Hi Chaz,
Regarding variability between tests and test sites, you wrote:
> there is one technique (that has fallen out of favor) that can help
to ameliorate
> some of these concerns and that is cable maximization. Cable
maximization IS time
> consuming frustrating at times but it will minimize your risks at a
3rd part location.
I agree. Especially as one is designing a product, it is important to
really get to know the product's emissions performance and weaknesses by
taking some time to manipulate cables. However, this is only done as a
part of engineering experimentation. The final qualification of the
product to create a test report that can be used for agencies must be
performed according to the standards. There are so many rules about
bundling excess cable at specific heights and draping cables to specific
heights that there is very little cable manipulation that could be
possibly be done and still comply with the setup requirements, so the
standards no longer call for cable manipulation to be done. The good
news is that this speeds up the test.
CISPR32 says: "The arrangement for formal measurement shall be
representative of a typical arrangement of the EUT, local AE and
associated cabling." Both CISPR32 and ANSI C63.4 give some very
specific test configuration arrangement requirements with figures. To
setup a product correctly (especially a tabletop product) one must have
a measuring stick or measuring tape on hand.
Have fun!
Monrad
Note: /The statements and opinions expressed here are my own and do not
necessarily represent those of any company I work for/.
On 9/25/2014 9:54 AM, Grasso, Charles wrote:
Apologies for the late response on this but the concerns raised (market
surveillance, test methodologies and standards
interpretation) go right to the heart of the compliance engineering function -
and has been this way for about 30 years!
Kris - the standards piece seems to be pretty well laid out, however you asked
a key question at the end of your original
email that raised my interest!
You asked: "So to me it looks sufficient to test a typical set-up, do your best to
not make it best case and describe everything in the report" . This statement
embraces the issue of consistent and accurate emissions testing because
with that your concerns of failing due to a 3rd party test would be much
reduced.
However due to the very nature of the systems level of the test, the
variabilities between sites, measurement
uncertainty (which by itself acknowledges the variability in our test
equipment!) and manufacturing variances makes
consistent testing challenging. However there is one technique (that has
fallen out of favor) that can help
to ameliorate some of these concerns and that is cable maximization. Cable
maximization IS time consuming
frustrating at times but it will minimize your risks at a 3rd part location.
Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) [email protected]
(e) [email protected]
(e2) [email protected]
-----Original Message-----
From: Carpentier Kristiaan [mailto:[email protected]]
Sent: Friday, September 05, 2014 8:36 AM
To: [email protected]
Subject: [PSES] Failure of Radiated emission
Hi group,
A ITE product is tested to EN55022 Radiated emission with a well defined setup
(cables, traffic, etc...) trying to find the worst case emissions and it passes.
I think finding the real worst case emission for all frequencies with one and
the same set-up is in practice not possible in practice.
That same product is retested by a customer or in case of market surveillance
campaigns, then it is most likely not tested with the same set-up and results
may fail.
Would this be an issue or is it acceptable that it is retested with the same
set-up as the initial testing? I refer to CISPR22, clause 8.4 that states that
the operational conditions of the EUT shall be determined acc. to typical
use.....The operat mode and rationale shall be stated in the report.
So to me it looks sufficient to test a typical set-up, do your best to not make
it best case and describe everything in the report.
Any other thoughts?
Best regards,
Kris Carpentier
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