://www.ieee-pses.org/list.html (including how to
> unsubscribe)
> List rules: http://www.ieee-pses.org/listrules.html
> 
> For help, send mail to the list administrators:
> Scott Douglas <sdoug...@ieee.org>
> Mike Cantwell <mcantw...@ieee.org>
> 
> For policy questions, send mail to:
> Jim Bacher:  <j.bac...@ieee.org>
> David Heald: <dhe...@gmail.com>

-

This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<emc-p...@ieee.org>

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at
http://product

Re: [PSES] lowest emissions 4k TV?

[Brent DeWitt]

I'd add that the cable must transition from the round cable with four
individually shielded twisted pairs to the defined rectangular HDMI
connector.  There seem to be plenty of ways to get that right or wrong as
well.

Brent

-Original Message-
From: ce-test, qualified testing bv - Gert Gremmen
[mailto:g.grem...@cetest.nl] 
Sent: Saturday, January 14, 2017 4:57 AM
To: Brent DeWitt <bdew...@ix.netcom.com>; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: [PSES] lowest emissions 4k TV?

Exactly :
Once the signal is unbalanced (whatever the reason) only shielding can
attenuate the emissions.
But any unbalance is caused by the EUT at the  sending or  at the receiving
end, not by the cable.


Gert Gremmen


-Oorspronkelijk bericht-
Van: Brent DeWitt [mailto:bdew...@ix.netcom.com]
Verzonden: zaterdag 14 januari 2017 2:17
Aan: EMC-PSTC@LISTSERV.IEEE.ORG
Onderwerp: Re: [PSES] lowest emissions 4k TV?

I did some experiments with equipment (Blu-Ray players and TVs) that showed
that the introduction of an off-the-shelf, poorly constructed, short, cable
to cable adapter caused a 25 dB increase in radiated emissions at 742.5 MHz
in 1080P HDMI.  The slightest introduction of skew/imbalance on the signal
combined with a non-ideal shield system introduces enough CM noise back onto
the outside of the shield to cause problems.  It takes only a very
percentage of the HDMI specified differential current drive to translate to
CM to make a 1.5 meter cable shield look like a pretty efficient antenna.

Brent DeWitt, AB1LF
Milford, MA

-Original Message-
From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com]
Sent: Friday, January 13, 2017 12:19 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

" I suspect this is just equipment originated CM current, that cannot be
cured with a better cable; but needs a better equipment CM design. (Or a
bunch of heavy ferrites)."

I suspect that is the crux of the issue, as it is for many ports on all
kinds of products.


Ralph McDiarmid
Product Compliance
Solar Business
Schneider Electric




-Original Message-
From: ce-test, qualified testing bv - Gert Gremmen
[mailto:g.grem...@cetest.nl]
Sent: Friday, January 13, 2017 1:01 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

Exactly. Nowadays it's easy to filter high speed ports, and in the case of
shielded cable this is even more easy.
One aspect that can be a problem is cable length. USB and HDMI are limited
in length, and in large rooms that can be a problem, needing repeaters, that
can form  a new problem themselves.

About the cable radiating: If the signal arrives correctly at the end in an
approved cable, the cable is not radiating. I mean it's not the mere fact
that data is running that make the cable radiate.  That is why these cable
are approved and characterized. A radiating signal cable (if due to the
signal) has problems with signal transfer also, especially at this data
rates. In the case of HDMI the external screen is not needed to protect the
signal as the data internally is grouped and internally screened (3 or 5
groups).
I suspect this is just equipment originated CM current, that cannot be cured
with a better cable; but needs a better equipment CM design. (Or a bunch of
heavy ferrites).

Regards,

Ing. Gert Gremmen
Approvals manager




+ ce marking of electrical/electronic equipment Independent Consultancy 
+ Services Compliance Testing and Design for CE marking according to
+ EC-directives:
  - Electro Magnetic Compatibility 2014/30/EC
- Electrical Safety 2014/35/EC
- Radio & Telecommunication Terminal Equipment 99/5/EC

Web:    www.cetest.nl  (English) www.ce-test.nl (Dutch) www.cetest.fr (under
construction)
Phone :  +31 10 415 24 26
---
This e-mail and any attachments thereto may contain information that is
confidential and/or protected by intellectual property rights and are
intended for the sole use of the recipient(s) named above. 
Any use of the information contained herein (including, but not limited to,
total or partial reproduction, communication or distribution in any form) by
persons other than the designated
recipient(s) is prohibited. If you have received this e-mail in error,
please notify the sender either by telephone or by e-mail and delete the
material from any computer. 
Thank you for your co-operation.

-Original Message-
From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Friday 13 January 2017 04:27
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

If I am qualifying a device that connects through a cable to this TV, but
not the TV itself, why would it physically have to be part of the set-up in
the test chamber? Why could it not simply be support equipment in an
adjacent chamber, providing the proper 

Re: [PSES] lowest emissions 4k TV?

[Brent DeWitt]

I did some experiments with equipment (Blu-Ray players and TVs) that showed
that the introduction of an off-the-shelf, poorly constructed, short, cable
to cable adapter caused a 25 dB increase in radiated emissions at 742.5 MHz
in 1080P HDMI.  The slightest introduction of skew/imbalance on the signal
combined with a non-ideal shield system introduces enough CM noise back onto
the outside of the shield to cause problems.  It takes only a very
percentage of the HDMI specified differential current drive to translate to
CM to make a 1.5 meter cable shield look like a pretty efficient antenna.

Brent DeWitt, AB1LF
Milford, MA

-Original Message-
From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] 
Sent: Friday, January 13, 2017 12:19 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

" I suspect this is just equipment originated CM current, that cannot be
cured with a better cable; but needs a better equipment CM design. (Or a
bunch of heavy ferrites)."

I suspect that is the crux of the issue, as it is for many ports on all
kinds of products.


Ralph McDiarmid
Product Compliance
Solar Business
Schneider Electric




-Original Message-
From: ce-test, qualified testing bv - Gert Gremmen
[mailto:g.grem...@cetest.nl]
Sent: Friday, January 13, 2017 1:01 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

Exactly. Nowadays it's easy to filter high speed ports, and in the case of
shielded cable this is even more easy.
One aspect that can be a problem is cable length. USB and HDMI are limited
in length, and in large rooms that can be a problem, needing repeaters, that
can form  a new problem themselves.

About the cable radiating: If the signal arrives correctly at the end in an
approved cable, the cable is not radiating. I mean it's not the mere fact
that data is running that make the cable radiate.  That is why these cable
are approved and characterized. A radiating signal cable (if due to the
signal) has problems with signal transfer also, especially at this data
rates. In the case of HDMI the external screen is not needed to protect the
signal as the data internally is grouped and internally screened (3 or 5
groups).
I suspect this is just equipment originated CM current, that cannot be cured
with a better cable; but needs a better equipment CM design. (Or a bunch of
heavy ferrites).

Regards,

Ing. Gert Gremmen
Approvals manager




+ ce marking of electrical/electronic equipment Independent Consultancy 
+ Services Compliance Testing and Design for CE marking according to
+ EC-directives:
  - Electro Magnetic Compatibility 2014/30/EC
- Electrical Safety 2014/35/EC
- Radio & Telecommunication Terminal Equipment 99/5/EC

Web:    www.cetest.nl  (English) www.ce-test.nl (Dutch) www.cetest.fr (under
construction)
Phone :  +31 10 415 24 26
---
This e-mail and any attachments thereto may contain information that is
confidential and/or protected by intellectual property rights and are
intended for the sole use of the recipient(s) named above. 
Any use of the information contained herein (including, but not limited to,
total or partial reproduction, communication or distribution in any form) by
persons other than the designated
recipient(s) is prohibited. If you have received this e-mail in error,
please notify the sender either by telephone or by e-mail and delete the
material from any computer. 
Thank you for your co-operation.

-Original Message-
From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Friday 13 January 2017 04:27
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

If I am qualifying a device that connects through a cable to this TV, but
not the TV itself, why would it physically have to be part of the set-up in
the test chamber? Why could it not simply be support equipment in an
adjacent chamber, providing the proper interface at the end of the cable?

Ken Javor
Phone: (256) 650-5261


> From: Doug Smith <d...@emcesd.com>
> Reply-To: <d...@emcesd.com>
> Date: Thu, 12 Jan 2017 16:32:06 -0800
> To: <EMC-PSTC@LISTSERV.IEEE.ORG>, Ken Javor 
> <ken.ja...@emccompliance.com>
> Subject: Re: [PSES] lowest emissions 4k TV?
> 
> Hi Ken,
> 
> Unless you are required to include a 4k TV or other device as part of 
> your test setup!
> 
> Doug
> 
> On Thu, 12 Jan 2017 18:20:05 -0600, Ken Javor 
> <ken.ja...@emccompliance.com> wrote:
> Not proffering a solution here, but the amount of traffic on this 
> topic has
>> surprised me. Back in the day when most testing was on an OATS, I 
>> would have understood the concerns expressed, but nowadays most 
>> testing is performed in a SAC simulating an OATS. With the latter it 
>> is si

Re: [PSES] lowest emissions 4k TV?

[Brent DeWitt]

It seems that there is a potential conflict between CISPR 32 and ANSI C63.4
with respect to AE/support equipment.  CISPR 32, as I remember, specifically
says to minimize the emissions from the AE/support equipment while C63.4
does have the support equipment in the test environment.  Ghery Pettit is
more qualified to comment, but I believe there is work going on to reconcile
the two.

Brent DeWitt, AB1LF
Milford, MA

-Original Message-
From: Ken Javor [mailto:ken.ja...@emccompliance.com] 
Sent: Thursday, January 12, 2017 7:20 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

Not proffering a solution here, but the amount of traffic on this topic has
surprised me. Back in the day when most testing was on an OATS, I would have
understood the concerns expressed, but nowadays most testing is performed in
a SAC simulating an OATS. With the latter it is simple to use any
off-the-shelf device in an external chamber just as the appropriate load
interface for the test sample, and provide filtering external to the chamber
necessary to clean up any emissions that could pollute the test chamber
ambient. With a shielded cable, it might be as simple as running it through
a stuffing tube and grounding out the rf current running external to the
shield. Or there could be a high quality shielded cable used in the test
chamber, which connects to a bulkhead-mounted and grounded adapter, and
external to the chamber, the noisy support equipment and any crummy cable
can be used.

Lots of possible variations, but the point is that with a SAC, we don't have
to be near as picky about the support equipment.

Ken Javor
Phone: (256) 650-5261


> From: Ralph McDiarmid <ralph.mcdiar...@schneider-electric.com>
> Reply-To: Ralph McDiarmid <ralph.mcdiar...@schneider-electric.com>
> Date: Thu, 12 Jan 2017 20:59:57 +
> To: <EMC-PSTC@LISTSERV.IEEE.ORG>
> Conversation: [PSES] lowest emissions 4k TV?
> Subject: Re: [PSES] lowest emissions 4k TV?
> 
> I wonder if RF current on the coax coming in to the cable box then
radiates
> from the HDMI cable?   All that overhead cable strung through residential
> neighborhoods must pick up a lot of RFI on its outer braid.
> 
> Ralph McDiarmid
> Product Compliance
> Solar Business
> Schneider Electric
> 
> -
> 
> This message is from the IEEE Product Safety Engineering Society 
> emc-pstc discussion list. To post a message to the list, send your 
> e-mail to <emc-p...@ieee.org>
> 
> All emc-pstc postings are archived and searchable on the web at:
> http://www.ieee-pses.org/emc-pstc.html
> 
> Attachments are not permitted but the IEEE PSES Online Communities 
> site at http://product-compliance.oc.ieee.org/ can be used for 
> graphics (in well-used formats), large files, etc.
> 
> Website:  http://www.ieee-pses.org/
> Instructions:  http://www.ieee-pses.org/list.html (including how to
> unsubscribe)
> List rules: http://www.ieee-pses.org/listrules.html
> 
> For help, send mail to the list administrators:
> Scott Douglas <sdoug...@ieee.org>
> Mike Cantwell <mcantw...@ieee.org>
> 
> For policy questions, send mail to:
> Jim Bacher:  <j.bac...@ieee.org>
> David Heald: <dhe...@gmail.com>

-

This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<emc-p...@ieee.org>

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at
http://product-compliance.oc.ieee.org/ can be used for graphics (in
well-used formats), large files, etc.

Website:  http://www.ieee-pses.org/
Instructions:  http://www.ieee-pses.org/list.html (including how to
unsubscribe) List rules: http://www.ieee-pses.org/listrules.html

For help, send mail to the list administrators:
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Mike Cantwell <mcantw...@ieee.org>

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This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
<emc-p...@ieee.org>

All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html

Attachments are not permitted but the IEEE PSES Online Communities site at 
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

Website: 

Re: [PSES] lowest emissions 4k TV?

[Brent DeWitt]

I don’t want to go name bashing to the whole list, but about a year ago I had 
the project buy a bunch of very expensive HDMI cables in various lengths to 
compare against the cable we designed and have built for us.  This company 
proudly advertised “THX Certified”.  It appears that certification has little 
to do with shielding.  That, or the manufacturer sent THX something very 
different than what they sold me, because they were some of the worst cables 
I’ve ever seen in terms of radiated emission characteristics.  Dissection of 
one showed a ½ inch drain wire as the only shield to shell connection on a 4k 
advertised product.



It ends up that our Bose branded cables are about as good as anything I can 
find.  That’s not a sales pitch because (maybe unfortunately) we don’t sell 
them, only include them with the A4V product.



From: Adam Dixon [mailto:lanterna.viri...@gmail.com]
Sent: Wednesday, January 11, 2017 8:34 AM
To: Brent DeWitt <bdew...@ix.netcom.com>
Cc: EMC-PSTC@listserv.ieee.org
Subject: Re: [PSES] lowest emissions 4k TV?



I added the FCC search option initially based on my first search returning one 
example from a supplier whose North American office is near me in the Atlanta 
area.  I tried a couple other big names and didn't want to sort through 
hundreds of entries, so there was an early morning WalMart trip today to look 
at labels.  The FCC ID portion of current generation smart TV labels now gives 
the WiFi module supplier's ID with "Contains  ID yy" language.  Oh 
well

Also, am interested to know if anyone has comparison data with respect to TV 
size?  From comments thus far and looking at a handful of tear down 
videos/pictures, I wonder how dramatic the differences may be between a 40" and 
a 70".  Integrated speakers and button controls would give a nice range of 
internal cable lengths, as well as the raw panel size and power supply 
differences.  I have seen differences in raw panel grounding schemes.

With your cables and couplers experience, any feedback from the suppliers and 
are they all current HDMI adopters?  It might be worth contacting the Lattice 
Semiconductor ATC for feedback.  You never know if you are working with a part 
number which is different from the initial sample required by the HDMI testing 
policy.  I had one experience in the DisplayPort world where a repeater was not 
certified though the main silicon inside was.



Cheers,

Adam in Atlanta





On Tue, Jan 10, 2017 at 8:13 PM, Brent DeWitt <bdew...@ix.netcom.com 
<mailto:bdew...@ix.netcom.com> > wrote:

Excellent suggestion about the teardown sites!  I hadn’t thought of that.  The 
problem with FCC filings is there really aren’t any.  TVs are verification only 
devices.  There isn’t a reason for them to be posted to the FCC site (wish 
there was).



Good thoughts on the evolution of the display world.



One thing of particular note is the characteristics of 4k (or even 1080p) HDMI. 
 It has four high speed differential pairs (TMDS) that have specified 
transition times between 85 and 45 psec.  It takes only the slightest skew in 
this signal to create significant CM voltage on the system.  I’ve found any 
number of commercially available cables and couplers that blow through the 
emissions limits when used between an otherwise compliant source and sink.



From: Adam Dixon [mailto:lanterna.viri...@gmail.com 
<mailto:lanterna.viri...@gmail.com> ]
Sent: Tuesday, January 10, 2017 7:23 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] lowest emissions 4k TV?



In addition to the recommendations such as James', it may be worth some time 
looking at teardown videos (YouTube, iFixit, etc.) and FCC filings (the 
internal photos entry among all of the documents) to get an idea of 
construction.  You won't know if you get a similarly well-performing sample 
like James' or an out-of-spec dud when you make the purchase 
decision.unless 17 other PSTC members recommend the same make/model. ;-)

Also, maybe a colleague on the list would have insight for the construction of 
medical class 4K displays versus consumer class in the event there are better 
regulatory margins that accompany the grayscale/color rendering performance 
requirements (whether implemented in hardware or firmware).

>From my experience, there has been a shift in the display industry when 
>looking at internal construction where ferrite beads, metal foil tapes, outer 
>metal chassis have disappeared and it's now an LCD panel with its own 
>regulatory behaviors and several PCBs (power supply, TCON, scaler, WiFi, etc.) 
>bolted on the back with a mix of flex and discrete wire harnessesall 
>covered by a rear plastic cover.  Some of the shift is a function of moving 
>from CCFL to LED backlighting, some from having strictly digital I/O and 
>probably a few other factors like better PCB design/layout t

Re: [PSES] lowest emissions 4k TV?

[Brent DeWitt]

Excellent suggestion about the teardown sites!  I hadn’t thought of that.  The 
problem with FCC filings is there really aren’t any.  TVs are verification only 
devices.  There isn’t a reason for them to be posted to the FCC site (wish 
there was).



Good thoughts on the evolution of the display world.



One thing of particular note is the characteristics of 4k (or even 1080p) HDMI. 
 It has four high speed differential pairs (TMDS) that have specified 
transition times between 85 and 45 psec.  It takes only the slightest skew in 
this signal to create significant CM voltage on the system.  I’ve found any 
number of commercially available cables and couplers that blow through the 
emissions limits when used between an otherwise compliant source and sink.



From: Adam Dixon [mailto:lanterna.viri...@gmail.com]
Sent: Tuesday, January 10, 2017 7:23 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?



In addition to the recommendations such as James', it may be worth some time 
looking at teardown videos (YouTube, iFixit, etc.) and FCC filings (the 
internal photos entry among all of the documents) to get an idea of 
construction.  You won't know if you get a similarly well-performing sample 
like James' or an out-of-spec dud when you make the purchase 
decision.unless 17 other PSTC members recommend the same make/model. ;-)

Also, maybe a colleague on the list would have insight for the construction of 
medical class 4K displays versus consumer class in the event there are better 
regulatory margins that accompany the grayscale/color rendering performance 
requirements (whether implemented in hardware or firmware).

>From my experience, there has been a shift in the display industry when 
>looking at internal construction where ferrite beads, metal foil tapes, outer 
>metal chassis have disappeared and it's now an LCD panel with its own 
>regulatory behaviors and several PCBs (power supply, TCON, scaler, WiFi, etc.) 
>bolted on the back with a mix of flex and discrete wire harnessesall 
>covered by a rear plastic cover.  Some of the shift is a function of moving 
>from CCFL to LED backlighting, some from having strictly digital I/O and 
>probably a few other factors like better PCB design/layout to ensure robust 
>high speed I/O performance.

And a last option depending on time/$$ for comparison testing may be to use a 
different display load (projector, HDMI extender, etc.) to understand the 
relative behaviors.



-Adam in Atlanta



On Tue, Jan 10, 2017 at 5:30 AM, Pawson, James <james.paw...@echostar.com 
<mailto:james.paw...@echostar.com> > wrote:

Hi Brent,



I’ve had some success with a (now slightly old) Samsung 4k TV that wasn’t too 
noisy, model UE48JU7000T.



James







From: Brent DeWitt [mailto:bdew...@ix.netcom.com <mailto:bdew...@ix.netcom.com> 
]
Sent: 10 January 2017 01:57
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: [PSES] lowest emissions 4k TV?



Hi group,



Any suggestions on the best available 4k TV for emissions testing support?  We 
seem to be in a continuous churn of looking for good, commercially available, 
sources and sinks.  It would be a real plus if it also had ARC capability!



I’m also wondering if there would be much support for a WIKI site for the EMC 
community to post their findings on support devices.  Nothing proprietary, just 
measurements of “off the shelf” support equipment like TVs, monitors and 
sources.



Thanks all!



Brent DeWitt

Milford, MA




 
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Re: [PSES] lowest emissions 4k TV?

[Brent DeWitt]

Spot on John.  If the support (AE) sources and sinks are only a few dB below 
the limit, they are compliant, but make troubleshooting and evaluating the 
interference generated by our equipment very tedious to sort out.  Maybe I’m 
just lazy, but I’d like to spend my time improving our products rather than 
somebody else’s.



Thanks for the support!

Brent



From: John Woodgate [mailto:jmw1...@btinternet.com]
Sent: Tuesday, January 10, 2017 6:39 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?



The thread is about finding low-emission products (well below relevant limits) 
to act as 'support devices' , aka 'auxiliary equipment'. The low emissions are 
required in order not to significantly affect the measurements of the emissions 
of the equipment under test.



With best wishes DESIGN IT IN! OOO – Own Opinions Only

 <http://www.jmwa.demon.co.uk/> www.jmwa.demon.co.uk J M Woodgate and 
Associates Rayleigh England



Sylvae in aeternum manent.



From: Grasso, Charles [mailto:charles.gra...@echostar.com]
Sent: Tuesday, January 10, 2017 11:24 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] lowest emissions 4k TV?



[ShowerThoughts]
Given the amount of effort that goes into EMC research, design, manufacturing 
etc.. shouldn’t
compliant devices be the norm and not the exception?



[I understand variability and so on … but really …?]



Best Regards

Charles Grasso

Compliance Engineer

Echostar Communications

(w) 303-706-5467

(c) 303-204-2974

(t) 3032042...@vtext.com <mailto:3032042...@vtext.com>

(e) charles.gra...@echostar.com <mailto:charles.gra...@echostar.com>

(e2) chasgra...@gmail.com <mailto:chasgra...@gmail.com>







From: Brent DeWitt [mailto:bdew...@ix.netcom.com]
Sent: Tuesday, January 10, 2017 2:11 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] lowest emissions 4k TV?



I should have mentioned that, in this case, we (Bose Corp.) are the test lab 
and it's our equipment we're testing.  We just came out with a couple of new 
audio-for-video devices that route HDMI through to pick out the 5.1 surround.  
Had a heck of a time finding good sources and sinks.



Not sure there are very many test reports to be looked at since TVs are 
verification only device.  I suppose that more might be found if they 
incorporate non-modular Wi-Fi or RF remotes..



Brent

-Original Message-
From: Jim Bacher
Sent: Jan 10, 2017 8:15 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] lowest emissions 4k TV?

It is ok to post recommendations on devices that are good for testing to this 
list.  As the list is archived one can always search the archives for such 
things.



I have used several approaches to finding good support devices. I have like 
others looked at FCC test reports.  For the most part it was after getting 
recommendations to make sure it was a good choice.  I look to make sure it was 
tested properly and had 6 dB of margin. That allows for production variations. 
I have on rare occasions looked for good support devices on the FCC website.



I have also contacted compliance engineers at the company of interest to see 
what they recommend.  In one case they told me not to use theirs.



Not everyone supplies all support devices needed for testing.  So the test labs 
do have support devices.  Therefore you can ask your test lab as well,  as they 
might have favorite support devices.



Jim

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Re: [PSES] lowest emissions 4k TV?

[Brent DeWitt]

I should have mentioned that, in this case, we (Bose Corp.) are the test lab and it's our equipment we're testing.  We just came out with a couple of new audio-for-video devices that route HDMI through to pick out the 5.1 surround.  Had a heck of a time finding good sources and sinks.Not sure there are very many test reports to be looked at since TVs are verification only device.  I suppose that more might be found if they incorporate non-modular Wi-Fi or RF remotes..Brent-Original Message-
From: Jim Bacher 
Sent: Jan 10, 2017 8:15 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

It is ok to post recommendations on devices that are good for testing to this list.  As the list is archived one can always search the archives for such things. I have used several approaches to finding good support devices. I have like others looked at FCC test reports.  For the most part it was after getting recommendations to make sure it was a good choice.  I look to make sure it was tested properly and had 6 dB of margin. That allows for production variations. I have on rare occasions looked for good support devices on the FCC website. I have also contacted compliance engineers at the company of interest to see what they recommend.  In one case they told me not to use theirs. Not everyone supplies all support devices needed for testing.  So the test labs do have support devices.  Therefore you can ask your test lab as well,  as they might have favorite support devices. Jim
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[PSES] lowest emissions 4k TV?

[Brent DeWitt]

Hi group,

 

Any suggestions on the best available 4k TV for emissions testing support?
We seem to be in a continuous churn of looking for good, commercially
available, sources and sinks.  It would be a real plus if it also had ARC
capability!

 

I'm also wondering if there would be much support for a WIKI site for the
EMC community to post their findings on support devices.  Nothing
proprietary, just measurements of "off the shelf" support equipment like
TVs, monitors and sources.

 

Thanks all!

 

Brent DeWitt

Milford, MA



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Re: [PSES] EN 300 328 - Bluetooth testing

[Brent DeWitt]

The two things I've found to be problematic are band edge and spurious emissions.  So many of the other characteristics are cast in silicon that they've alreeady been worked out.Brent-Original Message-
From: Jim Bacher 
Sent: Jan 9, 2017 9:04 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] EN 300 328 - Bluetooth testing

I have only tested modules produced by others,  however I have never had a failure. The biggest issue has been getting the software to properly control the device so it could be tested easily. On Jan 9, 2017 3:41 AM, "Amund Westin"  wrote:To you guys who have deep experience with Bluetooth test and approvals according to EN 300 328, are there any of the required tests that is really hard to fulfil and often fails during tests, and therefore should have special attention during the development phase?

... or requirements that often lead to discussions because it can have several interpretations 


Thanks for all feedbacks!


EN 300 328 requirements:
-RF output power
-Power Spectral Density
-Duty Cycle, Tx-sequence, Tx-gap
-Accumulated Transmit time,Frequency Occupation & Hopping Sequence
-Hopping Frequency Separation
-Medium Utilization (MU) factor
-Adaptivity
-Occupied Channel Bandwidth
-Transmitter unwanted emissions in the out-of-band domain
-Transmitter unwanted emissions in the spurious domain
-Receiver spurious emissions
-Receiver Blocking
-Geo-location capability



Best regards
Amund

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Re: [PSES] Practical ethics? -- text version

[Brent DeWitt]

Well said Cortland, my old friend.  I also wish to compliment John Allen on his 
ethical stance.  In my 40+ years of EMC, I have few experiences with the 
military side of things, so cannot comment, but I am encouraged by your 
willingness to speak out.  Our field of endeavor is based on metrology and 
integrity.  May we all do our best.

Brent DeWitt

-Original Message-
From: Cortland Richmond [mailto:k...@earthlink.net] 
Sent: Tuesday, December 27, 2016 1:52 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Practical ethics? -- text version

On 12/27/2016 10:39 AM, John Allen wrote:
> in the wider context, this sort of thing can place a great strain on 
> the ethics of the  guy in the middle  who understands what actually 
> needs to be done and  speaks his mind ,

Here we come to the crux of the matter. It is an organization's corporate 
culture that determines how ethical it will be, and it's all too common that 
organizations don't give a hoot about ethics.

When convenience, economy, speed and the next promotion become more important 
than quality, shortcuts become more common than preparing for the work,

 and small lapses of ethical practice may be excused with "we can make up for 
it later" -- leading to worse ones.

At one time, statistical quality control tests were required in EMC -- my first 
job was doing this for TEMPEST, VDE 0871 and FCC Part 15 -- and this not only 
finds things gone wrong, it can led to interesting telephone calls such as a 
Chinese factory manager screaming at me around midnight his time, "How come you 
shut down my factory?!?"  That one wasn't TEMPEST -- but I've a couple of 
stories about that too. There's a what, 50 years? timeline before I can tell 
'em, and it won't be up for quite a while.

In general, no one wants to pay up front to avoid problems later -- but I've 
seen the frenzy  that can result from that approach.

So, on a larger stage, has the world, after just one person wanting to save 
$100 a day ended up costing maybe $100 MILLION over the long term.

Whoops.

https://www.rt.com/usa/332225-flint-water-crisis-failures-interview/


Cortland Richmond

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Re: [PSES] Public view of this email server?

[Brent DeWitt]

Many companies use the legal term of “at will” employment.  It pretty much 
gives an employer the right to dismiss without disclosing any motivation.



From: Ted Eckert [mailto:07cf6ebeab9d-dmarc-requ...@ieee.org]
Sent: Tuesday, November 22, 2016 11:49 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Public view of this email server?



In the United States, the First Amendment prevents governments from regulating 
speech. However, employment at a specified company is not a constitutionally 
protected right. A private company is permitted to fire you for something you 
say. Many people learn in the United States have learned this the hard way. 
Employment law is normally governed at the state level. In many states, your 
employer can fire you without giving any reason at all. If they don’t like what 
you said, they don’t have to state that as a reason for termination. Employers 
in the U.S. can’t fire you based on race, gender and a few other aspects, but 
speech is generally allowed to be restricted as a condition of employment.



Ted Eckert

The opinions expressed are my own and do not necessarily reflect those of my 
employer.



From: John Woodgate [mailto:jmw1...@btinternet.com]
Sent: Tuesday, November 22, 2016 8:03 PM
To: Ted Eckert  >; 
EMC-PSTC@LISTSERV.IEEE.ORG 
Subject: RE: [PSES] Public view of this email server?



An employer seeking to restrict  personal communication on the Internet  may 
violate the First Amendment..



To replace the sesquipedalian disclaimers imposed by corporate lawyers, I 
coined the TLA OOO which has appeared in my sig-tag since time immemorial.



With best wishes DESIGN IT IN! OOO – Own Opinions Only

  www.jmwa.demon.co.uk J M Woodgate and 
Associates Rayleigh England



Sylvae in aeternum manent.



From: Ted Eckert [mailto:07cf6ebeab9d-dmarc-requ...@ieee.org]
Sent: Wednesday, November 23, 2016 3:06 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG 
Subject: Re: [PSES] Public view of this email server?



I work in an environment where it is reasonable for me to assume that anything 
I write may be accessed by a plaintiff during the discovery process of some 
future lawsuit. It makes me more careful what I say, but it generally doesn’t 
prevent me from responding to a forum such as this. The disclaimer I use is 
based on guidance given by my current employer and is similar to what has been 
required at past employment when responding publically. I can say what I want 
as long as I indicate that it is a personal response and not necessarily the 
opinion of my employer. Despite the environment, my employer does not prohibit 
open communication on public forums. The employees are encouraged to speak 
responsibly and recognize that they may be seen as representatives of Microsoft.

-


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Re: [PSES] Measurement Uncertainty Above 18 GHz

[Brent DeWitt]

I agree with Dennis.  Any measurement of anything has uncertainty.  The 
applicable question is; can we agree on a uniform method of evaluation of that 
uncertainty.  Many of the procedures and methods we use in the EMC world are 
not perfect, but if we strive to make them as uniform as possible, we may have 
common ground for agreement with respect to the results.



Standard disclaimers for personal opinion apply!



Brent Dewitt, AB1LF

Milford, MA



From: dward [mailto:dw...@pctestlab.com]
Sent: Sunday, October 30, 2016 1:46 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Measurement Uncertainty Above 18 GHz



All measurements are subject to uncertainty. Because there is no “standard” for 
sites above a specific frequency does not mean that measurements are not 
‘uncertain’. It just means we may not know them in relation to a specific 
standard.  So, while measurement is always “uncertain”, it is basically more 
uncertain simply because we have no established gage to judge them by (yet).





​

Dennis Ward

This communication and its attachements contain information from PCTEST 
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From: John Woodgate [mailto:jmw1...@btinternet.com]
Sent: Saturday, October 29, 2016 9:16 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] Measurement Uncertainty Above 18 GHz



I don't see that one can tell if it's reasonable or not without a lot more 
information, which is probably confidential to your company.



But there isn't any major effect that occurs just above 18 GHz to make CISPR 
16-4-2 no longer a good guide at least. Of course, you need an FAR that has no 
unacceptable defects at the frequency you are using, and if that is far above 
18 GHz, effects such as atmospheric absorption need to be considered.



With best wishes DESIGN IT IN! OOO – Own Opinions Only

 <http://www.jmwa.demon.co.uk/> www.jmwa.demon.co.uk J M Woodgate and 
Associates Rayleigh England



Sylvae in aeternum manent.



From: Grace Lin [mailto:graceli...@gmail.com]
Sent: Saturday, October 29, 2016 4:47 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG <mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: [PSES] Measurement Uncertainty Above 18 GHz



Dear Members,



Is it reasonable to request measurement uncertainty (MU) above 18 GHz?  CISPR 
16-4-2 Edition 2.1 seems only up to 18 GHz.



Is there any standard that addresses MU above 18 GHz?



Is it reasonable to claim that MU is not applicable for radiated disturbance / 
emission measurement above 18 GHz as there is no site validation standard 
available for frequency above 18 GHz?



Thank you very much and I look forward to hearing from you.



Best regards,

Grace Lin

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[PSES] HDMI questions

[Brent DeWitt]

I’ve been working with some Silicon Images (Lattice Semi) 9777 multiplexer 
chips lately and would appreciate any insight list members might have.  When 
used at any resolution below 4k, there seems to be a 10 dB emission “pedestal” 
that stands out of the baseline emission at several frequencies, 742 MHz in 
particular.  The pedestal is 666 usec long and repeats at whatever frame rate 
is selected.  At first, I thought it was correlated with the SPI bus activity, 
since the timing was identical, but further experiments show that not to be 
true.



My question is, is this inherent to HDMI, or to the 9777?  As is probably 
obvious, I don’t have a whole lot of experience with HDMI video.



Thanks all!



Brent DeWitt, AB1LF

Milford, MA



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Re: [PSES] Antenna gain measurement standard

[Brent DeWitt]

I forgot to say that, depending on the frequency (higher is worse) it’s almost 
impossible to know what the maximum antenna gain you will find in a full 
spherical is versus three orthogonal cuts.  In my products I’ve seen 7dB 
difference at 5 GHz of an antenna in a product.



It’s also worth noting that there are _very_ few submittals I’ve seen that 
include spherical pattern data.  The three axis palanr measurements are much 
more common.



Sorry for the list pollution of two posts back to back!



Brent DeWit



From: Stephen Whalen [mailto:scwha...@bellsouth.net]
Sent: Friday, July 01, 2016 11:01 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Antenna gain measurement standard



Greetings,

Does anyone know which standard is used for measuring antenna gain?

Are 3D antenna gain measurements typically different than 2D with regards to 
peak gain?  If so, what's typical delta, 0.5dB or less?



Regards,

Stephen

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Re: [PSES] Antenna gain measurement standard

[Brent DeWitt]

Hi Stephen,



Lots of questions are required to answer your question with any accuracy.  I 
assembled a system to do spherical patterning to our product antennas above 1 
GHz, so I have some exposure to the problems.



A few of those questions:

-  Are these product antennas rather than well behaved metrology type 
antennas?

-  Are they independent or built into a product?

-  Is the transmitting device unique or intended to be used as a module 
in many products?

-  What is the frequency range to be investigated?



If I can make a guess, my interpretation of 2D would be planar pattern cuts on 
each of three orthogonal axes vs 3D being an altitude/azimuth pattern measured 
at some spherical radius.



Just to be even less helpful than I have been, there are IEEE, ANSI and IEC 
standards that don’t always agree and need more information to pick and choose 
from.



Keep at it!



Brent G DeWitt

Milford, MA



From: Stephen Whalen [mailto:scwha...@bellsouth.net]
Sent: Friday, July 01, 2016 11:01 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Antenna gain measurement standard



Greetings,

Does anyone know which standard is used for measuring antenna gain?

Are 3D antenna gain measurements typically different than 2D with regards to 
peak gain?  If so, what's typical delta, 0.5dB or less?



Regards,

Stephen

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Re: [PSES] AMA Warns of Harm from LED Streetlights’ Blue Light

[Brent DeWitt]

Just came back from Morocco in May and didn’t see any amber headlamps.  Maybe 
times have changed.



Brent G DeWitt
Senior EMC Design Engineer

Bose Corporation

The Mountain Rd, MS 450

Framingham, MA 01701

508-766-1494



From: Doug Powell [mailto:doug...@gmail.com]
Sent: Wednesday, June 22, 2016 3:18 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] AMA Warns of Harm from LED Streetlights’ Blue Light



John,

​​

I have to wonder about the "blue rich" automotive headlights, for me they are a 
strong irritant and very distracting.  Amazingly, I actually heard some people 
say the blue are better because you can see further at night and in fog.



Years ago I once heard that in Morocco, the preferred color for car headlamps 
is amber.  Never did verify if that was true.



-Doug





Douglas E Powell

Laporte, Colorado USA

  doug...@gmail.com

  http://www.linkedin.com/in/dougp01







On Wed, Jun 22, 2016 at 11:08 AM, John Allen  > wrote:

Just had a routine info email from the ECM Web highlighting an interesting 
American Medical Association (AMA) article on the potential harmful effects of 
LED streetlights - see here:

http://electricalmarketing.com/blog/ama-warns-harm-led-streetlights-blue-light?NL=ECM-07
 

 
=ECM-07_20160622_ECM-07_825=42=article_1_b_rid=CPG0400025478_campaign=8880_medium=email=0cf944f7f4f14ecbb045b2dbb57fc4de

I wonder what the effects could be in the future – and if anyone else, 
anywhere, has already picked up/investigated this subject?


John E Allen

W.London, UK

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http://www.linkedin.com/in/dougp01

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Re: [PSES] Pre-Amp mounted to antenna

[Brent DeWitt]

Not exactly "turn key", but Mini-Circuits will sell you connectorized bias
Ts and DC blocks that will get the job done.

 

Hope that helps,

Brent DeWitt

Milford, MA

 

 

From: Kunde, Brian [mailto:brian_ku...@lecotc.com] 
Sent: Tuesday, March 15, 2016 1:27 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Pre-Amp mounted to antenna

 

Greetings. 

 

I'm looking for a low noise Pre-Amp for Radiated Emissions 30Mhz to 1Ghz (or
higher) with a gain of 20-30dB; but here's the catch. I want it to mount
directly to the "N" connector on my BiLog Antenna and be powered by a
downstream Power Supply box that sends DC down the coax. Just like how TV
Antenna pre-amps work.

 

Does anyone know of a turn-key over the counter product like this that is
available?

 

I know such a design can have great benefits and be plagued with troubles
such as reflections so I know it has to be done right and done well.  

 

Any information would be most helpful.

 

Thanks in advance.

 

The Other Brian

 

 

  _  


LECO Corporation Notice: This communication may contain confidential
information intended for the named recipient(s) only. If you received this
by mistake, please destroy it and notify us of the error. Thank you. 


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Re: [PSES] Source for Quality Video Cables

[Brent DeWitt]

There has been a recent marketing blitz for "certified" HDMI cables.  THX has 
started a certification program and Kordz is one company that proudly 
advertises _very_ expensive cables for high video resolutions.  I haven't 
looked at the SI characteristics, but the standard clearly doesn't address EMC 
concerns and the performance of the cables in radiated emission shows it.  YMMV

Brent DeWitt
Milford, MA

-Original Message-
From: Kunde, Brian [mailto:brian_ku...@lecotc.com] 
Sent: Wednesday, March 02, 2016 4:56 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Source for Quality Video Cables

A quick trip in the "Way Back" machine brings me back to the early PC days. To 
get parallel printers to pass the FCC class B requirements we had to use a very 
expensive cable purchased directly from IBM which had double shielded cable and 
heavy metal back shells. The cost was something like $50 which was a lot of 
money for a cable.

However, you could go to the local electronic store at the time and buy a 
printer cable made up of ribbon cable with crimp on D-sub on one end and a 
Centronics connector on the other for like $5. I think the only people who 
bought the $50 cable was EMC labs.

The Other Brian

-Original Message-
From: Cortland Richmond [mailto:k...@earthlink.net]
Sent: Wednesday, March 02, 2016 4:11 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Source for Quality Video Cables

On 3/2/2016 11:54 AM, IBM Ken wrote:
> perhaps you could enclose the whole cable in a tubular copper braid 
> (or mylar-foil tape) and try to solder to the shield of the DVI 
> connectors

Around 1987, my late brother, who was a free-lance C-language consultant, 
bought an extremely high resolution 27 inch, black-and-white (okay, orange and 
white) monitor. That way he could see several pages of code at the same time.

Unfortunately, it interfered with the television reception of another resident 
on the 18th floor. I was working in EMC at the time, and took my ICOM R 7000 
receiver over with an inductive probe.  The noise was coming from the video 
cable.

I did precisely what Ken suggests; I took a few feet of the shield from a piece 
of RG-8 cable slit down the side, slid it over the cable, made sure the braid 
overlapped across the slit and wrapped it tightly in electrical tape. Then I 
used tie-wraps to ensure the shield made good contact to the EMC back shells on 
the connectors. Problem solved!

 From the "For What It's Worth Department": I think modern monitors are 
quieter.  It was a *BIG* CRT   and Class A to boot.

Cortland Richmond

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Re: [PSES] Spectrum analyzer and noise floor

[Brent DeWitt]

Generally pretty correct Ralph.  The only "picky" point I would have is
about #2.  The pre-amp really doesn't lower the noise floor created by #1.
It raises the signal level further above it.

 

Best of luck,

 

Brent DeWitt

Bose Corporation

Framingham, MA

 

From: McDiarmid, Ralph [mailto:ralph.mcdiar...@schneider-electric.com] 
Sent: Tuesday, February 23, 2016 7:43 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Spectrum analyzer and noise floor

 

I would like to explain to a colleague why the noise floor on a SA does not
look flat as it sweeps across a given frequency range after antenna factors,
cable factors, external gain and external attenuation are programmed into
its display function.   

I think it breaks down to these fundamental points: 

1. the SA receiver has noise in its attenuator, mixer and filter circuits
(say -80 dBm, and maybe flat within a limited  frequency range) 
2. the external amplifier has some noise too, but its gain lowers the noise
floor created by #1  (also flat within a limited frequency range) 
3. the cables have losses which are frequency dependant, and those can be
entered as loss factors into the SA  (shapes the noise floor a little and
those losses raise the noise floor) 
4. the antenna has a gain which is frequency dependant with several dB of
hills and valleys across its usable frequency range (that really shapes the
noise floor more than 1, 2 or 3 above) 
5. noise floor shape caused by #4 is the mirror image of the antenna factor
vs frequency 

Is that a decent summary? 
. 


Ralph McDiarmid
Compliance Engineering
Residential/Commercial
Solar Business
Schneider Electric 

D  +1 (604) 422 2622 x62622
E   <mailto:ralph.mcdiar...@schneider-electric.com>
ralph.mcdiar...@schneider-electric.com 

3700 Gilmore Way
Burnaby
BC
Canada

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[PSES] 4k TV/monitor?

[Brent DeWitt]

Does anyone have a recommendation for a 4k capable tv or monitor to use for emissions testing?  I have a couple of samples of Samsung U28E590D which pass radiated emissions above a GHz, but not by much (3dB).Any positive experiences would be welcomed!Brent DeWitt
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Re: [PSES] Stricter limits than legal (CISPR11, IEC, etc,) Where?

[Brent DeWitt]

Nobody seems to be asking _why_ margin is important or not.  I expect no one 
believes airliners are going to fall out of the sky or grandma’s pacemaker to 
stop if a product is 10 dB over the FCC/CISPR Class B limits for radiated 
emissions.  So why?  For emissions (not immunity, that’s a different question) 
it’s probably so you can be guaranteed of legally selling the product in the 
light of a third party audit or an internal whistle blower (just kidding).  So 
now the _probabilities_ start stacking up and your tolerance for risk comes 
into play.  All of the factors brought up by this list are valid for one 
product scenario or another.  Simply put, if you take the maximum measurement 
uncertainty allowed for a lab under the law, multiply it by 1.414, add the 
observed statistical variation of a large enough sample of your product that 
the standard deviation from all causes starts settling down, and use that as 
your required margin you should have a guaranteed peaceful sleep.  The bad news 
is that nobody really wants to design for a number that huge (or should they?).

 

All that is a long winded way of saying “there is no universal right answer”.  
Examine _your_ product, _your_ lab and _your_ anxiety level and act accordingly.

 

Respectfully,

 

Brent G DeWitt, AB1LF

Happily employed in the EMC thing since 1978

 

 

From: Douglas Powell [mailto:doug...@gmail.com] 
Sent: Monday, October 12, 2015 7:23 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Stricter limits than legal (CISPR11, IEC, etc,) Where?

 

Patrick,

 

In your story, what you did was a small statistical study. Multiple samples 
allow you to do this. It is similar to the problems of EMC. One possibility is 
to test  multiple units and record the results as a probability or simply 
record the worst case. When dealing with large expensive equipment that can 
take days to evaluate, it is far simpler to build confidence by simply adding, 
pause for effect, margin.  

 

Doug

 

‎Douglas E Powell

 

doug...@gmail.com  

http://www.linkedin.com/in/dougp01

 

 

 


From: Patrick

Sent: Monday, October 12, 2015 5:13 PM

To: doug...@gmail.com  

Cc: EMC-PSTC@listserv.ieee.org  

Subject: Re: [PSES] Stricter limits than legal (CISPR11, IEC, etc,) Where?

 

Ahhh, our old friend: "Margin".

Margin is one of those timeless EMC topics.  

 

IMHO- there is simply no evidence that margin is helpful.

 

In a practical sense we all know that a "single-measurement-plus-margin" is not 
a confidence builder.

As an example, think about the last time you worked on your home wiring.

How many times did you read that multi-meter before you touched the wires?  

Did you read it just once?  Then add some margin?

 

Nope- I'll bet you did like me:  I read that meter, and double-read it.  

Then I read it again.

One measurement is simply not enough to build confidence.

 

Next time someone asks you for "reasonable margin" ask them about their last 
wiring project  

 

-Patrick

OOO.  

 

 

On Mon, Oct 12, 2015 at 2:54 PM, Douglas Powell  > wrote:

Ted,

 

Very good points. If minimum passing margins are a result of ‎edge rates on 
transistors, diodes or ICs, then a second source or "upgrade" to a faster 
device can be counterproductive with regard to the emissions profile.  

 

If such engineering changes or supplier changes have occurred, then a retest is 
often the best policy. I was also aware that several cumulative engineering 
changes over time can result in a non-compliance.‎Each change, when 
evaluated by itself was inconsequential. But in aggregate, result was a 
failure. This is often the reason I would require a retest after some number of 
engineering changes had been applied to a product.  Of course, keeping full 
data test reports on each passing result is really the only way to do this 
well.  

 

Doug

 

Douglas E Powell

 

doug...@gmail.com  

http://www.linkedin.com/in/dougp01

 


From: Ted Eckert

Sent: Monday, October 12, 2015 2:44 PM

To: EMC-PSTC@LISTSERV.IEEE.ORG  

Reply To: Ted Eckert

Subject: Re: [PSES] Stricter limits than legal (CISPR11, IEC, etc,) Where?

 

In addition to the responses from Doug, Ghery and Brian, I will note that 
margin protects you from unexpected or unknown changes from component 
suppliers. To some extent, this falls under the manufacturing variance Doug 
mentioned, but component changes is just another area that can be hard to 
control.

 

I’ve had IC vendors do a die shrink on a part resulting in sharper edge rates 
on the outputs. At a previous employer, I was running emissions testing on a 
number of samples where Motorola did a die shrink on the microcontroller we 
were using. Some of my test samples had the old part and some had the new. It 
took a long time to figure out 

Re: [PSES] Best design practices to keep CM currents off a USB 2/3 cable given an unshielded enclosure?

[Brent DeWitt]

Interesting question and of interest to many of us Ken.  My thoughts:

 

-  A choke between board ground and the shield isn't really
desirable.  All it does is create a frequency dependent floating shield.  It
becomes another high Q resonant element in the radiation system driven by
any common mode currents on the contained conductors.  If it were a perfect
shield/conductor and many skin depths thick, that might help by keeping
circulating currents entirely on the inside surface of the shield, but in
reality, they will probably make it to the outside surface and you've got a
pretty efficient antenna.

-  Thinking about "common mode current"; Mr. Kirchoff was right. The
CM noise currents have to come from somewhere _and_ make it back to there.
How?  Displacement currents from the simple capacitance of the EUT to our
earth reference plane are very real, but in many cases, the other
connections, such as the power cable or other signal cables are more
significant.  These currents are, in turn, created by a common mode voltage
driving a poorly defined impedance, so to reduce the radiating current we
have some knobs we _may_ be able to turn:

o   Reduce the common mode drive voltage

*  Reduce timing skew in the USB differential signals caused by simple
propagation delay.

*  Reduce capacitive imbalance on the differential signal (never use
discreet capacitors from each side to ground).

*  Improve driver bypassing to reduce package derived CM current.

o   Increase the loop impedance

*  Add common mode impedance (choke) to the driven pair.

*  Figure out how to increase the isolation of the "other side" of the
radiator from the USB driver through layout or supply (not ground) chokes.

o   Lastly, try to give the currents an easier what to complete their
journey.  No general leads here, but generally layout dependent.

 

I'm sure I'm preaching to the choir on most of this, but you did ask. ;-}

 

Best regards,

 

Brent DeWitt

 

 

 

 

From: Ken Wyatt [mailto:k...@emc-seminars.com] 
Sent: Thursday, September 10, 2015 3:03 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Best design practices to keep CM currents off a USB 2/3
cable given an unshielded enclosure?

 

Hi All,

 

It seems I'm always running into client products with USB 2.0 (or 3.0)
connectors mounted on circuit boards that are enclosed within unshielded
cases. I understand that CM chokes can be added to the data lines. However,
given a circuit board with common-mode noise running all around, these CM
noise currents can couple directly to the connector shield and thence out
along the attached USB cable, creating EMI.

 

Typically, the USB connector shield is soldered directly to the digital
return plane. Is isolating the connector ground from the digital return
plane and inserting a ferrite bead between the two the answer?  Let's assume
a large ferrite choke around the cable is not an option. Any other thoughts
as to what can be done at the board-level to reduce common-mode currents
from getting on the cable shield?

 

I've already done a literature search and found nothing helpful.

 

Thanks so much!

 

Ken


___

 

I'm here to help you succeed! Feel free to call or email with any questions
related to EMC or EMI troubleshooting - at no obligation. I'm always happy
to help!


Kenneth Wyatt
Wyatt Technical Services LLC

56 Aspen Dr.
Woodland Park, CO 80863


Phone: (719) 310-5418


Email Me! <mailto:k...@emc-seminars.com>  | Web Site
<http://www.emc-seminars.com>  | Blog <http://design-4-emc.com/> 

The EMC Blog (EDN) <http://www.edn.com/blog/The-EMC-Blog> 
Subscribe to Newsletter
<http://www.emc-seminars.com/Newsletter/Newsletter.html> 
Connect with me on LinkedIn <http://www.linkedin.com/in/kennethwyatt> 

 

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-

[PSES] HDMI extension cable recommendation?

[Brent DeWitt]

I’m looking for a good quality HDMI extension cable for test use.  Price is not 
an issue since I only need a few.  Does anyone have any recommendations based 
on their shielding and build quality?

Thanks!

Brent DeWitt
Senior EMC Engineer
Bose Corporation

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Re: [PSES] Calculating Reflection Angles on OATS/SAC

[Brent DeWitt]

Hi James,

 

The image concept again is useful.  By definition, the  ground reference
plane is at zero potential.  For that to be true, charges on the real
antenna and its image must be equal and opposite.  Put a plus on one end of
a dipole and a minus on the other and look at them.  If they are vertical,
and the bottom of the real dipole has the minus sign, the top of the image
must be plus for the charges to cancel.  For the horizontal example, if the
left end is plus the same end of the image must be minus for the same
reason.

 

In the extreme thought experiment, if you lowered the vertical dipole so its
center point were at the ground plane (now a monopole), its image would
complete the dipole.  The same extreme applied to the horizontal dipole
would have the two cancelling each other out entirely.  We can see this in
reality, since the vertical polarization with the antenna at one meter
height is usually the strongest emission at low frequencies where the path
length in wavelengths is small.  The first maximum from the horizontal
dipole occurs when there is a 180 degree path length difference between the
real antenna and its image.

 

Does that help any?

Brent

 

From: Pawson, James [mailto:james.paw...@echostar.com] 
Sent: Thursday, August 06, 2015 5:13 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Calculating Reflection Angles on OATS/SAC

 

Many thanks for all of the replies on this topic. The conceptual key I
lacked was the “image” of the receiver below the ground plane which made the
calculations a lot simpler and I’ve now got an up and running spreadsheet.
I’ve also been introduced to things like cotangents and arctangents which
are new to me.

 

The only thing I still remain confused about is the phase of the reflection
from the ground plane.

 

 Gert wrote: “Note that vertical waves invert in polarity on reflection
with the ground plane, where horizontal polarized waves do not.”

 

 Brent wrote: “…and take the difference for phase, remembering that the
horizontally polarized image is 180 degrees out of phase to start with while
the vertical image is in phase.”

 

I might be misunderstanding but these statements seem to contradict each
other. I can kind of see how a vertically polarised wave would be reflected
inverted. If this was the case, could this be compensated for by subtracting
180° from the reflected ground ray to ensure the phases added/subtracted
correctly at the RX antenna?

 

Thanks again

James

 

 

 

_
From: Pawson, James 
Sent: 31 July 2015 15:59
To: EMC-PSTC@LISTSERV.IEEE.ORG mailto:EMC-PSTC@LISTSERV.IEEE.ORG 
Subject: Calculating Reflection Angles on OATS/SAC

 

 

Hi,

 

I’m trying to calculate the distances/angles at which a maximum (in phase)
or minimum (anti-phase) signal would occur on an OATS/SAC.

 

I can do this simply when the TX and RX antennae are the same height above
the reflecting surface as the point of reflection lies halfway between the
two antennae, Distance_tx = Distance_rx. The direct and reflected paths can
be calculated using simple geometry and the wavelength is given by lambda =
c / f.

 

However when the height of the RX antenna is different to the height of the
TX antenna then the horizontal distance to the reflection point is no longer
equidistant. I can see that the ratio Height_tx / Distance_tx = Height_rx /
Distance_rx remains the same because the angle of reflection is the same.
But I’m left with two unknown Distance terms in the equation.

 

Is there a standard equation for calculating the reflection angle on an
OATS/SAC with a varying height antenna? Or can someone give me some pointers
to help me figure it out myself? I was so distracted thinking about this
that I missed my turnoff whilst cycling home the other day.

 

I’ve tried Googling but maybe I’m not putting in the right search term.

 

Any assistance gratefully received.

Thanks and regards,

James

 

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Re: [PSES] Calculating Reflection Angles on OATS/SAC

[Brent DeWitt]

I haven't followed this thread completely, so this has probably already been
said:

The easiest was for me to think of the problem is with image theory.  The
source antenna has an image as far below the ground plane as it is above
the ground plane.  Solve for the hypotenuse of both triangles and take the
difference for phase, remembering that the horizontally polarized image is
180 degrees out of phase to start with while the vertical image is in phase.
For an approximation, use Friis equation to get the amplitude of each path
and add them up.  I say approximation because it assumes far field
propagation, which may not be the case depending on the range and frequency.

Hope that helps,

Brent DeWitt, AB1LF
Milford, MA

-Original Message-
From: CR [mailto:k...@earthlink.net] 
Sent: Saturday, August 01, 2015 8:01 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Calculating Reflection Angles on OATS/SAC

On 7/31/2015 10:59 AM, Pawson, James wrote:
 I can do this simply when the TX and RX antennae are the same height 
 above the reflecting surface as the point of reflection lies halfway 
 between the two antennae, Distance_tx = Distance_rx. The direct and 
 reflected paths can be calculated using simple geometry and the 
 wavelength is given by lambda = c / f.
 However when the height of the RX antenna is different to the height 
 of the TX antenna then the horizontal distance to the reflection point 
 is no longer equidistant. I can see that the ratio Height_tx / 
 Distance_tx = Height_rx / Distance_rx remains the same because the 
 angle of reflection is the same. But I'm left with two unknown 
 Distance terms in the equation.

-

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Re: [PSES] air activated finger probes

[Brent DeWitt]

Look at the Lego Technic line. In the past they had a number of kits with plastic pnuematics. I've used them in the past to build remote button pushers.-Brent-Original Message-
From: Ted Eckert 
Sent: Nov 4, 2014 11:24 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] air activated finger probes














Pneumatic systems may be harder to find than electric systems. However, there are a few construction toys that use simple DC motors that shouldn’t cause significant interference with
 test results. Lego has a number of options with the Mindstorms system being the top of the line. It includes programmable controllers that will give you lots of options, but the controllers may cause interference with test results.

Another option is K’Nex. The construction is a bit easier than Lego, although there aren’t programmable controls. However, I have seen “mouse movers” built out of K’Nex. The device was built to constantly move
 a computer mouse around on a surface for radiated immunity testing. It wouldn’t be too hard to add a rod with cams that actuated the buttons on the mouse. A K’Nex system for a keyboard may be more of a challenge.
http://www.knex.com/


Ted Eckert
Compliance Engineer
Microsoft Corporation
ted.eck...@microsoft.com

The opinions expressed are my own and do not necessarily reflect those of my employer.




From: Sundstrom, Mike [mailto:mike.sundst...@garmin.com]

Sent: Tuesday, November 4, 2014 7:54 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] air activated finger probes



Lego’s

www.lego.com

While at a previous job I had a fellow engineer who became the Lego Engineer. His main job was to support the reliability team do one off jobs like
 what you’re talking about.


Michael Sundstrom
Garmin Compliance Engineer
2-2606
(913) 440-1540

It's not what you look at that matters, it's what you see.
Henry David Thoreau




From: Julian Jones [mailto:ju...@hursley-emc.co.uk]

Sent: Tuesday, November 04, 2014 9:36 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] air activated finger probes



I am looking to make up a simple pneumatic system to press a couple of keys on a keyboard and move a mouse.

Has anyone made up such a kit ?

Some years ago I looked at this and there seemed to be lots around, now searching on Google I can’t find any, or my search parameters are wrong.

Any input gratefully received.

Rgds

Julian




Julian Jones
Hursley EMC Services
Tel: 023 8027 
ddi: 023 8024 0851
Mob: 07787 523 607
julian.jo...@hursley-emc.co.uk
Trafalgar House, Trafalgar Close, ChandlersFord
EASTLEIGH, Hampshire, SO53 4BW
Company Registration 3301279

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Re: [PSES] Human fingertip capacitance.

[Brent DeWitt]

Maybe this is overly simplistic, but there are a zillion (trust me, I'm an
engineer), capacitive touch pad styli out there to choose from.  Since they
clearly simulate a human finger in real operation, why not just include
one or more of them in your test fixture  design?  Of course you still need
a few hundred pF from the body of the stylus to ground to simulate a big
human body full of salt water, but mechanical design is vastly simplified.
This one works well and has replaceable tips for when things wear out:

http://musemee.com/us/index.php

Respectfully,
Brent DeWitt
Milford, MA

-Original Message-
From: Sundstrom, Mike [mailto:mike.sundst...@garmin.com] 
Sent: Thursday, October 09, 2014 3:02 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Human fingertip capacitance.

In a long ago job I learned the two 480K Ohm resistors in the ESD gun ground
lead was to simulate the human body (whole body). Something about shaping
the current pulse or flow to ground?



Michael Sundstrom
Garmin Compliance Engineer
2-2606
(913) 440-1540

It's not what you look at that matters, it's what you see.
Henry David Thoreau

-Original Message-
From: Brian Oconnell [mailto:oconne...@tamuracorp.com]
Sent: Thursday, October 09, 2014 11:41 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Human fingertip capacitance.

Do not believe that it is the 'capacitance' of the human appendage per se,
but the interference with the screen's field. Suspect that the Emperor's
search engine would reveal much more, but an ap note used in a past project
is here:

www.ti.com/lit/an/slaa363a/slaa363a.pdf

Brian

From: Gary McInturff [mailto:gary.mcintu...@esterline.com]
Sent: Thursday, October 09, 2014 9:14 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Human fingertip capacitance.

Trying to set up a jig to test some capacitive touch-panels. It's an
automated probe that disturbs the capacitive field of the sensor - but I'm
clueless what kind of value to shoot for. I thought about the ESD gun
capacitance but I don't know if that actually matches a human fingertip - or
it's the whole body, or that the capacitance of the body of the ESD gun
itself is used to calibrate to some human figure tip capacitance.

I've got some research to do but does anybody have a starting point and a
reference for the capacitance of an average human fingertip. I have the EE
working the design to go back to the component supplier but haven't heard
back from them yet.
Thanks

Gary McInturff
Reliability/Compliance Engineer

Esterline Interface Technologies
Featuring
ADVANCED INPUT, GAMESMAN,
and LRE MEDICAL  products
600 W. Wilbur Avenue
Coeur d'Alene, ID  83815-9496
Toll Free: 800-444-5923 X1XXX
Tel:  (208) 635-8
Fax: (208) 635-8

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Re: [PSES] Audio sources, class D digital amps, radiated emissions, and philosophy

[Brent DeWitt]

Great subject Doug and one very close to my heart (or head, whatever)!  

 

As an EMC engineer for Bose Corporation, I get to see a lot of audio
amplifiers with output levels from 10s of watts to thousands of watts.  The
extension to your article that I would like to make is that not all Class
D amplifiers are created equal.  Various chip manufacturers have different
approaches to how the switched (and therefore Class D) signal is produced.
One of the most troublesome is a vendor whose chip family produces equal and
balanced square waves on both wires to the speaker driver when no audio is
present.  While differential mode current is minimal with no input, common
mode di/dt charging currents down the wires to the driver can be quite high
and have very high frequency components.  On the order of 80% of our
products that I have tested in the last 5 years have highest emissions
profiles when the source is muted.  For European standards this is mitigated
by a standard test method in EN55013 of using IEC Pink Noise with a 6dB
crest factor and 20Hz to 20kHz pass band at 1/8 of maximum power.  Then we
get to the US/Canada where it's find the worst case.  You can guess which
is easier to pass!  The Pink Noise dithers the pulses on either side of the
driver leads and produces a very favorable spreading function in the higher
harmonics of the amplifier chopping frequency, such that radiated
emissions are significantly reduced.  Conducted emissions also benefit.

 

Bottom line is that I highly recommend that any EMC engineer first
familiarize themselves with the characteristics of the amplifier chip vendor
before launching into troubleshooting.  It will save you time in the long
run!

 

With respect,

Brent DeWitt, Senior EMC Engineer

Bose Corporation, Framingham MA

 

From: Doug Smith [mailto:d...@emcesd.com] 
Sent: Tuesday, August 19, 2014 7:13 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Audio sources, class D digital amps, radiated emissions, and
philosophy

 

Hi All,

Just finished and posted my August 2014 Technical Tidbit titled:

Radiated Emissions Can be Strongly Affected by Driving Signals, A Problem
for Emissions Testing
(An Example Using a Class D Stereo Audio Amplifier)

 

Abstract: Radiated emissions from electronic equipment can be a strong
function of how the equipment is operated. In the case of class D audio
amplifiers, the audio signal driving the amplifier can have a large effect
on emissions. Test results and implications are discussed as they relate to
the philosophy of radiated emissions testing.

The link to the article is: http://www.emcesd.com/tt2014/tt081914.htm

The link to the main page: http://www.emcesd.com/
(lots of new stuff there)

Check to make sure your computer does not corrupt the links above. They
should look just as above with no other symbols or numbers added as Windows
sometimes does at the end of the link of the form [1].

Doug



-- 
University of Oxford Tutor
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom 
--
 ___  _Doug Smith
  \  / )   P.O. Box 60941
   =   Boulder City, NV 89006-0941
_ / \ / \ _TEL/FAX: 702-570-6108/570-6013
  /  /\  \ ] /  /\  \  Mobile:  408-858-4528
 |  q-( )  |  o  | Email:   d...@dsmith.org
mailto:d...@dsmith.org 
  \ _ /]\ _ /  Web: http://www.dsmith.org
--

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Attachments

Re: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?

[Brent DeWitt]

Title: Re: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?
The small chamber with the lights was the work of Mike Hatfield, then of NSWC Dahlgren.Brent DeWitt-Original Message-
From: Luke Turnbull 
Sent: May 10, 2013 7:07 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?
















I’ve seen this on a video related to Frank Leferink’s reverb tents, where the modes are stirred by shaking the side wall of the tent. The fabric is think enough
 to see the tube inside.

Luke Turnbull



From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]
On Behalf Of Ken Javor
Sent: 09 May 2013 18:17
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?



There is a nice little demo that one can usually see at the EMC Symposium where someone (don’t recall who) has a small reverb chamber with some
 fluorescent lamps that come on and go off as the paddle is stirred.

Ken Javor
Phone: (256) 650-5261





From:
Ed Price edpr...@cox.net
Date: Thu, 9 May 2013 10:04:56 -0700
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?

I view the power density concentrations as varying density little clouds, chimera, moving regularly in 3 dimensions, and continuously changing their dimensions as they move.
 The presence of the ground plane, stirrer supports, antenna and EUT would have the motions not always linear. The motions wouldn’t be “darting” but more gracefully oscillating; it would make for one heck of an animation.

One thing we haven’t talked about is knowing the response time of your EUT. Most times, I was fortunate enough to be testing systems which had the courtesy of crashing rather quickly and completely, so a “response” was obvious. But when your definition of a
 “response” is “any degradation of operation, any unintentional responses and nor any failure of intentional responses”, then you have a formidable task before your testing just to learn how your EUT degrades.



Ed Price
WB6WSN
Chula Vista, CA USA


From: Ken Javor [mailto:ken.ja...@emccompliance.com]

Sent: Thursday, May 09, 2013 8:10 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?

Well, an area of constructive or destructive interference is going to have dimensions on the order of a half-wavelength. That sets the upper bound on the illumination spot-size. Clearly, the spot size decrease with increasing frequency.

Ken Javor
Phone: (256) 650-5261



From: 
Luke Turnbull luke.turnb...@trw.com
Date: Thu, 9 May 2013 09:53:35 +
To: Ken Javor ken.ja...@emccompliance.com, "EMC-PSTC@LISTSERV.IEEE.ORG" EMC-PSTC@LISTSERV.IEEE.ORG
Conversation: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?
Subject: RE: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?

The picture I have in my mind is that there’s a (or several) relatively small hot spot(s) – you could say will-o’-the-wisp(s) – that dart around the test chamber as the paddles move. Therefore
 my understanding is that a large system isn’t simultaneously illuminated by the reverb method.

Luke Turnbull


From:
emc-p...@ieee.org [mailto:emc-p...@ieee.org]
On Behalf Of Ken Javor
Sent: 04 May 2013 17:52
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?

Let me recode that – sorry for the typos:

The paddle must spin slow enough – or stop and dwell - so that the test sample has time to respond to the peak field intensity. Since one doesn’t know where in the chamber the peak is, only its amplitude, the rotation rate or dwell time must be such that the
 test sample response time is accommodated at every paddle position. This makes reverb testing take much longer than anechoic testing.

Ken Javor
Phone: (256) 650-5261 




From: Ken Javor ken.ja...@emccompliance.com
Date: Sat, 04 May 2013 11:49:23 -0500
To: EMC-PSTC@LISTSERV.IEEE.ORG
Conversation: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?
Subject: Re: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?

He paddle must spin slow enough – or stop and dwell, so that the test sample has time to respond to the peak fed intensity. Since one doesn’t know where in the chamber the peak is, only its amplitude, the rotation rate or dwell time must be such that the test
 sample response time is accommodated at every paddle position. This makes reverb testing much longer than anechoic testing.

Ken Javor
Phone: (256) 650-5261



From:
Pat Lawler plawl...@gmail.com
Date: Sat, 4 May 2013 08:36:58 -0700
To: owner-emc-p...@listserv.ieee.org
Cc: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Mode-stirred, Mode-tuned, Reverb - what's the difference?

The issue of 

Re: [PSES] LED Chamber Lighting

[Brent DeWitt]

One of my colleges here tested the X-prize Phillips bulb for radiated emissions 
in a simple desk lamp in our chamber.  A single bulb _barely_ passed Class B at 
three meters. 

YMMV!

Brent DeWitt
Bose Corporation
Framingham, MA


-Original Message-
From: Kunde, Brian brian_ku...@lecotc.com
Sent: Feb 4, 2013 1:22 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] LED Chamber Lighting

Has anyone tried out LED Lighting in EMC test chambers? If so, can you share 
your experience, opinions, likes and dislikes, and cost?

I have recently seen several ads for LED Light Fixtures and replacement kits 
where a 100watt LED light can replace a 400 watt Metal Halide bulb or fixture. 
But I have some concerns:

1. Are LED as bright?
2. The ETS-Lindgren datasheet claims No RF Noise into the test chamber. 
Seems too good to be true. Are these lights special for ETS or are there over 
the counter LED fixtures that will work just as well?
3. Cost? Are there generic lights that would work as well but be cheaper? If I 
hold off a year or two do you think the price will drop significantly?
4. What other pros and cons are there?


We have eight metal halide light fixtures in our chamber. Currently we have to 
replace the bulbs every two years because of rf emissions from bulb arcing. We 
replace the ballasts at 10 years because of loud buzzing. Though the metal 
halide bulbs are relatively inexpensive, we have to rent a lift for several 
days to work on the lights. Plus the cost of having the lights worked on every 
other year and our chamber being down for a few days. LED lights have the 
potential of being maintenance free for 15 years or more. In the long run it 
should save us money. This might be something to put on my capital equipment 
list for next year.

I'm curious to hear any input you might have on this topic.

Regards,
The Other Brian




LECO Corporation Notice: This communication may contain confidential 
information intended for the named recipient(s) only. If you received this by 
mistake, please destroy it and notify us of the error. Thank you.

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Re: [PSES] 61000-4-3: Rate of application of field

[Brent DeWitt]

In a previous life working with medical equipment (2 Hz modulation, 15 second dwell), I found that the transient from turning on the modulation at a random phase angle was sometimes problematic. My solution was to use an arbitrary waveform generator as the external modulation source to the signal generator. When commanded it would generate 30 cycles of sine wave, starting and stopping at the zero crossing.Respectfully,Brent DeWittMilford, MA-Original Message-
From: "Pawson, James" 
Sent: Aug 20, 2012 5:53 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] 61000-4-3: Rate of application of field











Hello,

I can't find any clauses in 61000-4-3 (radiated RF immunity) that deal with the rate of application of the RF field.

My understanding is that the test is generally performed by setting the unmodulated carrier to the level contained within the calibration file and then suddenly applying the modulation.

Is there any precedent for, or problem with, gradually increasing the modulated carrier field strength up to the required level instead of a more sudden application?

I imagine a system like a mobile radio would involve a suddenly applied burst of RF when the transmitter is "keyed".

Many thanks
James




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RE: Question on RF conversion

[Brent DeWitt]

Lisa,

You can't translate it until you specify a distance, at minimum.  The power
you are specifying radiates on to a spherical surface of an area which
increases as the square of the distance from the source.  There are a number
of variables that can enter into the final answer, so I'll stop short of a
longer dissertation and ask you to more fully describe the problem.

With respect,

Brent DeWitt

 -Original Message-
 From: owner-emc-p...@listserv.ieee.org
 [mailto:owner-emc-p...@listserv.ieee.org]On Behalf Of
 lisa_cef...@mksinst.com
 Sent: Thursday, January 13, 2005 6:31 AM
 To: emc-p...@ieee.org
 Subject: Question on RF conversion


 Good morning all,


 Quick question, maybe..

 If I have a Walkie Talkie that emits 5W at 430MHz, how does this translate
 to V/m so that I can correlate
 the field strength with radiated immunity testing?

 Thank for any input

 Regards,

 Lisa

 
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ISO 14971 question

[Brent DeWitt]

Scanning the broad range of knowledge on theis list I have the following
question:

Does anyone know of a standard other than 60601-1-2 that untilizes ISO 14971
risk analysis under normal rather than single fault conditions?

Thanks!

Brent DeWitt
Datex-Ohmeda
Louisville, CO



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RE: Q. on Res Bandwith performace traceabiity

[Brent DeWitt]

This is getting a wee bit silly.  First (to be terribly nit-picky) it's dB
not db.  The unit is a Bel.  Second, dBm does not carry with it an impedance
specification.  The milliwatt reference can be into anything slightly less
than infinity to slightly greater than zero.  Third, I believe dBV is dB
referenced to one volt.  The factor of two difference in power and voltage
is simply the effect of pulling the log of the voltage squared term outside
of the log operation.  Not a great mystery.

Are we done now?

Brent DeWitt


From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of
f...@dctolight.net
Sent: Tuesday, September 02, 2003 2:21 PM
To: ken.ja...@emccompliance.com
Cc: f...@dctolight.net; cgrassospri...@earthlink.net; emc-p...@ieee.org
Subject: Re: Q. on Res Bandwith performace traceabiity




 Incorrect.  A dB is a dB.

Correct! But who is talking about db? I'm sure you know that db is a
dimensionless ratio. I believe we were discussing power.

Let’s make sure we all have the formula:

db =  10 log (P1/P2)   or

   =  20 log (V1/V2) + 10 log (Z2/Z1)

A quick scan of the formula will show that we multiply the voltage term by
twice as much as the power term. Also, if Z1=Z2, then we have 10 log of 1
or zero so the impedance (resistance in this case) term drops out.

OK now here is the important part. To convert db from a ratio to units of
power we define 0dbm = 1mwatt into 600 ohms. Since not everyone measures
power we also define 0dbv = 1 mvolt into 600 ohms. Since a millivolt into
600 ohms is not a milliwatt into 600 ohms, using the formula P = (V
squared)/R, we find that 0 dbm is (almost) equal to 6 dbv  into 600 ohms.

Finally back to the point at hand, if the scale on our meter is in dbm
then the half power point is at -3 dbm  (not -3 db). If the scale is in
dbv then the half power point is – 6 dbv (not -6db). In this context -3
dbm is equivalent to -6 dbv.  I apologize to all for using the equal sign
instead of the equivalent.  I think my statements are otherwise accurate.
And to give Ken his due, a db is unquestionably equal to itself.

QED


Fred Townsend






3 dB down is half power but 70.7% voltage.  6
 dB down is 1/4 power, or one half voltage or current.


 on 8/31/03 10:42 AM, f...@dctolight.net at f...@dctolight.net wrote:


 A few basics: If we are talking about power points (no software puns
 intended) then it is the 3 db points.  If we are taking about voltage
 (or current) points then it is the 6 db points.  As the professors
 would say, it is left to the student to prove that 3 dbm = 6 dbv
 through the formula P = EE/R.
 QED?

 My understanding is that it is the 6 dB points which are cited as the
 bandwidth.  I'm not up on CISPR 16 but to entirely specify the
 bandwidth the 60 dB down points are also specified.  The slope you
 get from the 6 dB to the 60 dB points is called the shape factor.
 From: Charles Grasso cgrassospri...@earthlink.net
 Reply-To: Charles Grasso cgrassospri...@earthlink.net
 Date: Thu, 28 Aug 2003 07:06:13 -0700
 To: Emc-Pstc emc-p...@ieee.org
 Subject: Q. on Res Bandwith performace traceabiity


 Greetings:

 Does anyone know if the Resolution Bandwidth
 filter performance is tracable to a given standard
 and which standard that might be?

 I was wondering if the rool-off after the 3dB points
 is specificed as a standard for ALL analysers.

 I am assuming that the anaswer is Yes as chaos
 would reign!!

 ---
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RE: Synchronizing DC-DC converters to reduce emissions?

[Brent DeWitt]

Pat,

I agree with you and would avoid syncronization.  Another consideration is
using pulse position modulation rather than pulse width modulation.  PWM
only changes the ratio of odd to even harmonics of the switching frequency
while PPS spreads the peak energy and may lower the emission peak within the
CISPR bandwidth.

Brent DeWitt


From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Pat Lawler
Sent: Wednesday, July 30, 2003 8:31 AM
To: EMC-PSTC
Subject: Synchronizing DC-DC converters to reduce emissions?



We are designing a switching power supply for a customer that has
multiple outputs.  Due to the tight regulation requirements, all
outputs have their own PWM modulators and control loops.

The customer feels the RF emissions (as measured by CISPR 11) will be
reduced by synchronizing the frequencies of all the converters.  I
think synchronizing the PWM sections will make the total power supply
emissions as high as possible (emissions are coherent?).

1) What has been your experience with controlling noise from multiple
switching power supplies?  Is synchronizing a good idea?

2) If the supplies are synchronized, would a phase shift between
converters (avoiding simultaneous switching of all converters) help?

Thanks,
---



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RE: RTTE for Medical Devices?

[Brent DeWitt]

Del,
 
I'm not an RTTE expert, but from the MDD side under the 2nd edition of
60601-1-2 (2001), the function of the card and it's communications would have
to be evaluated.  If it falls under the ESSENTIAL FUNCTION of the medical
device, it would be subject to the requirements of 60601-1-2.  These
requirements are somewhat more stringent than the RTTE directive.
 
That probably doesn't help much, but it's a bit more information.
 
Regards,
 
Brent DeWitt


From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of D.Han
Sent: Friday, July 18, 2003 4:20 PM
To: emc-p...@majordomo.ieee.org
Subject: RTTE for Medical Devices?



Hi All,


I would appreciate your thoughts on the following scenario:

 

Company A designs a medical product that incorporates a wireless device, lets
say, a wireless PCI card. The wireless card is manufactured by Company B and
has been evaluated to the RTTE directive and thus CE-marked. This wireless
card is installed in the end medical product, unmodified and according to
manufacturers instructions.

 

Company As name goes onto the end product, but Company Bs name, markings,
labeling etc. remain on the wireless card. Would Company A need to consider
RTTE (in addition to the MDD) for their end product? If yes, what additional
testing would this encompass? 

 

Thanks!

Del



  _  

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SBC  http://pa.yahoo.com/*http://rd.ya
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RE: EMC-Related Functional Safety

[Brent DeWitt]

Gregg,
 
As an EMC engineer and a member of the IEC committee that wrote the 2nd
edition of IEC 60601-1-2, I find your challenge interesting.  First, I have
to say I was not impressed with the referenced article.  Facts were played a
little bit too loose for my preferences.  That said, I strongly believe that
EMI is an inseparable portion of product safety.  You mention that EMC
interferes and I agree.  When it interferes with a wheelchair controller and
drives the patient into traffic or causes an infusion pump to triple the drug
delivery rate, it can kill.  I don't believe I have enough product safety
experience to say if those same failures could have been caused by single
component faults, but I suspect that a real world examination of the product
has a significant possibility of missing the single component that was
effected.  I can say from 15 years or so experience that it takes much less
than a microwave oven to cause medically critical control electronics to
misbehave.
 
Regards,
 
Brent DeWitt
Datex-Ohmeda
Louisville, CO

From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Gregg Kervill
Sent: Tuesday, February 11, 2003 12:14 PM
To: 'Richard Hughes'; 'drcuthbert'; emc-p...@majordomo.ieee.org
Subject: RE: EMC-Related Functional Safety


I fully agree with Richard Hughes – it is an interesting article but those
of us who have conducted “Flight Safety” work will find it VERY weak is
its content and treatment.
 
 
Whilst EMC interferes (unless you are sitting in a microwave oven) - it is
Product Safety (or the lack thereof) that kills!
 
 
Furthermore I challenge anyone to demonstrate that the EMC related fatalities
could not have been caused by a single components failure.
 
 
 
 
Best regards
 
Gregg
 
 

From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Richard Hughes
Sent: Tuesday, February 11, 2003 11:01 AM
To: 'drcuthbert'; emc-p...@majordomo.ieee.org
Subject: RE: EMC-Related Functional Safety
 
Dave, 
As you say, an interesting article. 
Note however that it states in regard to the LVD that: 
The Low Voltage Directive (LVD) 
Although the LVD (73/23/EEC, modified by 93/68/EEC) is generally reckoned to
cover functional safety, there are no words in its text that specifically
mention it - never mind EMC-related functional safety
While this is accurate as far as it goes (and remembering that the Safety
Objectives of the LVD were published in 1973), it could give people a false
impression.
The February 2001 version of the Commission publication GUIDELINES ON THE
APPLICATION OF COUNCIL DIRECTIVE 73/23/EEC states:
The Commission interpret that all electromagnetic aspects relating to safety
including functional safety are covered by the LVD.
 
Many of you will be aware that a revision to the LVD is underway.  At the
present state of discussions the draft essential requirements are far more
detailed than the old safety objectives and certainly include this issue. 
Of course, what the final text will be is not known with certainty at this
time.
Regards, 
Richard Hughes 
Personal opinions only, of course. 
 
-Original Message- 
From: drcuthbert [ mailto:drcuthb...@micron.com] 
Sent: 10 February 2003 19:27 
To: emc-p...@majordomo.ieee.org 
Subject: EMC-Related Functional Safety 
 

OFF TOPIC, was RE: David Sproul...UL creepage limits ;~)

[brent . dewitt]

The actual reason for not connecting the negative terminals directly when
jumpering two cars is the risk of hydrogen explosion in the presence of a
spark.  Positive terminals are connected first, then the negative
connections made somewhere away from the battery vents.  I happened to be
at a Checker Auto last year when one of their personnel blew up a customers
battery (in the car) while using their system tester.  Quite the bang.
Fortunately, no one was hurt.

Regards,

Brent DeWitt






Peter L. Tarver peter.tar...@sanmina-sci.com@majordomo.ieee.org on
10/10/2002 08:58:40 AM

Please respond to Peter L. Tarver peter.tar...@sanmina-sci.com

Sent by:  owner-emc-p...@majordomo.ieee.org


To:   Ted Rook t...@crestaudio.com,  emc-p...@ieee.org
cc:

Subject:  RE: David Sproul...UL creepage limits ;~)



Jeeze, Ted.  I think your carb chain is loose.

 -Original Message-
 From: owner-emc-p...@majordomo.ieee.org
 [mailto:owner-emc-p...@majordomo.ieee.org]On
 Behalf Of Ted Rook
 Sent: Wednesday, October 09, 2002 7:28 AM
 To: 
 Subject: David Sproul...UL creepage limits ;~)



 This is because when you double the voltage the
 power is proportional to a quarter of the current
 squared. In America the 120V power is at lower
 voltage but the current is twice as much and so
 the creepage is twice as well.

 Very high voltage circuits hardly creep at all
 whereas low voltages creep the most. That is why
 you should never join the two negative terminals
 when you jump start a car, the car battery
 charging circuits have so much creepage they can
 melt the battery.

 I though everybody knew that...



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Re: Difference between Receivers and Spectrum Analyzers

[brent . dewitt]

The lines between spectrum analyzers and receivers have grown very fuzzy,
but in the old days the biggest difference was that a receiver had a
narrow band tuned front end and an S.A. had a broadband one.  This makes
the S.A. more susceptible to out of band interference.  I certainly
wouldn't say that an S.A. is only a qualitative device.

Regards,

Brent DeWitt


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RE: Surge and EFT test equipment for AC, DC, and signal ports

[Brent DeWitt]

Jim,

Having run a test lab in a previous life, I'd have to say that the price
mentioned is _way_ high since it doesn't include radiated immunity.  What's
a little unusual is your very high power demands.  I suspect there are not
more than a dozen labs in the US that can deal with 500 Amp DC inputs and
12kW outputs.  There may be a premium there.

Respectfully,

Brent DeWitt

-Original Message-
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Warren Birmingham
Sent: Monday, September 23, 2002 8:03 PM
To: Jim Eichner
Cc: emc-p...@majordomo.ieee.org
Subject: Re: Surge and EFT test equipment for AC, DC, and signal ports



Jim, it is just my opinion, but well-designed equipment does not have
much risk of failure for the majority of the tests.  The one test that
is worth some investment is an ESD test device.  I believe that this is
the most commonly-failed test and often the most difficult to correct
without some insight. The remainder of the equipment you will need will
cost about $60,000 and given that you may spend test money at a
laboratory anyway is likely not worth it unless you are a very big
manufacturer that can benefit from ISO 9000:2000 without doing the 3rd
party testing.  As a minimum, you are likely going to have to deal with
calibration and service issues and the delays associated with them.

A suite of testing runs about $6000 for immunity for ITE equipment to
meet EN 55 024 without even talking about the Radiated Immunity
requirements equipment and a chamber.  You are going to likely have to
do this subset of testing anyway if you want a credible report as
evidence of self-declaration.  The costs of emissions and immunity
testing with reports is around $7000 and is a clean approach both
financially and in timeline if you do some chamber tests first for
emissions, say a 2-hour scan in a chamber.  Emissions and immunity
testing are somewhat coupled in that a device that is a low radiator is
also likely to have good resistance to susceptibility, but not always.
This is most often true of metal shielded enclosures and those with
shielded I/O cables.

If you want to give me a call I'll share what I know.

Warren Birmingham
Epsilon-Mu Consultants
(510) 793-4806
email: war...@epsilon-mu.com
website: http://www.epsilon-mu.com


On Monday, Sep 23, 2002, at 14:44 US/Pacific, Jim Eichner wrote:


 We are starting to look into the costs and issues around gearing up
 for
 some immunity testing, with the intent of determining whether or not
 it is
 too hard or too expensive to gear up to do some of it at home. We
 are
 not looking for final formal compliance results here, only for
 pre-compliance peace of mind. In particular, I need to consider the
 following:

 1. EFT (EN61000-4-4) - AC input, output, and ground lines, DC input
 and
 output lines, signal/control lines
 2. Surges (EN 61000-4-5) - AC input, output, and ground lines, DC
 input
 and output lines, signal/control lines
 3. Surges (SAE J1113/11) on DC power leads
 4. Fast transients (SAE J1113/12) on other than power leads

 The products which we hope to be able to test in-house are power
 conversion and control products, and have a wide range of input/output
 voltages and power:

 - AC inputs up to 120V, 60A, or 230Vac, 30A single-phase, 120/240V,
 50A,
 split-phase, and 120/208V, 30A, 3-phase
 - AC outputs up to 120Vac, 60A, 230Vac, 30A, 120/240V, 50A split-phase
 - DC inputs up to 12V, 500A; 24V, 300A; 48V, 200A
 - DC outputs up to 12kW at 10 - 600Vdc (1200A - 20A)

 Questions:

 1. Is there any single piece of equipment (with
 accessories/modules/etc.)
 available that can do both Surge and EFT tests on equipment, or are
 these
 tests just too different?

 2. Surge - Is there any single piece of equipment (with
 accessories/modules/etc.) available that can do surges on all these
 types
 of ports: AC and DC and signal/control?  Any info re mfr, cat. no.,
 price,
 etc. would be appreciated.

 3. EFT - Is there any single piece of equipment (with
 accessories/modules/etc.) available that can do EFT on all these
 types of
 ports: AC and DC and signal/control?  Any info re mfr, cat. no.,
 price,
 etc. would be appreciated.

 4. Do these tests have to be run at full output (which may limit my
 ability to find 3rd party labs with suitable equipment, let alone
 gear up
 in-house) or can they be run with a light load on the equipment and
 then
 test full output after each test to confirm return to normal
 operation?

 Thanks in advance for your help,
 Jim Eichner, P.Eng.
 Regulatory Compliance Manager
 Xantrex Technology Inc.
 e-mail: jim.eich...@xantrex.com
 web: www.xantrex.com
 Any opinions expressed are those of my invisible friend, who really
 exists.  Honest.  No, really.
 Confidentiality Notice: This email message, including any
 attachments, is
 for the sole use of the intended recipient(s) and may contain
 confidential
 and privileged information. Any unauthorized review, use, disclosure

RE: Radiated immunity test

[Brent DeWitt]

Hi KC,

His information is nothing really new, just stated differently.  The
standard modulation is 80% AM at 1 kHz, so the modulated field strength will
be 1.8 times the unmodulated level.  61000-4-3 spells this out fairly
clearly.  I've never done a calibration of field uniformity with modulation
on and I think that it is a bad idea since the field sensor may be effected
by the modulation.  That said, and after the chamber calibration is done,
the power amplifier system _must_ be checked for clipping at the highest
required forward power.  I know of more than one commercial lab that passed
field uniformity, but had clipped power amplifier output under modulation.

Respectfully,

Brent DeWitt


-Original Message-
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of KC CHAN [PDD]
Sent: Monday, September 23, 2002 7:57 PM
To: emc-p...@ieee.org
Subject: Radiated immunity test



Dear All

I just discussed with a supplier about the upgrade to 2GHz of the
IEC61000-4-3, he showed me a document which says that the calibration of the
field strength needs to be 1.8 greater then the required field, eg. for
10V/m, 18V/m is required for calibration to ensure the system can produce
10V/m with modulation.

Since the deadline of testing above 1 GHz is coming for radio testing, this
new requirement would definitely affect the decision of the system upgrade.
Appreciate if anyone can advise more information about this.

Best Regards
KC Chan


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Transmission line formula?

[brent . dewitt]

Anyone have a formula for calculating the Z0 of two parallel rectangular
pieces of metal tubing in air?  I'm designing a log-periodic antenna and
need to get the boom transmission line spacing right.

Thanks!

Brent DeWitt
Datex-Ohmeda


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RE: made in xxxx requirements?

[Brent DeWitt]

Gary,

Sorry.  It's Medical Electrical Equipment.  Both the MDD and FDA have been
searched with no apparent need for this marking, but this may not be
correct.

-Original Message-
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Garry Hojan
Sent: Thursday, July 18, 2002 6:47 PM
To: brent.dew...@us.datex-ohmeda.com; emc-p...@majordomo.ieee.org
Subject: RE: made in  requirements?



Hello Brent,

Can you let us know the basic category of product? The marking requirements
for Country of Origin vary depending on the product and of course, the
country that the product is intended to be marketed in. There will be two
areas that you might have to address this issue, first in the labeling
requirements for an approval, and secondly in the pro forma invoice for
customs and excise.

Best regards,
Garry Hojan
CEO/ President
Strategic Compliance Services (SCS)
a Division of NRL, L.L.C.
11402 E Mariposa Rd.
Stockton, CA 95215
Tel:209-465-0619
Fax:209-812-1931
Mobile: 209-662-4322
Email:  gho...@regulatory-compliance.com
Web:www.regulatory-compliance.com



-Original Message-
From:   owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of
brent.dew...@us.datex-ohmeda.com
Sent:   Thursday, July 18, 2002 4:22 PM
To: emc-p...@majordomo.ieee.org
Subject:made in  requirements?


This is not my usual area of interest, but a question came up about
regulations for country of origin marking, either in the US or EU.  Can
anyone point me in the direction of an answer?

Thanks all,

Brent DeWitt
Datex-Ohmeda
Louisville, CO


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made in xxxx requirements?

[brent . dewitt]

This is not my usual area of interest, but a question came up about
regulations for country of origin marking, either in the US or EU.  Can
anyone point me in the direction of an answer?

Thanks all,

Brent DeWitt
Datex-Ohmeda
Louisville, CO


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Re: Re[2]: Non-metallic tables.

[brent . dewitt]

It's probably not an issue for most folks, but don't trust anything with a
dielectric constant much above that of expanded polystyrene above 1GHz.
Having been burned before.  I would suggest checking the characteristics of
anything you buy for rotational uniformity.  You need either a simple 1/4
wave vertical comb generator, or an isotropic field sensor.  Check either
the received field from the comb generator (or emissions) or the field seen
by the sensor (for immunity) every 10 degrees or so of turntable rotation.
I have data from a dry plywood table with a laminate surface that indicates
more that 8dB variation across the corners of the table at 1GHz.

Regards,

Brent DeWitt
Datex-Ohmeda
Louisville, CO






brian_ku...@leco.com@majordomo.ieee.org on 07/02/2002 08:19:23 AM

Please respond to brian_ku...@leco.com

Sent by:  owner-emc-p...@majordomo.ieee.org


To:   emc-p...@ieee.org
cc:

Subject:  Re[2]: Non-metallic tables.



Gary,

If cost is not a big factor, try contacting Sunol in California. The
contact I
have is Dale Guthery at (925) 485-9260 (but I haven't talked to them in
several
years).  I know a few years ago the were selling EMC test tables based on a
design of ours which had wheels that could be easily removed once you
rolled the
table into place.  I understood they were expensive but very nice tables.

Brian Kunde
LECO

Reply Separator
Subject:Re: Non-metallic tables.
Author: nick.willi...@conformance.co.uk
List-Post: emc-pstc@listserv.ieee.org
Date:   7/2/02 9:50 AM


Gary,

I may be missing the point, but my thoughts are drawn to roto-moulded patio
furniture of the kind one can purchase in DIY and other major chain
stores.

Rgds

Nick.


At 10:06 -0700 1/7/02, Gary McInturff wrote:
   I am looking for a non-metallic table I can put equipment on for
pre-pre-compliance checks. Was thinking of Rubbermaid Corp or the likes,
but first blush says they don't have anything sufficiently close.
   Anybody our there buy rather than make the chamber test tables?
   Gary


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case of units

[Brent DeWitt]

I've always found it interesting that the small k is the only lower case
letter used for multipliers greater than unity.  I presume it is because the
temperature folks got there first with Lord Kelvin's initial.  Too bad
really since kilo has a linguistic meaning for numbers and Kelvin is just
a name.  Also rather interesting that we have no trouble using G for both
Giga and Gauss.

Just Sunday evening thoughts.

Brent DeWitt




-Original Message-
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of bogdan matoga
Sent: Saturday, June 22, 2002 6:55 PM
To: Robert Wilson
Cc: TM66; emc-p...@majordomo.ieee.org
Subject: Re: SI Unit for volume



Bob:
When you go for SI then please stay with the convention, i.e. kilowatt is
abbreviated as kW and not KW. We are hopefully beyond the time when MAmp was
supposed to mean milliampere.
Regards,
Bogdan.

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Re: Input voltage range - EN61000-4, 5 and 6

[brent . dewitt]

In the very specific case of Medical devices, the newest edition of IEC
60601-1-2 specifies -5 testing at the extreme ends the range of
continuously adaptive supply and in each range of a switched range supply.

Regards,

Brent DeWitt






gunter_j_ma...@embraco.com.br@majordomo.ieee.org on 04/18/2002 12:25:38 PM

Please respond to gunter_j_ma...@embraco.com.br

Sent by:  owner-emc-p...@majordomo.ieee.org


To:   emc-p...@majordomo.ieee.org
cc:

Subject:  Input voltage range - EN61000-4, 5 and 6



List

I suppose that EN61000-4-4, 4-5 and 4-6 do not mention the input voltage to
be applied to the EUT during the tests.
For a product with a voltage range, like 198 up to 264Vac (230Vac nominal),
what should be the right value ?
Or do I need to look for the worst voltage case  ?

Thank you for your time.

Günter J. Maass
Researcher - Power Electronics Development
EMBRACO S.A.



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RE: Committee Memberships

[Brent DeWitt]

Martin,

To the best of my understanding, for international committees (IEC and
TAGs), it requires the endorsement of your nomination by the appropriate
National Committee.  ANSI typically reviews resumes directly for committee
applicants.

regards,

Brent DeWitt

-Original Message-
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of
marti...@appliedbiosystems.com
Sent: Wednesday, March 27, 2002 5:12 PM
To: emc-p...@majordomo.ieee.org
Subject: Committee Memberships



To all,

I am trying to find out what is required of an individual to become a
member of committees that are responsible for creating standards.  These
committees would include, but not limited to, IEC Technical Committees,
Working Groups and ANSI Standards Committees.

My question is extremely general since I am trying to gather any and all
information on this process. I am sure that many  members of this forum are
involved in various committees that are responsible for creating standards.
Hopefully, you can shed some light on this issue.

All responses are greatly appreciated.

Regards

Joe Martin
Compliance Engineering
Applied Biosystems
marti...@appliedbiosystems.com




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RE: High Frequency Pre-amp

[Brent DeWitt]

Robert brings up a very good point.  It is the main difference between a $4
ERA monolithic amp from MiniCircuits and a packaged $1200 Miteq amp.  While
saying that, I think MiniCircuits is a great company with a range of
products that are well characterized and worth every penny.

Regards,

Brent DeWitt

-Original Message-
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Robert Macy
Sent: Friday, December 21, 2001 1:09 PM
To: Ken Javor; rehel...@mmm.com; emc-p...@majordomo.ieee.org
Subject: Re: High Frequency Pre-amp



Just a reminderalways make certain that no signal gets in to saturate,
or even start to overdrive, your amplifier at frequencies you're not looking
at.

- Robert -

   Robert A. Macy, PEm...@california.com
   408 286 3985  fx 408 297 9121
   AJM International Electronics Consultants
   619 North First St,   San Jose, CA  95112


-Original Message-
From: Ken Javor ken.ja...@emccompliance.com
To: rehel...@mmm.com rehel...@mmm.com; emc-p...@majordomo.ieee.org
emc-p...@majordomo.ieee.org
List-Post: emc-pstc@listserv.ieee.org
Date: Friday, December 21, 2001 11:42 AM
Subject: Re: High Frequency Pre-amp



MITEQ and Mini-Circuits come to mind for octave and multi-octave  band
amps.
HP (Agilent) makes the the 8348A covering 1 - 26.5 GHz around $14 K.  The
HP
model has a 10 dB noise figure and 25 dB gain below 20 GHz.  With MITEQ you
can pick your noise figure and gain from a large variety of models.
Mini-Circuits is the low price leader, I saw amps up to 8 GHz but you would
need several models and the price will still likely be less than with the
others.  If you are using an HP8566 or similar model which uses harmonic
mixing above 2 GHz then you need enough gain to push the signal above the
degraded noise floor.

--
From: rehel...@mmm.com
To: emc-p...@majordomo.ieee.org
Subject: High Frequency Pre-amp
Date: Fri, Dec 21, 2001, 10:16 AM



 This question may have recently posted but I'm not able to search the
 archives so I'll
 ask again.

 We have an immediate need for a pre-amp above 1000 MHz. Would you be so
 kind
 as to let me know what brands/models and frequency range you are using.
Any
 pro/con
 insights would be welcome as well. Please contact me on or off-line.

 Thanks,
 Bob Heller
 3M Product Safety, 76-1-01
 St. Paul, MN 55107-1208
 Tel:  651- 778-6336
 Fax:  651-778-6252


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RE: 2 Phases in North America

[Brent DeWitt]

Hi all,

Even though I am an electrical engineer, I'm terribly confused by this post.
I have always believed (and on a few occasions measured) the standard US
home system feed.  There is no choice of 240 volts.  The 220 volt feed
used by larger devices is two 118 VAC phases 120 degrees apart.  The math
seems to work.

WRT Cortland's post, I guess I don't see ground (or close to it neutral)
as having a phase.  If that is believable, then a single phase system is
not so hard to believe.

Just a few thoughts,

Brent DeWitt
  -Original Message-
  From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of bogdan matoga
  Sent: Friday, December 14, 2001 3:12 PM
  To: Cortland Richmond
  Cc: Robert Johnson; 'Barry Esmore'; 'EMC-PSTC Forum'
  Subject: Re: 2 Phases in North America


  Dear Esquire:
  May I suggest that you partake in a course called Basic Electricity 001?
  Bogdan.
  Cortland Richmond wrote:

 By the definition below, *single phase* AC would require one wire with
no return.  I want to see THAT one work before I pay for it!
Cortland Richmond
(the above being my own opinion, not a statement of my employer's)

Robert Johnson wrote:

  This has just reopened the old two phase controversy again. Ed has
done a good job of describing the systems in detail, but be careful with the
terms.
  Ask an electrical engineer about a 120/240 volt home service and he
will call it a two phase system. Two phases 180 degrees out of phase is
technically correct.
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IC marking ?

[brent . dewitt]

I'm trying to track down the data on a SO-8 protection diode array and I
don't recognise the package marking.  It's a circle made up of four stars
at 90 degree angles to each other.  I _think_ it might be the now obsolete
General Semiconductor symbol.  Can anybody point me to a reference?

Thanks!

Brent DeWitt


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RE: EMC test table construction plans

[Brent DeWitt]

I agree that wood and other high density materials are a problem as one
approaches 1 GHz.  I have data (taken in a previous life) that clearly shows
the effect of a wooden table with a Formica top.  This was done by placing
an isotropic field sensor (ok, close to isotropic) at the center of a table
and illuminating it from three meters away in a semi-anechoic chamber.
Field strength was measured at each ten degrees of rotation at several
frequencies up to 1 GHz.  The effect at 1 GHz was in excess of 6 dB
difference.  The interesting part is that what appeared to be happening was
low angle (below the critical angle) dielectric reflection.  The signal
was strongest when aligned with the corners of the rectangular table.

Brent DeWitt
Datex-Ohmeda
Louisville, CO

-Original Message-
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Sundstrom Michael
(NMP-RD/Dallas)
Sent: Friday, November 02, 2001 7:09 AM
To: 'Pommerenke, David'; 'POWELL, DOUG'; EMC-PSTC (E-mail)
Subject: RE: EMC test table construction plans



We use a styrofoam table here at our lab, it is a round plug of
styrofoam 80cm tall and 1m across. This has worked the best for us, and
it has the least reflections at any frequency we can reliably test at. I
would guess that some form of hard material on top of this type of table
would support 200lBs.

Michael Sundstrom
 NOKIA
  TCC Dallas / EMC
   ofc: (972) 374-1462
cell: (817) 917-5021
 amateur call: KB5UKT


-Original Message-
From: ext Pommerenke, David [mailto:davi...@ece.umr.edu]
Sent: Thursday, November 01, 2001 3:16 PM
To: 'POWELL, DOUG'; EMC-PSTC (E-mail)
Subject: RE: EMC test table construction plans



Doug,

For emissions and immunity you should not use any wood in the table. It
will
significantly (+/-2 dB up to 1 GHz for emissions , more above, +/-10 dB
for
immunity up to 1 GHz) change the test result. My experience has shown
that
Styrofoam is basicly the best material. There are a couple of published
papers on this issue. As surface material the following worked out fine:

  - Foamed PVC (rather stiff, low dielectric constant due to the foamed
nature), maybe 4 mm thick.

  - PE sheet, maybe 2 mm thick.

David Pommerenke



-Original Message-
From: POWELL, DOUG [mailto:doug.pow...@aei.com]
Sent: Thursday, November 01, 2001 11:38 AM
To: EMC-PSTC (E-mail)
Subject: EMC test table construction plans



Hello all,

I plan to construct my own insulated EMC test table for a 5 meter
chamber.
Seems simple enough to do and I could easily come up with something.  I
thought I might first ask for input from those of you in the discussion
group who have experience or maybe even construction plans.  Here are
some
features I want:

1) I will be testing products that weight up to 200 Lbs (91 kg).

2) I want to minimize metalic fastners.

3) I would like to make it a pivoting table (not motorized).

4) Height is 80 cm.

5) The surface should be replacable if it gets badly worn or scarred.
I'm
thinking of using hardboard.

6) Suggestions on length  width?

-doug

---
Douglas E. Powell, Compliance Engineer
Advanced Energy Industries, Inc.
Mail stop: 203024
1626 Sharp Point Drive
Ft. Collins, CO 80525

970.407.6410 (phone)
970-407.5410 (fax)
mailto:doug.pow...@aei.com
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board scanning on the cheap (sort of)

[brent . dewitt]

With all this talk about visualization, I thought I'd toss in my bit.

Here at Datex-Ohmeda we have a small NC mill sometimes used by the RD
group to make small prototype parts, but it often sits idle.  Since I have
a spectrum analyzer and a variety of small dimension H and E field probes
I've built, I thought it would be interesting to build the equivalent of an
EMScan.  The control program is being written in LabVIEW and is coming
along pretty well.  One nice thing about the mill is that I can program the
scan height for any rectangle I define, so tall components can be hopped
over.  When it's all done, I should be able to play a frequency swept
movie of the board on an intensity graph.  The cheaper way to do this
would be to find an older X-Y plotter and skip the height variation.  If I
ever get the beast done, it will be open source to LabVIEW users.

Best regards,

Brent DeWitt
Datex-Ohmeda
Louisville, CO


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