Re: [PSES] New LG Monitors and Wi-Fi

[Pawson, James]

No mention of what band (2.4GHz or 5GHz) is affecting the monitor. I’d agree 
with Stephen’s assessment in that it’s a bit of both.

From: Kortas, Jamison [mailto:jamison.kor...@ecolab.com]
Sent: 30 January 2017 16:50
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] New LG Monitors and Wi-Fi

What do you all think of this? Is this user error (too close), or a design 
issue?

https://9to5mac.com/2017/01/30/lg-ultrafine-5k-display-router-disconnecting/


Thanks,

Jamison
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Re: [PSES] lowest emissions 4k TV?

[Pawson, James]

Hi John,

You are right about impedance discontinuities being a factor.

However, in my experience with HDMI, these changes are swamped by a combination 
of SI imperfections made up of intra pair skew, amplitude imbalance and uneven 
rise/fall times within the HDMI data pairs. Adding common mode chokes only 
sorts out some of the problem, the rest has to be dealt with by using well 
constructed cables.

I did some simulation work on this a while back to show where the problem was 
coming from to highlight the problem to the silicon manufacturers we used at 
the time. They were very un-interested, not really their problem you see  :-(

I really should write all this up in an article at some point...

James



-Original Message-
From: John Woodgate [mailto:jmw1...@btinternet.com] 
Sent: 14 January 2017 10:14
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] lowest emissions 4k TV?

I think the key words 'poorly-constructed' should be noted. Any manufacturing 
defect that creates an impedance discontinuity in the signal conductors causes 
mode conversion of the differential signal, creating a small, but significant 
common-mode signal.

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: ce-test, qualified testing bv - Gert Gremmen [mailto:g.grem...@cetest.nl]
Sent: Saturday, January 14, 2017 9:57 AM
To: 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
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Phone :  +31 10 415 24 26
---

Re: [PSES] lowest emissions 4k TV?

[Pawson, James]

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]
Sent: 10 January 2017 01:57
To: 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] Automated vehicles.

[Pawson, James]

This article in The Guardian is related to your first point regarding human 
drivers “gaming” driverless cars to gain an advantage

https://www.theguardian.com/technology/2016/oct/30/volvo-self-driving-car-autonomous

“The first self-driving cars to be operated by ordinary British drivers will be 
left deliberately unmarked so that other drivers will not be tempted to “take 
them on”, a senior car industry executive has revealed.”

Also

“Meanwhile, Mercedes has made it clear that if a situation arises where a car 
has to choose between saving the lives of its occupants or those of bystanders, 
it will save the occupants. ‘If you know you can save at least one person, at 
least save that one. Save the one in the car,’ Christoph von Hugo, manager of 
driver assistance systems and active safety at Mercedes, told the Paris Motor 
Show recently.”

Bruce Schneier writes a lot on security issues and regularly covers IoT and 
occasionally driverless vehicles. His blog makes for interesting reading - 
https://www.schneier.com/  I’m sure it will end up being the usual round of 
addition of features, poor programming/testing (due to budget constraints), 
vulnerabilities, exploiting, patching, public outcry, legistlation, etc.

All the more reason to buy a bicycle.

James



From: Doug Powell [mailto:doug...@gmail.com]
Sent: 06 November 2016 02:17
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Automated vehicles.

Although it's Saturday, I'll use this as my Friday Question.


In light of two recent reports in the InComplisnce Magazine.  I feel prompted 
to ask if anyone on this forum can address a couple of questions.

http://incompliancemag.com/u-s-dot-releases-federal-policy-on-automated-vehicles/

http://incompliancemag.com/uber-self-driving-truck-delivers-budweiser-beer/

Aside from the obvious concerns about vehicle safety, it occurs to me that 
there two problem that presently are missing in recent media reporting.  In 
particular for the Level 4 & 5 vehicles as described by the SAE and DOT report.

1) I understand that these vehicles, such as the fully automated Budwiser truck 
have avoidance systems. Given the human condition of today, I foresee the 
distinct possibility of drivers in other vehicles "playing around" in such a 
way as to try and force a response from the avoidance algorithms and cause 
these vehicles to crash themselves.  This kind of sport would be exactly what 
some types would enjoy. What sort of preventative measures have been taken in 
this regard?

2) Given the lack of attention to hacking we have already witnessed in the 
Internet of Things (IoT) crowd, how are the driverless vehicle people doing 
with regard to the cyber security of these vehicles. That is, is it conceivable 
that someone may try to hack the truck's operating system and hijack it?

Thanks all,

doug

--

Douglas E Powell

doug...@gmail.com
http://www.linkedin.com/in/dougp01
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Re: [PSES] HDMI questions

[Pawson, James]

Ah, hello 742.5MHz my old friend.

Alfred’s analysis in his email is good especially regarding frame rate. If you 
look in the 1.4 HDMI standard in section 5.1.2 you can see that the “vertical 
blanking” period consists of 45 lines. A breakdown of what’s contained within 
follows below that section. You can conduct further analysis of this period by 
using an FFT function on a high bandwidth digital scope (although you may 
struggle with the lower number of samples available in this target block) to 
narrow in on which part of the signal is causing you issues.

As for the frequency:

1080p/50Hz resolution uses a clock frequency of 148.5MHz. The three data pairs 
frequency is 5 x f_clk = 742.5MHz. Expect to see multiples of the clock at 
445.5, 594 and 891MHz and plenty of emissions above 1GHz at 1485, 2227.5, 
2970MHz, etc.
1080i/50Hz and 720p/50Hz resolution uses clock of 74.25MHz and data of 371.25 
MHz

It is this data fundamental that causes many of the radiated emissions problems 
associated with HDMI.

This can be caused by poor signal integrity, mainly uneven tr/tf within each 
half of the differential pair. Possible solutions involve playing around with 
the pre-emphasis and drive strength register settings within the silicon, 
remembering to verify the signal integrity if you’ve found a combination that 
seems to work.

Inline common mode chokes sometimes help at frequencies above 1GHz but more 
often not at these “lower” frequencies in the HDMI interface.

Your best bet is carefully selecting a HDMI cable that has good shielding 
termination between cable screen and backshell. This is mostly a case of trial 
and error when purchasing from catalogs (forget eBay or Amazon here) or working 
with the cable vendor (e.g. Molex, Amphenol, Palpilot – other reputable cable 
vendors are available) to specify a decent quality cable. Cut open a $1 cable 
from Amazon and marvel at the internal construction!

I hope this helps,
Best of luck
James


From: Brent DeWitt [mailto:bdew...@ix.netcom.com]
Sent: 15 October 2016 23:58
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] HDMI questions

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] Measurement Accuracy

[Pawson, James]

Thanks for the link to that paper Rich, it makes for interesting reading in 
plain English.
James



From: Richard Nute [mailto:ri...@ieee.org]
Sent: 20 September 2016 21:18
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Measurement Accuracy

…

I didn’t know what “uncertainty” is, so I did a Google search and found this 
reference:

https://www.wmo.int/pages/prog/gcos/documents/gruanmanuals/UK_NPL/mgpg11.pdf


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Re: [PSES] capacitive touch equipment

[Pawson, James]

Morning Gary,

In my experience noise resistance will depend on many factors e.g. self vs 
mutual capacitance method, the cap touch device selected, sensor design, etc. 
The major design trade-offs are sensitivity and speed of response vs noise 
resistance and available panel size. Cap touch tends to be as much of a 
mechanical design challenge (in mounting the sensor PCB as close to the touch 
surface as possible and minimising any low permittivity gaps (i.e. air) between 
the sensor and touch object)  as an electronic design challenge.

I've had considerable success using a flexible PCB (not as expensive as I 
expected) and some 3M double sided adhesive tape to make a very compact and 
reasonably robust solution. Various noise protection strategies are available 
from different vendors. Microchip touch solutions use a driven guard plane to 
increase the sensitivity and to reduce the noise susceptibility which yields 
good results. With some crafty sensor design, it could probably perform even 
better. However, you may find a dedicated touch controller (from someone like 
Azoteq for instance) may have better noise resistance. Vendors do seem to be 
quite keen in this field and have many sample / evaluation kits to hand out.

Hope this helps
James


From: Gary McInturff [mailto:gary.mcintu...@esterline.com]
Sent: 30 August 2016 22:04
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] capacitive touch equipment

Does anybody have any experience with us military electromagnetic immunity or 
emissions for P cap front panels. I understand from the water rain side of 
things but haven't yet been involved from emc end. mainly looking for it's a 
big issue or small issue for the p cap itself. Pcbs etc. I'm familiar with mil 
emc testing just not the pcap itself

thanks

Gary McInturff
Reliability/Compliance Engineer










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Re: [PSES] iNARTE EMC accreditation - thoughts?

[Pawson, James]

Hello all,

I've been interested to see the range of comments on this question. Thank you 
all for taking the time to help. I'm going to investigate further!

Regards,
James

_____
From: Pawson, James
Sent: 10 August 2016 17:01
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: iNARTE EMC accreditation - thoughts?


Hello fellow engineers,

With an eye on the future, I am considering taking an iNARTE EMC qualification. 
Specifically, I'm considering one (or possibly both) of these accreditations.

-   iNARTE EMC Design Engineer Certification
-   iNARTE Electromagnetic Compatibility (EMC/EMI) Certification

I'm looking for your advice and experience of

-   Gaining these qualifications
-   Views of the engineering community on the worth of these qualifications
-   Suggestions as to which one of these would be most beneficial for a 
career in EMC either working as a company employee or as a 
contractor/consultant in EMC testing and design

I appreciate these are open questions and I would appreciate any and all 
opinions. If you feel more comfortable replying off list then please do.

Thanks and regards,
James Pawson


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[PSES] iNARTE EMC accreditation - thoughts?

[Pawson, James]

Hello fellow engineers,

With an eye on the future, I am considering taking an iNARTE EMC qualification. 
Specifically, I'm considering one (or possibly both) of these accreditations.

-   iNARTE EMC Design Engineer Certification
-   iNARTE Electromagnetic Compatibility (EMC/EMI) Certification

I'm looking for your advice and experience of

-   Gaining these qualifications
-   Views of the engineering community on the worth of these qualifications
-   Suggestions as to which one of these would be most beneficial for a 
career in EMC either working as a company employee or as a 
contractor/consultant in EMC testing and design

I appreciate these are open questions and I would appreciate any and all 
opinions. If you feel more comfortable replying off list then please do.

Thanks and regards,
James Pawson


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Re: [PSES] SAFETTY FEATURES controlled by ....SOFTWARE

[Pawson, James]

Windows for Submarines
http://www.theregister.co.uk/2008/12/16/windows_for_submarines_rollout/
Good job our nuclear "deterrent" isn't safety critical!


From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com]
Sent: 04 August 2016 19:46
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] SAFETTY FEATURES controlled by SOFTWARE

The Windows licenses prohibit use in safety critical applications.  Wouldn't 
want that BSOD and having to re-boot in order to re-start the airplane engine 
at 10K feet.  Still not a comfortable feeling for the average traveler to see 
that fatal error - reboot screen or what-have you on the seatback entertainment 
monitor while flying on the 777 et. al.

-Dave

From: B Rowland [mailto:bfr...@direct.ca]
Sent: Thursday, August 04, 2016 2:33 PM
To: Nyffenegger, Dave
Cc: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] SAFETTY FEATURES controlled by SOFTWARE

Hi List-colleagues;

I think, if the safety-related functions are life-critical, they need to be 
written in a "provably-correct" language/environment, like ADA, or some 
equivalent. And, of course, that also means that such functionality needs to be 
isolated from software that is NOT provably-correct (is Windows 
"provably-correct" ?)...

In any case, life-critical systems need to be, at least, redundant, with 
fail-safe shutdown if the processes do not agree at timed checkpoints, and also 
have hardware-based watchdog timers (sometimes built-in to the microcontroller, 
itself) to guarantee continued function. Furthermore, it is also typical that 
the software that runs on the redundant processors is written by different 
teams, so that an error in a program on one "side" is not duplicated in the 
other half/third of the redundant CPUs.

Since, as some have pointed out, it is readily-accomplished to have a 
provably-correct hardware implementation of the safety functions that are "at 
the edge" of the system, FPGA's, PALs, etc., with ROM, or 
check-summed-on-load-firmware, are much more reliable

In another discussion that I had, a while back, we even discussed how to ensure 
that the semiconductor devices, at the safety interface, are made 
reliable-enough to allow proper operation, even in the typical fail-short 
conditions. I think that this is why we have relays costing > $1000 used in 
train/subway applications ;-)

Cheers,
Barry Rowland
Muenchen, Bayern




On  04/08/2016, at 18:25 , "Nyffenegger, Dave" 
mailto:dave.nyffeneg...@bhemail.com>> wrote:

Which is essentially what UL 1998 requires for the product design.  I agree 
with keeping software/programmable devices out of the safety business as much 
as possible so you can skip the significant engineering investment required to 
do it properly.

-Dave

From: Carl Newton [mailto:emcl...@gmail.com]
Sent: Thursday, August 04, 2016 10:54 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] SAFETTY FEATURES controlled by SOFTWARE

My experience with UL Medical (as an example) is that their position is that 
software fails 100% of the time from a safety point of view (and I agree with 
that view).  The manufacturer would have to prove to the lab that it is 
fail-safe, which is probably not a desirable task on the part of the designers, 
and may not be possible from a practical point of view.  I've been told that in 
those unusual cases where software/firmware has been allowed as protection 
against hazards is when the software/firmware is completely separated from any 
other system software (standalone) within the hardware architecture so that it 
cannot be corrupted and will have only that one dedicated function.

Carl
On 8/3/2016 10:32 AM, Bolintineanu, Constantin wrote:

Dear Colleagues,

I would like to kindly ask those who have an extensive experience regarding the 
above subject, to share their opinion about the following aspect:

Having a circuit which is charging a battery, and having it controlled and 
protected  by SOFTWARE ONLY from the point of view of CHARGING , DISCHARGING, 
OVERCHARGING,

1. How do you think that SINGLE FAULT CONDITIONS shall be applied? (without 
SOFTWARE working at all? Or by providing a fault on the component where the 
SOFTWARE is stored? OR BOTH
2. Which conditions do you think that shall be imposed to the software and/or 
to the memory in which it is stored?

Any other suggestions/observations/comments are more than welcome.

Sincerely,

Constantin Bolintineanu P.Eng.




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Re: [PSES] Handheld or portable voltmeter/ammeter with built-in and adjustable limit function with audible alarm

[Pawson, James]

Hi Ken,

I built a device to do this for monitoring audio outputs from our products when 
performing immunity tests for the EN55020 Broadcast Receiver Immunity standard, 
measuring 1kHz breakthrough. 6 input channels with a 1kHz active bandpass 
filter on each, output rectified and fed into a comparator, reference level set 
appropriately (half the peak audio level IIRC). Output of comparator into a 
series of LEDs and diode OR'd into a very loud buzzer. All wrapped up in a die 
cast aluminium enclosure with very robust knobs to make it proof against 
regular lab use.

It was most amusing listening to our technician performing the test; the sound 
of the buzzer shortly followed by an even louder annoyed huff as he got up from 
his chair to go and see what the problem was :)

James



From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: 30 May 2016 16:57
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Handheld or portable voltmeter/ammeter with built-in and 
adjustable limit function with audible alarm

For an EMI test, I need to monitor direct current and set a limit above which I 
get an audible alarm.  I don't want to constantly have to watch an 
ammeter/voltmeter while also operating the susceptibility equipment. I also 
don't want to have to connect a DVM to a PC; I want the limit setting function 
to be self-contained.  Seems as if there ought to be such a device, but I can't 
find it. Doesn't have to be an ammeter per se; if it can measure dc millivolts, 
I can use a current shunt.

Thank you,

Ken Javor
Phone: (256) 650-5261
-


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Re: [PSES] Question regarding clock jitter specification

[Pawson, James]

(Re-sending)

Hi Ken,

To take HDMI as an example, it defines a transfer function for the clock 
recovery PLL with a cut off above 4MHz. My understanding is that this is the 
loop response of the receivers clock recovery PLL meaning that jitter 
frequencies below this cut off are tracked but higher ones are not. Other 
standards will presumably define their own PLL response.

Hope this helps
James

From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: 25 May 2016 23:54
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] Question regarding clock jitter specification

The cited article was very interesting as to how to measure Jitter, but it did 
not answer the questions I posed as to how clock jitter is spec'd and how fast 
it changes (analogous to fm deviation and rate of deviation).

This is not CISPR, it is measurements in band to specific radios with specific 
channel bandwidths, and the issue is to properly specify a measurement BW, and 
what happens when the measurement BW is improperly specified (measurement BW < 
radio channel BW).

Ken Javor
Phone: (256) 650-5261
____
From: "Pawson, James" 
mailto:james.paw...@echostar.com>>
Reply-To: "Pawson, James" 
mailto:james.paw...@echostar.com>>
Date: Wed, 25 May 2016 09:42:55 +
To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG>>
Conversation: Question regarding clock jitter specification
Subject: Re: [PSES] Question regarding clock jitter specification

Ken,

Jitter can be a very complicated subject; we once received a detailed and 
complex presentation from LeCroy (now Teledyne) on the different types of 
jitter and how you could separate them out from each other e.g. random jitter, 
deterministic jitter, etc. It had more pictures and detail than this document - 
http://cdn.teledynelecroy.com/files/whitepapers/wp_jittermeasurement_in_serialdatasignals.pdf
 - but it gives you the flavour.

Generally jitter seems to be defined as a maximum deviation from an ideal clock 
rate (e.g. 0.25 x T_bit for HDMI). The ideal clock could be either a recovered 
clock in the case of a serial link (like HDMI or SATA) or a clock that is 
transmitted in parallel to the signal (like PCIe). Introduce spread spectrum 
clocking in there and measurement becomes even more interesting!

For the frequencies that you refer to, I believe CISPR defines a measurement 
bandwidth of 1MHz so I'm not sure why someone would me measuring with such a 
RBW unless it was specifically mentioned in a standard. You might hope that 
excessive jitter would make these higher harmonics a little lower in amplitude 
;)

James


From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: 25 May 2016 04:20
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: [PSES] Question regarding clock jitter specification

What is a typical clock jitter specification? Is it given as a percentage of 
clock period? If not, how?  Given some maximum jitter spec, how quickly does 
the clock period change? Can it go from no jitter to maximum deviation in one 
clock cycle? If so, is that typical? Or is it more typical to stay much closer 
to nominal than the jitter spec allows for many clock cycles, and then slowly 
deviate?

These questions are asked not from a signal integrity vantage point, but rather 
that of EMC. In particular, I am concerned about people using very narrow 
measurement BWs to measure radiated emissions in microwave bands where the 
measurement is that of a clock harmonic, and thus the spreading of the clock 
jitter residual frequency modulation at the fundamental by the harmonic order.

So for instance, if someone uses a 1 kHz BW at 10 GHz and expects to accurately 
measure the full value of a cw tone that is the harmonic of a lower frequency 
clock, the implication is that the jitter is less than 1e-7 of the clock period 
which will be much less than 1 ps even with a 10 MHz clock.  If the jitter 
exceeds this value and actual radio protected by the RE measurement has a 
larger BW than that used in the RE measurement, then if the harmonic is quickly 
wandering in and out of the measurement pass band, it will be averaged in a way 
not representative of what the actual radio would see.

Hence, the questions.

Thank you,

Ken Javor
Phone: (256) 650-5261
-

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Re: [PSES] Question regarding clock jitter specification

[Pawson, James]

Ken,

Jitter can be a very complicated subject; we once received a detailed and 
complex presentation from LeCroy (now Teledyne) on the different types of 
jitter and how you could separate them out from each other e.g. random jitter, 
deterministic jitter, etc. It had more pictures and detail than this document - 
http://cdn.teledynelecroy.com/files/whitepapers/wp_jittermeasurement_in_serialdatasignals.pdf
 - but it gives you the flavour.

Generally jitter seems to be defined as a maximum deviation from an ideal clock 
rate (e.g. 0.25 x T_bit for HDMI). The ideal clock could be either a recovered 
clock in the case of a serial link (like HDMI or SATA) or a clock that is 
transmitted in parallel to the signal (like PCIe). Introduce spread spectrum 
clocking in there and measurement becomes even more interesting!

For the frequencies that you refer to, I believe CISPR defines a measurement 
bandwidth of 1MHz so I'm not sure why someone would me measuring with such a 
RBW unless it was specifically mentioned in a standard. You might hope that 
excessive jitter would make these higher harmonics a little lower in amplitude 
;)

James

From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: 25 May 2016 04:20
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Question regarding clock jitter specification

What is a typical clock jitter specification? Is it given as a percentage of 
clock period? If not, how?  Given some maximum jitter spec, how quickly does 
the clock period change? Can it go from no jitter to maximum deviation in one 
clock cycle? If so, is that typical? Or is it more typical to stay much closer 
to nominal than the jitter spec allows for many clock cycles, and then slowly 
deviate?

These questions are asked not from a signal integrity vantage point, but rather 
that of EMC. In particular, I am concerned about people using very narrow 
measurement BWs to measure radiated emissions in microwave bands where the 
measurement is that of a clock harmonic, and thus the spreading of the clock 
jitter residual frequency modulation at the fundamental by the harmonic order.

So for instance, if someone uses a 1 kHz BW at 10 GHz and expects to accurately 
measure the full value of a cw tone that is the harmonic of a lower frequency 
clock, the implication is that the jitter is less than 1e-7 of the clock period 
which will be much less than 1 ps even with a 10 MHz clock.  If the jitter 
exceeds this value and actual radio protected by the RE measurement has a 
larger BW than that used in the RE measurement, then if the harmonic is quickly 
wandering in and out of the measurement pass band, it will be averaged in a way 
not representative of what the actual radio would see.

Hence, the questions.

Thank you,

Ken Javor
Phone: (256) 650-5261
-


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Re: [PSES] Anechoic Chamber Questions

[Pawson, James]

Many thanks to all who replied on the subject.

I have made some measurements in our chamber using a broadband noise source at 
different positions relative to the receive antenna. The aim was to 
characterise the chamber performance and check for any reflections or non-ideal 
performance. There is a summary of my results here:

https://drive.google.com/open?id=0B8tV5DDyzNucQW9uLThYLVF6MXM

My conclusion is, at certain frequencies (e.g. 600MHz on last slide), there is 
an unacceptable amount of reflection in our chamber that appears to be partly 
caused by lower absorption from the ceiling and EUT wall.

Any criticisms of the work or methods used or thoughts on what else I could try 
to establish if this is the case would be most welcomed.

Many thanks
James

_
From: Pawson, James
Sent: 29 April 2016 08:14
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Anechoic Chamber Questions


Hello all,

I have some questions about anechoic chambers that I need some help with and 
I'm sure there is some expertise in this group that can help.

1)  My understanding is that an anechoic chamber is meant to simulate a 
reflection-less, free space environment. Therefore if you move a source towards 
/ away from the antenna, the signal level should follow the inverse square law 
- correct?

2)  When comparing absorber types (hybrid + ferrite tile vs. foam absorber) 
the return loss characteristic gives the amount of absorption at a particular 
frequency - correct?

3)  If I wanted to compare effectiveness of foam absorber with hybrid + 
tile absorber is it just a case of adding the return loss of the hybrid to the 
return loss of the tile to achieve a final figure? My understanding is that the 
hybrid helps match the wave impedance from free space to that of the tile. Is 
the return loss of hybrid + tiles _together_ greater than the individual return 
losses of the separate components? Manufacturers that I've looked at list the 
data separately.

4)  I have been told that the distance between absorber and a reflective 
metal backing is important for ensuring that the returning wave is in 
anti-phase (or at least as much as possible) with the incoming signal. However 
information on acceptable limits for this distance seems sporadic or in 
rarefied scientific papers behind paywalls. Does anyone have any info or 
experience on this point?

Many thanks for your time, I'm trying to get a handle on our chamber's 
performance and any answers will help.

Regards,
James



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[PSES] Anechoic Chamber Questions

[Pawson, James]

Hello all,

I have some questions about anechoic chambers that I need some help with and 
I'm sure there is some expertise in this group that can help.

1)  My understanding is that an anechoic chamber is meant to simulate a 
reflection-less, free space environment. Therefore if you move a source towards 
/ away from the antenna, the signal level should follow the inverse square law 
- correct?

2)  When comparing absorber types (hybrid + ferrite tile vs. foam absorber) 
the return loss characteristic gives the amount of absorption at a particular 
frequency - correct?

3)  If I wanted to compare effectiveness of foam absorber with hybrid + 
tile absorber is it just a case of adding the return loss of the hybrid to the 
return loss of the tile to achieve a final figure? My understanding is that the 
hybrid helps match the wave impedance from free space to that of the tile. Is 
the return loss of hybrid + tiles _together_ greater than the individual return 
losses of the separate components? Manufacturers that I've looked at list the 
data separately.

4)  I have been told that the distance between absorber and a reflective 
metal backing is important for ensuring that the returning wave is in 
anti-phase (or at least as much as possible) with the incoming signal. However 
information on acceptable limits for this distance seems sporadic or in 
rarefied scientific papers behind paywalls. Does anyone have any info or 
experience on this point?

Many thanks for your time, I'm trying to get a handle on our chamber's 
performance and any answers will help.

Regards,
James



-

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discussion list. To post a message to the list, send your e-mail to 


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Re: [PSES] Commom mode current vs. differential mode current and LISN

[Pawson, James]

In relation to this discussion, what is the significance of the vertical lines 
either side of the |L| or |N|?
Google doesn't recognise it as a searchable term, possibly thinks it is a 
logical OR symbol?
Thanks
James


From: Elliott Martinson [mailto:elliott.martin...@etcconnect.com]
Sent: 30 March 2016 22:05
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Commom mode current vs. differential mode current and LISN

Sorry if this is being over exhausted.

I don't think I'm straying far from the real-world here. Let's say for sake of 
argument, CM and DM currents from a single source are necessarily 100% in 
phase, ignoring whether it's true/false. In a real device of moderate 
complexity, I don't see any reason why there can't be more than one independent 
source of noise at a particular frequency. Whether differential-mode or 
common-mode noise dominates one source, the dominant modes of the other sources 
don't follow. They also aren't necessarily in phase with each other (they 
aren't necessarily out of phase either). There's an entire range of 
possibilities, all affecting the proportion of DM and CM noise required to 
account for measuring |L| = |N| at a particular frequency, meaning it could be 
all DM and no CM, it could be all CM and no DM, it could be equal parts both, 
60/40, or anything else between. The whole point of this hypothetical 
measurement is that we don't know enough about the noise source(s) to begin 
with, so the assumption of a single source could be a bit of a leap, unless we 
do in fact know our source for sure (such as a switching circuit).

Personally, I disagree with stating a rule-whose truth depends on a number of 
assumptions-as fact without acknowledging and justifying those assumptions. 
I've read an EMC textbook by each of the authors to whom you referred (great 
books, btw), and they do argue that if |L| = |N| it follows that one must 
dominate. Neither acknowledges the assumption of either 0 or 180 degree phase 
difference between the two. The derived equations may be true, but the 
interpretation of their implications ignores the fact that a current can have a 
complex amplitude (i.e. phase shift).

The rule may just be stated backwards, mixing what follows from what. It's not 
that if |L| and |N| are similar, either DM or CM must dominate. Rather, if 
either DM or CM dominates, |L| and |N| will be similar! ...Besides, If |L| and 
|N| can be measured individually, that same current probe can also be used to 
measure |L+N| and |L-N| directly. No assumptions necessary ;)


ALSO,
How common-mode currents arise and predicting their behavior accurately isn't 
always very easy to wrap my head around, so correct me if I'm completely wrong 
here:
Common-impedance coupling through parasitic resistance from a DM current leads 
to a common-mode voltage exactly in phase with that DM current. That CM voltage 
can then leak through stray capacitance as a CM current that's out of phase 
with the DM current/CM voltage.

The above effect, if correct, is very unlikely to produce CM current of any 
significance, so the DM current will almost certainly dominate. It's not an 
example of how |L| can equal |N| without CM or DM dominating but rather an 
example of CM current out of phase with DM current.


Elliott Martinson
Product Assurance Specialist I
Electronic Theatre Controls
3031 N PLEASANT VIEW RD
MIDDLETON WI 53562-4809
Work: 608.824.5696 / Cell: 608.209.9897
elliott.martin...@etcconnect.com

From: John Woodgate [mailto:jmw1...@btinternet.com]
Sent: Wednesday, March 30, 2016 9:09 AM
To: Elliott Martinson 
mailto:elliott.martin...@etcconnect.com>>
Subject: RE: [PSES] Commom mode current vs. differential mode current and LISN

I wouldn't want to conjecture whether something *might* happen. Real-world 
issues are enough, I think. You could look at the textbooks by Henry Ott and 
Clayton R Paul for more general studies.

With best wishes OOO - Own Opinions Only 
www.jmwa.demon.co.uk
J M Woodgate and Associates Rayleigh England

From: Elliott Martinson [mailto:elliott.martin...@etcconnect.com]
Sent: Wednesday, March 30, 2016 3:01 PM
To: John Woodgate mailto:jmw1...@btinternet.com>>
Subject: RE: [PSES] Commom mode current vs. differential mode current and LISN

Possibly. I am certainly no expert-in fact I only just found out EMC exists 
shortly before getting my most recent job last July.

Could common-impedance coupling from a purely capacitive or inductive impedance 
in the return cause common-mode noise that's exactly out of phase with the 
differential-mode noise? That sounds really unlikely at low frequency where 
resistance is significant, but at high frequency, maybe on a thin return 
conductor?

Elliott Martinson
Product Assurance Specialist I
Electronic Theatre Controls
3031 N PLEASANT VIEW RD
MIDDLETON WI 53562-4809
Work: 608.824.5696 / Cell: 608.209.9897
elliott.martin...@etcconnect.com

From: John Woodgate [mailto:jmw1...@btinternet.com]
Sent: W

Re: [PSES] NEBS GR1089 for Remote Radio Heads

[Pawson, James]

Tablestakes.
http://annoyingpr.tumblr.com/post/13776378688/table-stakes


-Original Message-
From: Marko Radojicic [mailto:052300254e41-dmarc-requ...@ieee.org] 
Sent: 11 March 2016 01:02
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] NEBS GR1089 for Remote Radio Heads

NEBS typically tablestakes for ATT and Verizon business.

For outdoor equipment, applicable environmental standard is GR-3108, probably 
Class 4.

Sent from my mobile
Please excuse brevity & grammar 

> On Mar 10, 2016, at 3:19 PM, Brian O'Connell  wrote:
> 
> Joe is probably the subject-matter expert for this stuff. My NEBS experience 
> is based on the grand total of ONE project. Depends on the carrier/provider. 
> Some service providers now use their own (internal) version of GR-core 
> standards. While original NEBS not scoped for pole-mounted stuff, the newer 
> stuff found in GR487 and NEMA IP have been (historically) cited by and are 
> oft adopted as 'code' by various local governmental bodies in North America, 
> so many cabinet and equipment makers do NEBS and NEMA certifications as pro 
> forma.
> 
> Brian
> 
> From: Joe Randolph [mailto:j...@randolph-telecom.com]
> Sent: Thursday, March 10, 2016 3:06 PM
> To: EMC-PSTC@LISTSERV.IEEE.ORG
> Subject: Re: [PSES] NEBS GR1089 for Remote Radio Heads
> 
> Hi Charlie:
> 
> If the equipment will be used by a major US carrier in their own network, I 
> think NEBS GR-1089 compliance is likely to be required by the carrier.  
> 
> As you probably know, the NEBS requirements are industry standards rather 
> than regulatory requirements, so NEBS compliance is not required by law.
> 
> However, most carriers place great importance on the reliability of the 
> equipment used in their network, and compliance with the NEBS requirements 
> gives them some assurance that the product will hold up well in the intended 
> environment.  For example, the lightning immunity requirements in GR-1089 are 
> generally the most stringent lightning requirements worldwide.
> 
> In the end, though, whether NEBS compliance is required, or what subset of 
> the NEBS requirements will be required, gets down to a negotiation between 
> the manufacturer and the carrier.
> 
> 
> Joe Randolph
> Telecom Design Consultant
> Randolph Telecom, Inc.
> 781-721-2848 (USA)
> j...@randolph-telecom.com
> http://www.randolph-telecom.com
> 
> From: Charlie Blackham [mailto:char...@sulisconsultants.com]
> Sent: Thursday, March 10, 2016 4:58 PM
> To: EMC-PSTC@LISTSERV.IEEE.ORG
> Subject: [PSES] NEBS GR1089 for Remote Radio Heads
> 
> All
> 
> Client makes outdoor, pole mounted, LTE radio heads and they are receiving a 
> number of customer enquiries regarding status of NEBS compliance.
> Does anyone have experience of whether the major US operators require full 
> NEBS EMC compliance for outdoor, data equipment - or is it more of a "nice to 
> have"?
> 
> Regards
> Charlie
> 
> Charlie Blackham
> Sulis Consultants Ltd
> Tel: +44 (0)7946 624317
> LinkedIn: uk.linkedin.com/in/charlieblackham/
> Web: www.sulisconsultants.com
> Registered in England and Wales, number 05466247
> 
> -
> 
> This message is from the IEEE Product Safety Engineering Society 
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Re: [PSES] Source for Quality Video Cables

[Pawson, James]

Brian,

I feel your pain and share Rodney's opinions on HDMI cables which are my man 
bugbear. Depending on how many you purchase a year or at a time you may well 
find some cable companies willing to work with you.

James

-Original Message-
From: Kunde, Brian [mailto:brian_ku...@lecotc.com] 
Sent: 02 March 2016 15:43
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Source for Quality Video Cables

We are in need of a reasonably priced source for quality and reliable video 
cables; specifically a Single Link DVI Male to Male in a variety of lengths. In 
one application we would prefer one end of the cable to be a right angle.

We have received and tested numerous over the counter DVI cables; some test 
great, some are absolutely horrible (Radiated Emissions Test).  So we started 
purchasing the ones that tested good only to find out later that they do not 
hold up. Flexing the cable and connector a few times will break loose the 
Backshell to Cable shield connection.

So now, before we test, we are cutting open the over-mold and examining how the 
Back-shell to cable shield connection is made. What an eye opener. Some cables 
just use the over-mold to hold it all together. Most cables, if you flex the 
cable 2 or 3 times you can completely  pull the cable shield away from the 
back-shell if it even has a backshell. One cable we cut open, they just wrap 
the ends with coper tape (no solder) and then overmold it.

We are also finding that even cables made by the same company are made 
differently. How this termination is done on a 6 ft cable is different than a 
10 ft cable from the same company. No consistency. This is becoming a nightmare.

I was hoping someone could help me out and point me in the right direction.  
Our company is not big enough to influence a cable manufacture directly (we 
purchase through distribution), have such a cable custom made, and it would be 
very expensive to bring in the tools to build it ourselves.

Thanks for any suggestions or advice.

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] Reliable means to attach thermocouple to object

[Pawson, James]

As a young and naïve student I once used hot melt glue.

There's a clue in the name kids!

James



-Original Message-
From: Scott Xe [mailto:scott...@gmail.com] 
Sent: 26 February 2016 16:53
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Reliable means to attach thermocouple to object

I used to attach thermocouple to the object under temperature rise test using 
Kapton tape.  Currently I looked at an SMPS that is operating at a temperature 
of 120 degC under an ambient temperature of 20 degC.  The tape seems not very 
reliable and rigid enough for long period of testing.  Is there any other more 
suitable means to attach the thermocouple to such high temperature point of 
interest?

The spec quotes the max temperature of 150 degC.  Is it normal for the 
rectifier to have such high operating temperature?

Thanks and regards,

Scott  

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Re: [PSES] Energy in certain items

[Pawson, James]

About 2.8x10^17 Joules for a gallon of petrol using E = mc^2 
This is why I'm always disappointed by the mpg of my car
James


-Original Message-
From: Macy [mailto:m...@basicisp.net] 
Sent: 19 February 2016 17:59
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Energy in certain items

Does anyone know the energy [joules] in a standard stick of dynamite, or a 
gallon of gasoline?
 

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Re: [PSES] Unexplained High Fallout of Power Supplies

[Pawson, James]

Hi Brian,

Is the furnace type common to all the failed pieces of equipment? If not 
common, similar?

Reading on with interest
James

 

-Original Message-
From: Kunde, Brian [mailto:brian_ku...@lecotc.com] 
Sent: 17 September 2015 14:37
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Unexplained High Fallout of Power Supplies

Bob and all.

Good question. Before I answer your questions, let me describe the typical 
architecture of the products that we make.

Our instruments (laboratory equipment) are single phase 230VAC 50/60hz which 
powers two separate internal circuits; one being a relatively low current 
electronics powered by a purchased over-the-shelf 24Vdc power supply, and 
second, a high current furnace of some type; inductive, electrode, resistive 
heating elements, etc.. Because of the high overall current of the instruments, 
typically between 30A and 50A, the instrument is plugged into a high current 
branch circuit with a huge high current line filter. Internally, we usually 
have a smaller supplementary over-current protector (5, 10 or 15 amp) driving 
the lower current non-furnace electronics such as the dc power supply, cooling 
fans and blowers, etc..

The issues we are having are with these purchased power supplies blowing up. 
And because we pre-test power supplies and our finished products so extensively 
and we are not able to cause a power supply failure with the same damage 
pattern as we are seeing in the field, we believe that in the real world our 
products are seeing some kind of condition that we are not able to simulate in 
our EMC Lab. Identifying and understanding such conditions is our goal at this 
time.

We use no additional inrush limiting other that what is built into the power 
supplies themselves. Other than a thermistor of some kind, how can the inrush 
be limited?

We have also seen on several occasions in the field where a power supply will 
blow up in one instrument which causes the power supply in a nearby instrument 
to also fail.

Two weeks ago we had an "event" occur right here at our own campus in our 
Application Lab where 40-50 instruments of different models and ages are being 
used daily to develop test methods. An instrument was power on but was not 
running an analysis (high current furnace wasn't running in what we call 
Standby-mode). BAM!! The 24Vdc power supply blew up. We sent two R&D engineers 
who have been working on our fallout problem in the field to investigate. They 
found the power supply had failed in the same way as those in the field. No 
other failed component in the instrument was found. The power supply was 
replaced and the instrument was once again functional. AS THE Engineers turned 
to walk back to their office, BAM!! The power supply blew up in the instrument 
installed NEXT to the one they just repaired. This second instrument is a 
different model with a different manufacturer of power supply. An AC Power Line 
monitor/analyzer was installed on the AC Mains circuit and has been c!
 hecked every morning since. No unusual transients or power dropouts have been 
detected.

This lab area has surge protection, so again, we believe the problem is some 
kind of low voltage transient, voltage dropout, or waveform distortion that we 
have been unable to detect and simulate.

Thanks to all.

The Other Brian

-Original Message-
From: Bob LaFrance [mailto:b...@creare.com]
Sent: Thursday, September 17, 2015 8:46 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Unexplained High Fallout of Power Supplies

I am curious to what you are using for inrush limiting.  Sorry if you already 
told us but I missed that.

Regards,
Bob LaFrance
N9NEO
Design Engineer
Creare Inc.
16 Great Hollow Road
Hanover, NH
603-640-2539


-Original Message-
From: CR [mailto:k...@earthlink.net]
Sent: Wednesday, September 16, 2015 2:56 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Unexplained High Fallout of Power Supplies

On 9/15/2015 4:53 PM, Kunde, Brian wrote:
> we have not been able to find the reason for the fallout. The power 
> supplies have all shown arc damage to the AC front end, signs of 
> arcing and traces burned or vaporized, blown fuses, and shorted FETs 
> and/or Rectifiers. These failures have occurred on several different 
> locations, on different power supply models, different manufactures 
> and on different instruments. Some instruments have been in service 
> for years; some for only a few weeks before they fail. Some 
> instruments even have surge suppression modules installed and though 
> the power supplies fail the surge modules tested out fine. The 
> failures did not occur during any known lightning storm or any other 
> known transient.
Brian,

The circumstances you describe -- arcing with no external transient seen
-- point to an on-board occurrence, not an external one.  I'd suspect (in no 
particular order and on little information -- heh) ) PWB material with 
insufficient dielectric withstand, 

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

[Pawson, James]

Hi Ken,

Assuming your problem is radiated emissions I guess it depends at what 
frequencies your problem emissions are at. If they are harmonics of the USB 
data then it could be poor signal balance (a common mode choke could help) or 
perhaps poor cable shielding (very likely with USB). If they are not part of 
the harmonic series of the USB signalling then they could be coming from other 
PCB circuit areas.

Regards,
James

From: Ken Wyatt [mailto:k...@emc-seminars.com]
Sent: 10 September 2015 20:03
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! | Web Site 
| Blog
The EMC Blog (EDN)
Subscribe to Newsletter
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Re: [PSES] HDMI extension cable recommendation?

[Pawson, James]

Hi Cortland,

I'm not a Linked In user so feel free to repost if you think it has merit.

Regards,
James

-Original Message-
From: CR [mailto:k...@earthlink.net] 
Sent: 25 August 2015 11:03
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] HDMI extension cable recommendation?

On 8/25/2015 3:56 AM, Pawson, James wrote:
> In my experience from sourcing and testing many standard HDMI cables it is 
> very difficult to get a good quality shielded cable without working closely 
> with the vendors.

James,

You'll likely get some other "been there, got the Tee shirt" replies beside 
mine. Could you re-post the comment on one of LinkedIn's EMC 
groups? Would you mind if *I* did?   The ARRL EMC group probably need a 
heads-up, too, and maybe Electronic Design, et al..  Companies have short 
memories.

Back in 1986 or so, my brother's VERY high-resolution B&W monitor was 
interfering with his neighbors television reception on the18th floor of a 
Boston MA building. Considering that the transmitting antenna was a few miles 
away and line-of-sight, it had to have been really, really bad. I was able to 
fix that with an external 360 degree shield over the cable, tightly held to the 
EMC backshells with cable ties.  A few years later, At Tandy Computers, I 
tested a 3rd Party TV tuner card when the video cable provided with it made a 
(formerly) compliant computer fail Part 15 -- and only when the tuner function 
was off; somebody had missed that.  Fun times.

Cheers,

Cortland Richmond
KA5S

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Re: [PSES] HDMI extension cable recommendation?

[Pawson, James]

Hi Brent,

In my experience from sourcing and testing many standard HDMI cables it is very 
difficult to get a good quality shielded cable without working closely with the 
vendors. At the very least a copper foil backshell with good solder termination 
should be specified but better performance can be had with an all metal two 
part backshell.

Most of the products sold through Amazon, eBay, etc. are generally unshielded 
or poorly shielded. I even tested some expensive super Hi-Fi HDMI cables that 
retailed for $30 for 1m and they were just as bad as the rest. Ones with 
moulded "ferrites" on them were often found to perform the worst.

I would try and find parts from a reputable manufacturer, perhaps Molex, 
Amphenol and try them. Be prepared to buy and test several samples before you 
find The One.

I hope this helps,
James




-Original Message-
From: Brent DeWitt [mailto:bdew...@ix.netcom.com] 
Sent: 24 August 2015 16:49
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] HDMI extension cable recommendation?

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

[Pawson, James]

Very helpful, thanks Brent!

From: Brent DeWitt [mailto:bdew...@ix.netcom.com]
Sent: 08 August 2015 01:19
To: Pawson, James; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: [PSES] Calculating Reflection Angles on OATS/SAC

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<mailto: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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List rules: http://www.ieee-ps

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

[Pawson, James]

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
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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discussion list. To post a message to the list, send your e-mail to 


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[PSES] Calculating Reflection Angles on OATS/SAC

[Pawson, James]

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


-

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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Re: [PSES] Radiated Immunity at 1meter distance

[Pawson, James]

Additional thought: near/far field distances would also have to be considered.

-Original Message-
From: Pawson, James 
Sent: 11 May 2015 09:19
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Radiated Immunity at 1meter distance

Hi Brian,

An interesting problem. I suppose that you could perform the test at any 
distance you wanted provided you correctly calibrated at the UFA plane. This 
means you could get the best of both worlds in terms of UFA size and maximum 
field strength.

Regards,
James


-Original Message-
From: Kunde, Brian [mailto:brian_ku...@lecotc.com]
Sent: 08 May 2015 20:56
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Radiated Immunity at 1meter distance

With the release of the 4th edition of IEC60601, we are being asked if we can 
hit 28V/m for Radiated Immunity on the list of bands/frequency called out in 
Table 9. In our current test setup in a large chamber setup in a 3 meter FAR, 
we can barely hit 18 V/m CW at some frequencies. Not sure about these Wireless 
frequencies until we try. There is a note at the bottom of table 9 which states 
that we can test at a 1 meter distance per IEC 61000-4-3, which should increase 
power but wouldn't this also quite drastically narrow the size of the UFA?

I'm sure I can calibrate a 0.5m x 0.5m window but the standard implies that the 
Independent Window Method is only allowed for frequencies above 1Ghz. I use a 
large log antenna below 1Ghz and since I've never tried I'm not sure if the 
beam width limits the size of the UFA at a 1 meter distance.

Done anyone have experience with this and can give me some pointers before I 
start wasting my time?

I assume at a 1 meter distance, my UFA would be much smaller. How would you 
recommend I perform the calibration test. In one example, the EUT will be floor 
standing yet over 2 meters in length. We have to move the EUT to test a section 
of it as a time as it is.

The Window Method also wants you to position the transmit antenna in the center 
of the Window, but at frequencies below 1Ghz, the radials on my log antenna are 
so long I cannot lower the antenna to 1.05m off the floor without the longer 
radials getting too close to the floor.

Any help or advice would be helpful.

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] Radiated Immunity at 1meter distance

[Pawson, James]

Hi Brian,

An interesting problem. I suppose that you could perform the test at any 
distance you wanted provided you correctly calibrated at the UFA plane. This 
means you could get the best of both worlds in terms of UFA size and maximum 
field strength.

Regards,
James


-Original Message-
From: Kunde, Brian [mailto:brian_ku...@lecotc.com] 
Sent: 08 May 2015 20:56
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Radiated Immunity at 1meter distance

With the release of the 4th edition of IEC60601, we are being asked if we can 
hit 28V/m for Radiated Immunity on the list of bands/frequency called out in 
Table 9. In our current test setup in a large chamber setup in a 3 meter FAR, 
we can barely hit 18 V/m CW at some frequencies. Not sure about these Wireless 
frequencies until we try. There is a note at the bottom of table 9 which states 
that we can test at a 1 meter distance per IEC 61000-4-3, which should increase 
power but wouldn't this also quite drastically narrow the size of the UFA?

I'm sure I can calibrate a 0.5m x 0.5m window but the standard implies that the 
Independent Window Method is only allowed for frequencies above 1Ghz. I use a 
large log antenna below 1Ghz and since I've never tried I'm not sure if the 
beam width limits the size of the UFA at a 1 meter distance.

Done anyone have experience with this and can give me some pointers before I 
start wasting my time?

I assume at a 1 meter distance, my UFA would be much smaller. How would you 
recommend I perform the calibration test. In one example, the EUT will be floor 
standing yet over 2 meters in length. We have to move the EUT to test a section 
of it as a time as it is.

The Window Method also wants you to position the transmit antenna in the center 
of the Window, but at frequencies below 1Ghz, the radials on my log antenna are 
so long I cannot lower the antenna to 1.05m off the floor without the longer 
radials getting too close to the floor.

Any help or advice would be helpful.

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] Quasi Peak - Length of Measurement Time for Final Spot Measurement?

[Pawson, James]

Thank you to everyone who responded and clarified the issue, it is much 
appreciated.
Regards,
James


From: Pawson, James
Sent: 26 March 2015 15:02
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Quasi Peak - Length of Measurement Time for Final Spot 
Measurement?

Dear group,

When measuring emissions using a Quasi Peak detector are there any regulations 
or guidance concerning the amount of time one should dwell on a single 
frequency for a measurement?

I know it depends on the nature of the signal. In this case, the signal of 
interest results in a burst of emissions of a high duty cycle followed by a 
long period (i.e. several minutes) of low duty cycle activity. If I use a QP 
detector and measure for 1 second just as the burst happens then I would get a 
high QP reading. If I measure in the steady state period I would get a lower QP 
reading.

In this case, knowing the signals involves, would the intention to be to measure

1.   one full representative cycle of emissions i.e. the initial burst and 
the low duty period after
2.   during the maximum duty cycle only
3.   during the steady state only

I can imagine that the measurement difference between 1) and 3) in this case 
would be small as the level measured during the high duty period would have had 
time to decay down to the same level as the steady state due to the QP time 
constant.

I'm asking this question in the context of both EN 55022 and FCC 15.

Googling for "quasi peak measurement time" and similar phrases is not proving 
helpful

Many thanks
James Pawson

-


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[PSES] Quasi Peak - Length of Measurement Time for Final Spot Measurement?

[Pawson, James]

Dear group,

When measuring emissions using a Quasi Peak detector are there any regulations 
or guidance concerning the amount of time one should dwell on a single 
frequency for a measurement?

I know it depends on the nature of the signal. In this case, the signal of 
interest results in a burst of emissions of a high duty cycle followed by a 
long period (i.e. several minutes) of low duty cycle activity. If I use a QP 
detector and measure for 1 second just as the burst happens then I would get a 
high QP reading. If I measure in the steady state period I would get a lower QP 
reading.

In this case, knowing the signals involves, would the intention to be to measure

1)  one full representative cycle of emissions i.e. the initial burst and 
the low duty period after
2)  during the maximum duty cycle only
3)  during the steady state only

I can imagine that the measurement difference between 1) and 3) in this case 
would be small as the level measured during the high duty period would have had 
time to decay down to the same level as the steady state due to the QP time 
constant.

I'm asking this question in the context of both EN 55022 and FCC 15.

Googling for "quasi peak measurement time" and similar phrases is not proving 
helpful

Many thanks
James Pawson


-

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discussion list. To post a message to the list, send your e-mail to 


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Re: [PSES] USB and radiated emission issues

[Pawson, James]

Hi Amund, a quick brain dump for you


If the emissions are caused by imbalance in the differential signal then a 
Common Mode Choke (CMC) will probably help. Pick one with a good impedance at 
the frequency of interest, 480MHz in this case but you can also expect to see 
emissions at 960MHz and possibly 240MHz as well.

The two main performance graphs are common mode impedance (higher is better) 
and differential mode impedance / insertion loss (lower is better) against 
frequency.

There are wirewound and multilayer ceramic  CMCs made by Murata, Laird, Wurth, 
TDK and probably others. The datasheet generally states if the part is suitable 
for USB 2.0. Ceramic parts usually give better high frequency performance from 
the datasheets I've looked at but are slightly more expensive.

I've seen some manufacturers with combination ESD protection and CMC and some 
with CMC built into the USB connector.

You'll obviously need to measure signal integrity before and after adding the 
chokes to ensure your eye diagram looks OK.


Hope this helps
James


From: Amund Westin [mailto:am...@westin-emission.no]
Sent: 20 March 2015 12:10
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] USB and radiated emission issues

Got some serious radiated emission issues from a USB 2.0 stick (high-speed 
480Mb/sec).
Spectrum shows the 480MHz way over the EN55022 limit line.

We've been told to implement a common mode choke between the USB IC and the 
input/output port. That means on the D+ and D- transmission lines.
http://www.coilcraft.com/0805usb.cfm

Anybody who have experience with such design?


#Amund


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[PSES] Wanted: Screend Room (UK)

[Pawson, James]

Hi all,

We are in the market for a second hand screened room in the UK.

If anyone knows of any being sold please could they get in touch?

Many thanks,

James Pawson
Leading EMC Engineer
EchoStar


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Re: [PSES] CE-magazine

[Pawson, James]

That's the problem with acronyms and abbreviations, they can mean different 
things to different people.

From: Pettit, Ghery [mailto:ghery.pet...@intel.com]
Sent: 28 October 2014 17:00
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] CE-magazine

I suspect he is looking for Compliance Engineering magazine.  :)

Ghery S. Pettit

From: Richard Nute [mailto:ri...@ieee.org]
Sent: Tuesday, October 28, 2014 9:56 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] CE-magazine


Hi David:


Suggest you contact Stefan Mozar, President of the CE Society.  
s.mo...@ieee.org


Best regards,
Rich

From: Schaefer, David [mailto:dschae...@tuvam.com]
Sent: Tuesday, October 28, 2014 6:20 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] CE-magazine

Hi all,

I'm trying to track down an article from CE magazine from a few years ago. I 
had a link to it, but it seems their website is gone. Does anyone know if there 
is an archive available anywhere else online?

Thanks,

David Schaefer
EMC Chief Technical Advisor
TÜV SÜD America Inc
Office: 651 638 0251
Cell: 612 578 6038
Fax: 651 638 0285


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Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

[Pawson, James]

But John, HDMI uses a differential signalling interface which is known to 
provide low emissions!  8-)

-Original Message-
From: John Woodgate [mailto:j...@jmwa.demon.co.uk] 
Sent: 04 September 2014 19:44
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables - a conundrum

In message
<63e38a5b081437478c77651f3d56c64f580a3...@orsmsx102.amr.corp.intel.com>,
dated Thu, 4 Sep 2014, "Pettit, Ghery"  writes:

>The problem with HDMI cables is that the HDMI standards for the cables 
>do not specify that the shields be terminated.

Is anyone complaining to HDMI about that? It seems incredible, considering the 
status of the consortium companies that developed the interface, that the EMC 
issue was not treated in depth. Even if shielding was deemed optional (why?), 
at least the termination of shielding could have been specified.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Quid 
faciamus nisi sit?
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

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Re: [PSES] FCC EMI Test and Ferrites on Cables

[Pawson, James]

I'm with Ghery on this one.

All HDMI cables are not created equal.
Screening of the backshell and connection of the cable shield is critical.

James

-Original Message-
From: Pettit, Ghery [mailto:ghery.pet...@intel.com] 
Sent: 04 September 2014 08:46
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] FCC EMI Test and Ferrites on Cables

You are highly unlikely to find the ferrite prayer beads at Best Buy.  If you 
don't specify which ones to get you have no idea what the result will be.  I 
think you are correct, the beads must be shipped with the product.  The right 
ones, to boot.

Now, how does the designer know that he needs ferrite beads?  My experience has 
been that many (most?) HDMI cables do not have their shields terminated 
properly, if at all.  Once the shields are terminated correctly problems go 
away.  Could this be a better solution?

Ghery S. Pettit

-Original Message-
From: Scott Douglas [mailto:sdouglas...@gmail.com]
Sent: Wednesday, September 03, 2014 11:31 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] FCC EMI Test and Ferrites on Cables

Fellow List persons...

Please help refresh a tired brain. A designer of a product tells us that he 
passes FCC emissions testing if he puts ferrite sleeves (beads?) on the four 
HDMI cables connected at the rear panel of the product.

He tells us that all he needs to do is add a statement in the user manual to 
the effect that the HDMI output cables must have ferrite sleeves (beads?) on 
them.

He says he does not need to specify manufacturer name and part number of the 
ferrites.

He says he does not need to provide the ferrites with the product.

He also does not plan to include the HDMI output cables with the product 
because every installation will have different length HDMI cables needed.

Now, my old brain thinks the above is not acceptable and that the FCC says that 
anything special needed to pass FCC testing must be provided with the product. 
And I am thinking that ferrites are special as you can't get them at Walmart or 
Radio Shack or Ace Hardware. And not all ferrites are the same.

Can anyone confirm my memory and maybe give a pointer to the part of the FCC 
Rules that clarify this? Or have the rules changed over the years and I just 
missed that part?

Thank you in advance for any and all comments, on list or off.

Best regards,
Scott

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[PSES] EMI Receiver Calibration

[Pawson, James]

Hi all,

Our two R+S EMI receivers (ESHS & ESVS) are due for calibration and I've got a 
spread of quotes from various labs. It seems like each lab has a different set 
of tests that they apply.

Questions:

1)  Does anyone know if there is a standard calibration routine for EMI 
receivers or, even better, these specific R+S receivers? I have an inquiry in 
with our local R+S office on the last point also.
2)  What would you consider to be a standard calibration for an EMI 
receiver?

Many thanks,

James Pawson
Leading EMC Engineer
Echostar Europe




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Re: [PSES] quiet HDMI source

[Pawson, James]

Hi Brent,
Even HDMI test sources like Quantum Data or Agilent machines are noisy and/or 
have average signal quality.
Your cables will be a significant factor, expensive =/= well shielded. But it 
sounds like you know this already.
Shopping around and doing lots of testing would probably be your best bet. 
Physically small HDMI sources will be more cost effective to totally screen.
Best of luck. In my experience you will need some.
James


-Original Message-
From: Brent G DeWitt [mailto:bdew...@ix.netcom.com] 
Sent: 11 May 2014 00:39
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] quiet HDMI source

Does anyone have a recommendation for a quiet 1080p HDMI source for radiated 
emissions testing?  The blu-ray players and simulators we are currently using 
are a mess, along with a bunch of less than well constructed HDMI cable.

Positive experiences appreciated!

Brent DeWitt
Milford, MA

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Re: [PSES] CISPR 32, colour bar with moving element

[Pawson, James]

Hello Tom,

Very helpful (and clever), I shall gladly put these to use!

Many thanks!

James Pawson
EchoStar Europe



-Original Message-
From: T.Sato [mailto:vef00...@nifty.ne.jp] 
Sent: 05 April 2014 08:51
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] CISPR 32, colour bar with moving element

Hello,

We used to use scrolling-Hs test pattern for CISPR 22 and ANSI C63.4, but CISPR 
32 requires ITU-R BT.1729 colour bar with small moving element for computer 
displays and similar devices.

Now, I made web pages which will display the test pattern on web browsers.

If you are interested, please try it, at:

http://homepage3.nifty.com/tsato/scrolling-h/colorbar.html

Regards,
Tom

--
Tomonori Sato  
URL: http://homepage3.nifty.com/tsato/

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Re: [PSES] Higher EMI from ASIC built with new process

[Pawson, James]

Hello Ravinder,

I wasn't going to answer this as you were asking the experts ;)

Flip chips couple very well into their heatsinks compared to older wirebond 
packages as the silicon is much closer to the top surface. Perhaps try 
grounding/decoupling the heatsink or changing to a ceramic material for 
diagnosis of the problem?

Also, the package bond inductance will probably have reduced. You could look at 
increasing the decoupling, especially on any digital core and driver pins.

Has the manufacturer provided updated reference schematics for the new chip?

Rgds
James Pawson
EchoStar Europe

From: ravinder.ajm...@hgst.com [mailto:ravinder.ajm...@hgst.com]
Sent: 23 March 2014 01:39
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Higher EMI from ASIC built with new process


Hi Experts,

I am comparing EMI from two ASICs.  Both have identical rise/fall times and 
signal amplitude.  Yet the ASIC built with the later technology not only has 
significantly higher radiated emissions, but also shows much broader noise 
spectrum.  PCB stackup and layout is identical.  Please help me understand what 
other factors can be responsible for this anomaly.

The older ASIC uses a wirebond package, whereas the new ASIC has flip chip 
package.

Regards
Ravinder Ajmani
HGST, a Western Digital company
5601 Great Oaks Pkwy
San Jose, CA 95119-1003
ravinder.ajm...@hgst.com
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Re: [PSES] Ethernet Loading

[Pawson, James]

Hi Julian,

EN55032 notes in table B.3 that the 10% utilisation is specifically for 
10Base-T Ethernet traffic which is electrically mostly inactive when not 
transmitting data.

100Base-T and 1000Base-T both use scrambled_idle packets to maintain a 0V DC 
bias of the AC coupled Ethernet bus meaning they are constantly active. This is 
good enough for testing the emissions caused by the PHY/connector/cable part of 
a design but probably not the MAC and upstream (i.e. the bit that generates and 
handles the data).

So perhaps this only need be a concern if you are testing 10Base-T specifically.

Anyway that wasn't what you asked. If using Linux you could investigate using 
iperf to generate traffic and tc to throttle the traffic to a manageable level. 
Being Linux commands they are free and generally well documented.

Also, if anyone has a copy of the report referenced in 55022 / 55032 for this 
clause I'd be interested in having a look.
"[7] Haas, Lee & Christensen, Ken, LAN Traffic Conditions for EMI Compliance 
Testing, IBM Corporation, Research Triangle Park, NC."

Hope this helps

James Pawson
EchoStar Europe



From: Julian Jones [mailto:ju...@hursley-emc.co.uk]
Sent: 11 March 2014 11:34
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Ethernet Loading

We have a rather convoluted way to load the ethernet lines to meet EN55022.  
Sec 9.6.3.

I've looked on Google and found a few ping and data copy programmes, but I 
can't find a single program to do it all.

I am hoping someone has found a simple program to make loading the port easy 
and getting the 10% traffic.

Thanks in advance for any pointers.


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, Chandlers Ford
EASTLEIGH, Hampshire, SO53 4BW
Company Registration 3301279

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Re: [PSES] EMC Puzzle update

[Pawson, James]

Hi Derek,

I'm glad you managed to find out what had been causing that problem. Why did 
you elect to have a separate "chassis plane" in the first place that 
(presumably) wasn't tied into the PCB ground planes? My (limited) understanding 
is that it is better to have all ground planes connected together to provide a 
good quality RF return path and minimise the chance of traces crossing plane 
splits.

Many thanks
James

From: Derek Walton [mailto:lfresea...@aol.com]
Sent: 19 December 2013 16:24
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] EMC Puzzle update

First off, many thanks to all who replied on and off list.

Most of the replies we had already addressed, but here is an update.

To re-cap, we had a sealed metal box with just a power cord, and that power 
cord had feed through type caps. In theory this should not radiate.

To save the agony that we went through what was finally identified was on a 6 
layer board, 6 traces left the sanctuary of a ground or power plane and were 
routed directly over a thin chassis plane that was incorporated to increase the 
number of chassis connections that we really needed on this board. Even though 
internal, we were able to break that connection and emissions reduced close to 
30 dB. A board re-layout is needed to really fix this issue.

As part of the debugging process, we also found that since the board chassis 
layer was "backfeeding" the Ethernet connector housing metal and the "grounding 
tabs" were just not adequate for bonding. The result was current on the outside 
of the case that cause the enclosure to radiate pretty much equally in all 
directions... Can I patent this? :-)

The lesson here is that if you do bring chassis onto your PWB, and we do as a 
means to divert ESD and some RF current, that you keep it well away from 
internal high speed or sensitive traces and ideally confined to the region 
around where it's used.

After our mods, we now have dropped from 20 dB over class A to about 13 dB 
under Class B.

A big thank you once more to everyone that replied!!! Seasons Greatings to all.

Sincerely,

Derek.
L F Research
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Re: [PSES] Job titles

[Pawson, James]

When explaining to my (non-technical) friends what I do (EMC Engineer), I 
usually say something along the lines of:

"You know when you put your mobile next to your speakers and it goes 
da-da-da-da-daaa-da-da? My job is to stop that happening to the things we 
make. We can't interfere with mobile phones and they can't interfere with our 
stuff." Simples.

(Nearly) everyone has a mobile these days so bringing the effect of what you do 
into a frame of reference that they understand is the first step. Ed's plane 
analogy is good - you are the person that stops them plummeting out of the sky 
and dying! You are a HERO!

Best of luck with the job hunting
James

From: Ed Price [mailto:edpr...@cox.net]
Sent: 01 October 2013 03:34
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Job titles

Doug:

You can be modest for all eternity, but if you want to be effective in 
marketing yourself, you have to grab their attention and reach their mind in 
just a few seconds; you have to put on a show. Obviously, this speech would be 
tailored to suite your audience, but you could start with a smile, calmly but 
confidently saying that:

I'm an engineer who, while understanding the technical aspects of your product, 
can also smooth your way into new markets, minimize your development costs, 
protect you and your company from legal attack and give your customers a reason 
for them to buy your next product.

And then, as they recover from the shock of meeting either a blowhard or the 
guy they should really hire, you move in just a bit, smile and shrug a tiny 
bit, and ask which of those areas he finds interesting and would like to talk 
about in some detail. You put the lead in his hands, and let him tell you what 
to say next.

I think that's a great approach. BTW, did I mention that I'm not employed now? 
Seriously, engineers usually are not adept salesmen, so whenever you get a 
chance, watch how good salesmen make a pitch and close a deal. Volunteer to do 
a field trip with your company's best salesman and observe how he does things; 
ask him about strategy and tactics. You might not think you are a salesman, but 
you are always selling yourself, always.

When I would be asked what I did, I would generally say that I was an EMC 
engineer, and I worked to make sure that electronic gadgets worked happily with 
other electronic gadgets. I would go on to say that, for instance, as a pilot 
gets ready to take off, he might dial in 15 degrees of wing flaps, and little 
electric motors in the airplane would move the wing flaps. And I was the one 
who made sure those motors didn't confuse the other circuits in the plane and 
accidently erase the navigation computer or command the wheels to fold up.

That was about the limit of average citizen's attention span, so you need to 
learn when to stop and change the subject, like asking them how they polish 
bowling balls or something.

Ed Price
WB6WSN
Chula Vista, CA USA

From: Doug Powell [mailto:doug...@gmail.com]
Sent: Monday, September 30, 2013 6:18 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Job titles

All,

Of all the people on this forum I'm certain we all share to some extent the 
same quandary.

I am currently searching for work either as full time or as contract. Part of 
the coaching I received is to develop a 30 second elevator speech to describe 
myself to almost anyone. One of the difficulties I face is confusion about the 
general term Compliance Engineer.

Often I see people confuse this with a compliance officer in banking or a 
medical professional of some kind. A third possibility is some sort of a field 
auditor.

My question is, how do any of you express what you do to the uninitiated, 
whether in a job title or even to family and friends?

Thanks, - doug

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

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Re: [PSES] OATS vs FAR Radiated Emissions Limits

[Pawson, James]

Thanks for all the feedback, I shall follow up on the information kindly 
provided.
I particulary enjoyed some of the stories.

Regards,
James


From: Pawson, James
Sent: 16 October 2012 15:27
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] OATS vs FAR Radiated Emissions Limits


We've just received EN 61000-6-3:2007 + A1:2011 which has added the ability to 
test radiated emissions in either an OATS, Fully Anechoic Room (FAR) or TEM 
waveguide.

What puzzled me is the limits for the FAR @ 3m:

30MHz ~ 230MHz: 42 to 35dBuV decreasing linearly with the log of the 
frequency
230MHz ~ 1GHz: 42dBuV

Checking a draft version of CISPR 32 also shows these same limits for an FAR.

These limits are lower than those for an OATS at 3m. Does anyone know why the 
limits are lower and of a different characteristic? I'm guessing something to 
do with the lack of reflective ground plane in the FAR.

Does anyone have any further information?

Many thanks
James

~
James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe


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All emc-pstc postings are archived and searchable on the web at:
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[PSES] OATS vs FAR Radiated Emissions Limits

[Pawson, James]

We've just received EN 61000-6-3:2007 + A1:2011 which has added the ability to 
test radiated emissions in either an OATS, Fully Anechoic Room (FAR) or TEM 
waveguide.

What puzzled me is the limits for the FAR @ 3m:

30MHz ~ 230MHz: 42 to 35dBuV decreasing linearly with the log of the 
frequency
230MHz ~ 1GHz: 42dBuV

Checking a draft version of CISPR 32 also shows these same limits for an FAR.

These limits are lower than those for an OATS at 3m. Does anyone know why the 
limits are lower and of a different characteristic? I'm guessing something to 
do with the lack of reflective ground plane in the FAR.

Does anyone have any further information?

Many thanks
James

~
James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe



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Re: [PSES] DVI-D drivers and displays

[Pawson, James]

Based on my experiences with HDMI I've found the high speed TMDS interface used 
on DVI (and HDMI) can be very difficult to control indeed.

Cable backshell shielding is critical to low radiated emissions. 360º 
continuous shielding between cable shield and connector shell is required. 
Finding a good cable is often a case of trial and error - once yo do it is 
worth buying several as they can wear out and change characteristics with heavy 
use.

Sometimes common mode noise on the differential TMDS pairs will cause problems 
that even a good cable won't fix. High speed common mode chokes on the diff 
pairs are required here.

Happy hunting
James


James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe


From: McInturff, Gary [mailto:gary.mcintu...@esterline.com]
Sent: 19 September 2012 20:59
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] DVI-D drivers and displays

Does anyone else have as much trouble with these monitors as I seem to have. 
One could almost cook popcorn on top of some of the monitors we have for the 
lab - makes trying to measure the stuff we are generating difficult and annoys 
all to heck.
Using a computer with an expansion bus card driving the monitor. They are both 
brand name pieces of equipment, but I get 40 MHz multiples that can be above 
class A all over the place. I've had to run this type of video in a couple of 
different applications, with different monitors and get pretty much the same 
response, the cable itself is hotter than heck, but again not something I can 
control - well I probably could but then I end up with a "lab queen" support 
computer.
Grr - anybody else having similar problems




Gary McInturff
Reliability/Compliance Engineer








Esterline Interface Technologies

Featuring
ADVANCED INPUT, MEMTRON, and LRE MEDICAL products



600 W. Wilbur Avenue
Coeur d'Alene, ID  83815-9496
Office:208-635-8306
Cell:  509 868 2279
Toll Free: 800-444-5923 X 1238
gary.mcintu...@esterline.com


www.esterline.com/interfacetechnologies

Technology, Innovation, Performance...



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Re: [PSES] 61000-4-3: Rate of application of field

[Pawson, James]

Hi and thanks for all the insightful emails. The way we perform the test 
in-house is...
unmodulated > frequency set > level set from cal (instant application, no ramp) 
> apply modulation > dwell time > unmodulated > next freq
I think we are all agreed that different test methods can result in different 
EUT behaviour. It would also appear that there is no consensus for an agreed 
method of testing.

My main line of enquiry was to clarify the test procedure. I have seen cases 
where applying the field suddenly results in a momentary disturbance to the EUT 
that disappears resulting in a stable operating EUT during the dwell time. A 
slow increase in the field does not result in this momentary disturbance.

Lack of a directional coupler means that measuring the RF field in realtime is 
difficult in our case to see what is happening at the moment of applying the 
modulation and changing the level.

I guess the dwell time starts as soon as a stable RF field has been established.

I'm also going to investigate leaving the RF modulation on and redoing our test 
procedure to level set with the modulation on constantly to see what difference 
that makes.

Many thanks
James


________
From: Pawson, James
Sent: 20 August 2012 10:54
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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[PSES] 61000-4-3: Rate of application of field

[Pawson, James]

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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[PSES] Raspberry Pi Shipping Delayed Due To CE Testing

[Pawson, James]

Hopefully their compliance guy is having a straightforward time of things!

http://www.reghardware.com/2012/03/29/raspberry_pi_supplier_apologises_for_ship_date_delay_glitch/

http://www.raspberrypi.org/archives/852

Worth reading the last link for some of the commentards :P


James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe



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Re: [PSES] Antenna Pattern for 2.4 GHz and 5GHz

[Pawson, James]

Hi Ed,

I've been making antenna pattern measurements recently in our chamber and I too 
see a variation as you described. One theory I'm working on is that our 
turntable might not be as accurate in it's 5º increments as it could be. If the 
set point has a tolerance of 1-2º and that lies on the relatively "steep" side 
of a lobe then you might expect a large variation for a relatively small 
positional change.

With regards,
James



James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe


From: Ed Price [mailto:edpr...@cox.net]
Sent: 25 February 2012 09:26
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Antenna Pattern for 2.4 GHz and 5GHz

If you took a reference level at the start of a 180-degree rotation, after 
stepping 180 degrees CW, then 360 degrees CCW and then 180 degrees CW, 
sometimes you could go back to the original point and get a new level that was 
less than 0.5 dB different. And sometimes the level had changed 2 dB, so you 
got to repeat the test.


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Re: [PSES] British plug gets a makeover

[Pawson, James]

Currently only available as a USB adaptor for charging phones/MP3 players/etc 
with

http://themu.co.uk/


From: Pettit, Ghery [mailto:ghery.pet...@intel.com]
Sent: 21 February 2012 16:03
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] British plug gets a makeover

Wonderful, if you don't mind dropping 25 pounds on a plug that's only good for 
non-grounded applications.  Interesting design, however.

Ghery S. Pettit

From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Ken Wyatt
Sent: Tuesday, February 21, 2012 7:25 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: British plug gets a makeover

I thought this was interesting...

British plug gets a makeover
http://www.coolest-gadgets.com/20120220/british-plug-makeover/

---
Sent from Zite personalized magazine iPhone app.
Available for free in the App 
Store.
___
Kenneth Wyatt
Wyatt Technical Services LLC
Woodland Park, CO
Email Me! | Web Site 
| Blog
Subscribe to Newsletter
Connect with me on LinkedIn

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Re: [PSES] FCC - Intentional Radiators, Restricted Bands and 960 MHz

[Pawson, James]

Hi Bob,

This is a Wi-Fi product which I believe is DSSS and not frequency hopping. I 
will review the document anyway but will it be relevant do you think?

Many thanks
James


From: rehel...@mmm.com [mailto:rehel...@mmm.com]
Sent: 15 February 2012 13:44
To: Pawson, James
Cc: emc-p...@ieee.org
Subject: RE: FCC - Intentional Radiators, Restricted Bands and 960 MHz

Are you measuring according to DA 00-705? That should help.

Bob Heller
3M EMC Laboratory, 76-1-01
St. Paul, MN 55107-1208
Tel: 651-778-6336
Fax: 651-778-6252
=




From:"Pawson, James" 
To:"'Grace Lin'" 
Cc:"EMC-PSTC@LISTSERV.IEEE.ORG" 
Date:02/15/2012 07:03 AM
Subject:RE: FCC - Intentional Radiators, Restricted Bands and 960 MHz
Sent by:emc-p...@ieee.org




Hi Grace,

That's a very useful document for measuring the RF path, thanks for the info. 
The issue we have is that the RF path is not the only path for the emissions at 
960MHz from the equipment under test so measuring just the conducted output 
into the antenna would not give the whole picture.

Thanks
James


From: Grace Lin [mailto:graceli...@gmail.com]
Sent: 15 February 2012 12:42
To: Pawson, James
Cc: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: FCC - Intentional Radiators, Restricted Bands and 960 MHz

James,

FCC published a new DTS procedure, FCC KDB 558074 D01 DTS Meas Guidance v01 
<https://apps.fcc.gov/kdb/GetAttachment.html?id=39668> , on January 18, 2012.  
If you are able to connect the antenna port of the device under test to the 
instrument (spectrum analyzer, through attenuators if needed), you may wish to 
use this procedure.  FCC has done a great job on this procedure (save 
engineers' time and have better repeatability).

If you need a sample test report using the FCC DTS procedure, DTS Measurement 
<https://apps.fcc.gov/kdb/GetAttachment.html?id=20422> , published March 23, 
2005, you may wish to look the report under FCC ID: EROCWD6660 or FCC ID: 
EROCWD6782.  These two applications were granted by the FCC.  Conducted 
measurement was used to take -20dBc data (screen captures).

With regards,
Grace Lin
On Wed, Feb 15, 2012 at 5:46 AM, Pawson, James 
mailto:james.paw...@echostar.com>> wrote:

Bit of a regulatory puzzler here, please bear with me.

Testing an intentional radiator to FCC 15.247. Spurious emissions allowed to be 
-20 dBc except in the 15.205 restricted bands where the general radiated 
emissions limits in 15.209.

Radiated emissions limits: 216 ~ 960 MHz = 200 uV/m, 960 MHz upwards = 500 uV/m
The tighter (lower) limit applies at the band edges so at 960 MHz the limit is 
200 uV/m

Restricted Bands includes 960 MHz to 1240 MHz

I've drawn a picture to help explain -- 
http://thedatastream.4hv.org/data/fcc_15-247_960mhz_limit_line_question.gif


My question is - what is the limit at 960 MHz for spurious emissions from an 
intentional radiator?


My interpretation (to the letter of part 15) is that for 960 MHz only, the 
limit is 200 uV/m. However this doesn't follow a common sense approach to the 
limits and restricted bands (the green limit line on the picture).

We currently have an issue with a product with emissions around 960 MHz that 
would cause it to fail the strict interpretation of the standard but pass the 
"common sense approach" interpretation. So any assistance is greatly 
appreciated :)

Thanks in advance
James


James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe





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Re: [PSES] FCC - Intentional Radiators, Restricted Bands and 960 MHz

[Pawson, James]

Hi Grace,

That's a very useful document for measuring the RF path, thanks for the info. 
The issue we have is that the RF path is not the only path for the emissions at 
960MHz from the equipment under test so measuring just the conducted output 
into the antenna would not give the whole picture.

Thanks
James


From: Grace Lin [mailto:graceli...@gmail.com]
Sent: 15 February 2012 12:42
To: Pawson, James
Cc: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: FCC - Intentional Radiators, Restricted Bands and 960 MHz

James,

FCC published a new DTS procedure, FCC KDB 558074 D01 DTS Meas Guidance v01 
<https://apps.fcc.gov/kdb/GetAttachment.html?id=39668> , on January 18, 2012.  
If you are able to connect the antenna port of the device under test to the 
instrument (spectrum analyzer, through attenuators if needed), you may wish to 
use this procedure.  FCC has done a great job on this procedure (save 
engineers' time and have better repeatability).

If you need a sample test report using the FCC DTS procedure, DTS Measurement 
<https://apps.fcc.gov/kdb/GetAttachment.html?id=20422> , published March 23, 
2005, you may wish to look the report under FCC ID: EROCWD6660 or FCC ID: 
EROCWD6782.  These two applications were granted by the FCC.  Conducted 
measurement was used to take -20dBc data (screen captures).

With regards,
Grace Lin
On Wed, Feb 15, 2012 at 5:46 AM, Pawson, James 
mailto:james.paw...@echostar.com>> wrote:

Bit of a regulatory puzzler here, please bear with me.

Testing an intentional radiator to FCC 15.247. Spurious emissions allowed to be 
-20 dBc except in the 15.205 restricted bands where the general radiated 
emissions limits in 15.209.

Radiated emissions limits: 216 ~ 960 MHz = 200 uV/m, 960 MHz upwards = 500 uV/m
The tighter (lower) limit applies at the band edges so at 960 MHz the limit is 
200 uV/m

Restricted Bands includes 960 MHz to 1240 MHz

I've drawn a picture to help explain -- 
http://thedatastream.4hv.org/data/fcc_15-247_960mhz_limit_line_question.gif


My question is - what is the limit at 960 MHz for spurious emissions from an 
intentional radiator?


My interpretation (to the letter of part 15) is that for 960 MHz only, the 
limit is 200 uV/m. However this doesn't follow a common sense approach to the 
limits and restricted bands (the green limit line on the picture).

We currently have an issue with a product with emissions around 960 MHz that 
would cause it to fail the strict interpretation of the standard but pass the 
"common sense approach" interpretation. So any assistance is greatly 
appreciated :)

Thanks in advance
James


James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe





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[PSES] FCC - Intentional Radiators, Restricted Bands and 960 MHz

[Pawson, James]

Bit of a regulatory puzzler here, please bear with me.

Testing an intentional radiator to FCC 15.247. Spurious emissions allowed to be 
-20 dBc except in the 15.205 restricted bands where the general radiated 
emissions limits in 15.209.

Radiated emissions limits: 216 ~ 960 MHz = 200 uV/m, 960 MHz upwards = 500 uV/m
The tighter (lower) limit applies at the band edges so at 960 MHz the limit is 
200 uV/m

Restricted Bands includes 960 MHz to 1240 MHz

I've drawn a picture to help explain -- 
http://thedatastream.4hv.org/data/fcc_15-247_960mhz_limit_line_question.gif


My question is - what is the limit at 960 MHz for spurious emissions from an 
intentional radiator?


My interpretation (to the letter of part 15) is that for 960 MHz only, the 
limit is 200 uV/m. However this doesn't follow a common sense approach to the 
limits and restricted bands (the green limit line on the picture).

We currently have an issue with a product with emissions around 960 MHz that 
would cause it to fail the strict interpretation of the standard but pass the 
"common sense approach" interpretation. So any assistance is greatly 
appreciated :)

Thanks in advance
James


James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe






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[PSES] Wanted: Screened Room

[Pawson, James]

Hi folks,

We are looking at the possibility of expanding our test facilities with a 
screened room. This would be

Does anyone know of any surplus screened rooms for sale in the United Kingdom / 
Western Europe area?

Alternately, does anyone have any tips for building one? Obvious problem is 
construction of the door but other comments appreciated.

Lastly, are there any companies people could recommend for the supply / 
installation of such a room?

Probably looking at something about the 8 foot (2.4m) cubed sort of volume

I'm also Googling in parallel before Brian says anything ;)

Many thanks
James


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Re: [PSES] Radiated Emissions Testing of Intentional Radiators - Practicalities?

[Pawson, James]

Thank you to all who responded with some very practical hints and tips. As 
recommended by several people I'm keeping the AP outside of the chamber and 
putting some SMA connectors through the bulkhead to attach the antennas.

Many thanks
James



From: Pawson, James [mailto:james.paw...@echostar.com]
Sent: 10 January 2012 16:13
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] Radiated Emissions Testing of Intentional Radiators - 
Practicalities?


Hello list members,

We are wanting to test one of our products, which contains a WiFi interface, in 
our anechoic chamber. To ensure the WiFi is active we would need to set up 
antennae in the anechoic chamber itself - the irony of introducing radio into a 
radio-quiet environment is not lost on me.

I'm concerned about separating out the emissions from the WiFi access point and 
the emissions of the equipment under test. Does anyone have any practical 
pointers / hints / tips / experience / pitfalls of doing this?

Thanks in advance
James

James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe


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[PSES] Radiated Emissions Testing of Intentional Radiators - Practicalities?

[Pawson, James]

Hello list members,

We are wanting to test one of our products, which contains a WiFi interface, in 
our anechoic chamber. To ensure the WiFi is active we would need to set up 
antennae in the anechoic chamber itself - the irony of introducing radio into a 
radio-quiet environment is not lost on me.

I'm concerned about separating out the emissions from the WiFi access point and 
the emissions of the equipment under test. Does anyone have any practical 
pointers / hints / tips / experience / pitfalls of doing this?

Thanks in advance
James

James Pawson
Leading Hardware Engineer - EMC
EchoStar Europe



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Re: [PSES] What means do you use to exercise Ethernet telecom ports?

[Pawson, James]

Hi Charles,

To clarify my comment (which in retrospect is not at all clear!) - what I meant 
was you can't simply monitor "link up status" and extrapolate performance of 
the interface based just on this. Software response time and the criteria by 
which link up is decided are too variable in my opinion.

Monitoring the quality of the link by streaming video should be more than 
adequate to judge compliance with the criteria that Mr Carpentier higlighted 
provided the bitrate of the stream and number of permissible errors 
(visual/measured) is defined by the manufacturer in the EMC assesment as Mr 
Woodgate points out.

Also, testing streaming video tests pretty much the entire signal chain for a 
set top box so this is as valid a test as you can get :)

Happy new year and all that
James



From: Grasso, Charles
Sent: 30 December 2011 18:01
To: Pawson, James; 'Chris Wells'; 'Knighten, Jim L'; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: What means do you use to exercise Ethernet telecom ports?

Hello James,

In your response you said: "it is not easy to monitor the quality of the link 
for judging performance against immunity criteria A/B/C"
as a downside to the loopback method.  I have also had other responses that 
detailed the requirements from CISR24 as to the monitoring of
transmission performance during an immunity test. While I can see that might be 
an issue for server farms and the like - but for
AV equipment surely not!

My question (for the group) is : Why (for streaming video) is it necessary to 
monitor the link minutia?  Surely the test requirement is that the video will 
continue undisturbed under excitation from external fields. As long as my 
viewing experience is uninterrupted - then that's a PASS.

(I can see how monitoring the stream might be beneficial for diagnosing 
immunity issues).

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: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Pawson, James
Sent: Thursday, December 29, 2011 2:55 AM
To: 'Chris Wells'; 'Knighten, Jim L'; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: What means do you use to exercise Ethernet telecom ports?

Hi Chris,

As for the CISPR 22 conducted emissions test that Jim mentioned in his orginal 
message the measurement is made using an ISN which defines the CM impedance of 
the AE so no issues there. You would also have to make sure that the cable 
lengths / distances to the walls of the test chamber were as per the standard 
and that would be your CM impedance defined.

For CISPR 24 conducted immunity testing (using 61000-4-6) the noise is injected 
using a CDN (very similar to an ISN) which again provides a defined CM 
impedance.

I guess also the CM impedance for a radiated emissions test would also be OK as 
the dimensions / orientation of the cable bundle is defined.

Another disadvantage to the simple loopback method that I just thought about is 
that it is not easy to monitor the quality of the link for judging performance 
against immunity criteria A/B/C. You can monitor the Link Up status in the 
software to a first approximation but data transfer / ping is more suitable in 
this case.

As for your "emissions quiet" transciever it is possible to execute a cheap but 
effective Cat-5 chamber entry/exit filter that effectivley removes any CM 
emissions from the incoming lead. Not quite what you were asking for though :(

Regards,
James

____
From: Chris Wells [mailto:radioactive55...@comcast.net]
Sent: 28 December 2011 17:03
To: Pawson, James; 'Knighten, Jim L'; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: What means do you use to exercise Ethernet telecom ports?
James/Jim
I like the loop back test idea for preliminary EMI testing due to the 
simplicity.
However another issue is that it lacks the common mode impedance relationship 
at the AE end.
I suppose one could use a long enough cable to create some capacitive 
relationship to the ground plane but the pulse transformer at the far end would 
not be there.

Back to the AE side of this discussion:
I am having similar issues in doing some preliminary emission testing where I 
was using a Cat5 to fiber optic transceiver as the AE end (another FO/Cat5 
outside the chamber to my notebook).
This approach worked well for EMI testing since the transceiver was robust 
enough but I found that my transceiver was a major source of emissions during 
my emission testing.
Can anyone suggest an "emission quite" FO/Cat5 transceiver that would behave 
for my testing?

Thanks

Chris Wells
Eaton Corp.

Subject: RE: What means do you use to exercise Ethernet teleco

Re: [PSES] What means do you use to exercise Ethernet telecom ports?

[Pawson, James]

Hi Chris,

As for the CISPR 22 conducted emissions test that Jim mentioned in his orginal 
message the measurement is made using an ISN which defines the CM impedance of 
the AE so no issues there. You would also have to make sure that the cable 
lengths / distances to the walls of the test chamber were as per the standard 
and that would be your CM impedance defined.

For CISPR 24 conducted immunity testing (using 61000-4-6) the noise is injected 
using a CDN (very similar to an ISN) which again provides a defined CM 
impedance.

I guess also the CM impedance for a radiated emissions test would also be OK as 
the dimensions / orientation of the cable bundle is defined.

Another disadvantage to the simple loopback method that I just thought about is 
that it is not easy to monitor the quality of the link for judging performance 
against immunity criteria A/B/C. You can monitor the Link Up status in the 
software to a first approximation but data transfer / ping is more suitable in 
this case.

As for your "emissions quiet" transciever it is possible to execute a cheap but 
effective Cat-5 chamber entry/exit filter that effectivley removes any CM 
emissions from the incoming lead. Not quite what you were asking for though :(

Regards,
James


From: Chris Wells [mailto:radioactive55...@comcast.net]
Sent: 28 December 2011 17:03
To: Pawson, James; 'Knighten, Jim L'; EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: What means do you use to exercise Ethernet telecom ports?

James/Jim
I like the loop back test idea for preliminary EMI testing due to the 
simplicity.
However another issue is that it lacks the common mode impedance relationship 
at the AE end.
I suppose one could use a long enough cable to create some capacitive 
relationship to the ground plane but the pulse transformer at the far end would 
not be there.

Back to the AE side of this discussion:
I am having similar issues in doing some preliminary emission testing where I 
was using a Cat5 to fiber optic transceiver as the AE end (another FO/Cat5 
outside the chamber to my notebook).
This approach worked well for EMI testing since the transceiver was robust 
enough but I found that my transceiver was a major source of emissions during 
my emission testing.
Can anyone suggest an "emission quite" FO/Cat5 transceiver that would behave 
for my testing?

Thanks

Chris Wells
Eaton Corp.

Subject: RE: What means do you use to exercise Ethernet telecom ports?

Hi Jim,

As a basic test you can make an RJ45 connector that connects the EUT TX lines 
to the RX lines thus looping back the Ethernet interface onto itself. This 
certainly works for 100BaseTX because the EUT sees it's own Link Test Pulse, 
assumes it is connected to another Ethernet interface and then activates it's 
scrambled_idle packet mode. This is a 100BaseTX PRBS sequence that maintains a 
net 0Vdc bias on the lines which is used to get round the issues with first 
pulse as seen on 10Base-T

Advatanges of this method
- it doesn't require other equipment in the chamber / test area
- very cheap to make
- no software support required so useful for a at the start of EUT validation 
testing

Disadvantages
- the EUTs PHY (and maybe a bit of the MAC) is the only part of the EUT 
Ethernet interface that is activated. As other posters have pointed out, 
pinging, file transfer will generate electrical activity futher up the 7-layer 
OSI model
- you might not be able to ping or generate traffic at all as the EUT might 
figure out it is connected to itself and redirect traffic internally (this 
statement is a guess)

I would imagine that it would work with Gigabit as this should use 
scrambled_idle packets as well.

If you want to use an application to get data moving over a network connection 
I would highly recommend using iperf (http://sourceforge.net/projects/iperf/) 
which is primarily a network testing tool. It transfers far more data than 
ping, can do bidirectional data transfer and if highly configurable. The 
command line interface is easy to use, can't comment on the jperf GUI. 
Disadvantage against ping is that it requires iperf to be running on both ends 
of the link whereas ping doesn't

Hope this helps
James

 Subject: [PSES] What means do you use to exercise Ethernet telecom ports?
I am curious what means people are using to exercise Ethernet telecom ports 
when testing for conducted emissions according to CISPR 22 and conducted 
immunity according to CISPR 24?

Do you use an external piece of equipment (AE) to send Ethernet traffic?  If 
so, what do you use and do you like it?

My particular interest is 1000BaseT (gigabit Ethernet), but the question is 
more general.

Thanks in advance,

Jim

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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 
mailto:

Re: [PSES] What means do you use to exercise Ethernet telecom ports?

[Pawson, James]

Hi Jim,

As a basic test you can make an RJ45 connector that connects the EUT TX lines 
to the RX lines thus looping back the Ethernet interface onto itself. This 
certainly works for 100BaseTX because the EUT sees it's own Link Test Pulse, 
assumes it is connected to another Ethernet interface and then activates it's 
scrambled_idle packet mode. This is a 100BaseTX PRBS sequence that maintains a 
net 0Vdc bias on the lines which is used to get round the issues with first 
pulse as seen on 10Base-T

Advatanges of this method
- it doesn't require other equipment in the chamber / test area
- very cheap to make
- no software support required so useful for a at the start of EUT validation 
testing

Disadvantages
- the EUTs PHY (and maybe a bit of the MAC) is the only part of the EUT 
Ethernet interface that is activated. As other posters have pointed out, 
pinging, file transfer will generate electrical activity futher up the 7-layer 
OSI model
- you might not be able to ping or generate traffic at all as the EUT might 
figure out it is connected to itself and redirect traffic internally (this 
statement is a guess)

I would imagine that it would work with Gigabit as this should use 
scrambled_idle packets as well.

If you want to use an application to get data moving over a network connection 
I would highly recommend using iperf (http://sourceforge.net/projects/iperf/) 
which is primarily a network testing tool. It transfers far more data than 
ping, can do bidirectional data transfer and if highly configurable. The 
command line interface is easy to use, can't comment on the jperf GUI. 
Disadvantage against ping is that it requires iperf to be running on both ends 
of the link whereas ping doesn't

Hope this helps
James




From: Knighten, Jim L [mailto:jim.knigh...@teradata.com]
Sent: 28 December 2011 00:05
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] What means do you use to exercise Ethernet telecom ports?

I am curious what means people are using to exercise Ethernet telecom ports 
when testing for conducted emissions according to CISPR 22 and conducted 
immunity according to CISPR 24?

Do you use an external piece of equipment (AE) to send Ethernet traffic?  If 
so, what do you use and do you like it?

My particular interest is 1000BaseT (gigabit Ethernet), but the question is 
more general.

Thanks in advance,

Jim

__

James L. Knighten, Ph.D.
EMC Engineer
Teradata Corporation
17095 Via Del Campo
San Diego, CA 92127

858-485-2537 - phone
858-485-3788 - fax (unattended)






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http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used 
formats), large files, etc.

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