Well said Ralph!
On 10/7/2024 8:12 PM, Ralph McDiarmid wrote:
“I have seen differences of 9 dB on the same measurement on an EUT and
comb generator by different accredited labs! “
Doug, I recall this has been the case for decades. There are a lot of
variables to consider, and some are hard to assign a value. The
equipment has been refined somewhat over those same decades, but the
physics remains unchanged and still produce the same challenges with
measurement uncertainty.
It’s only a problem if that uncertainly creates, well… a problem.
Otherwise, EMC measurement is an approximate science, all but
impossible to model accurately, and yet universally accepted as fit
for purpose.
Ralph
*From:*doug emcesd.com <[email protected]>
*Sent:* October 7, 2024 4:08 PM
*To:* [email protected]
*Subject:* [PSES] technical musings
Hi All,
When I was a young engineer at AT&T Bell Labs, about 50 years ago, my
designs had to have an amplitude tolerance of +/- 1/10^th dB to meet
requirements (even without computer simulation). So when I came across
EMC topics later on I was initially surprised to see tolerances like
+/-2 dB or more. To me this means either the engineers do not
understand the designs, or (and I think this is the case) there are
too many uncontrolled variables to allow a narrower tolerance. I have
seen differences of 9 dB on the same measurement on an EUT and comb
generator by different accredited labs!
I personally think that Silicon Valley is the best place to do EMC
testing because there are so many labs, very close to each other,
there that they are driven to be very close to each other in
measurement results (otherwise the outliers would go out of business,
quickly). Given a choice, I would test in Silicon Valley.
On a separate topic, I am 77 years old but have the physical and
mental capabilities of a 30 year old from my 50 year experiment to
slow the aging process, which has proven to be a success for me. We
often unofficially discus this after my seminars are finished for the
day. On a recent seminar, the attendees kept me over for two hours
after the seminar, questioning me and taking notes. This is not part
of the seminar, but a significant freebie available to the attendees.
I run 3,000+ miles per year, even on 120°F days in the Southern Nevada
desert. Such heat does not even feel stressful to me! I design my own
hydration. I designed my own nutrition and supplement plans as well. I
never get sick, and am immune from sunburn from one of my supplements,
astaxanthin. This comes from applying science and engineering to my
mind and body. I have read many, many thousands of pages of medical
research in my life and make use of it!
Another topic, my classes are focused on finding hidden design flaws
in designs that can cause a manufacturing or field disaster,
especially flaws that result in a problem once in a week or month of
significant consequence that cannot be found by normal engineering
methods. Next one is in a few weeks, mid-October. Contact me if
interested.
Doug
------------------------------------------------------------------------
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 [email protected]
All emc-pstc postings are archived and searchable on the web at:
https://www.mail-archive.com/[email protected]/
<https://www.mail-archive.com/[email protected]/%20>
Website: https://ewh.ieee.org/soc/pses/
Instructions: https://ewh.ieee.org/soc/pses/list.html (including how
to unsubscribe) <https://ewh.ieee.org/soc/pses/list.html>
List rules: https://ewh.ieee.org/soc/pses/listrules.html
For help, send mail to the list administrators:
Mike Sherman at: [email protected]
Rick Linford at: [email protected]
For policy questions, send mail to:
Jim Bacher at: [email protected]
------------------------------------------------------------------------
To unsubscribe from the EMC-PSTC list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
<https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1>
------------------------------------------------------------------------
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 [email protected]
All emc-pstc postings are archived and searchable on the web at:
https://www.mail-archive.com/[email protected]/
Website: https://ewh.ieee.org/soc/pses/
Instructions: https://ewh.ieee.org/soc/pses/list.html (including how
to unsubscribe) <https://ewh.ieee.org/soc/pses/list.html>
List rules: https://ewh.ieee.org/soc/pses/listrules.html
For help, send mail to the list administrators:
Mike Sherman at: [email protected]
Rick Linford at: [email protected]
For policy questions, send mail to:
Jim Bacher at: [email protected]
------------------------------------------------------------------------
To unsubscribe from the EMC-PSTC list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
-
----------------------------------------------------------------
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
[email protected]
All emc-pstc postings are archived and searchable on the web at:
https://www.mail-archive.com/[email protected]/
Website: https://ewh.ieee.org/soc/pses/
Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to
unsubscribe)
List rules: https://ewh.ieee.org/soc/pses/listrules.html
For help, send mail to the list administrators:
Mike Sherman at: [email protected]
Rick Linford at: [email protected]
For policy questions, send mail to:
Jim Bacher: <[email protected]>
_________________________________________________
To unsubscribe from the EMC-PSTC list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
