A well known EMC consultant in Silicon Valley who is now employed in a
well known company here presented (when he was still an independent
consultant) a very well justified case to show that the total
uncertainties for EMC test equipment, site attenuation, weather,
manufacturing tolerances, operator variances, test methodology, etc.,
were such that a minimum 6 dB margin is justified. 10 dB would be
better.
Lets hear it from all of you other consultants, since, I suspect, many
in this industry would not like to proclaim publicly just what the
situation is in our companies.
Tania Grant, Octel Communications Corporation
[email protected]
______________________________ Reply Separator _________________________________
Subject: dBmargin
Author: [email protected] at P_Internet_mail
List-Post: [email protected]
Date: 10/9/96 2:59 PM
I don't know about all of you, but I am sick of arguing with
hardware engineering managers about what constitutes
a passing EMC test and what does not.
I have seen companies impose a 6dB margin requirement,
some 5 dB, and some 3dB.
I have made the recommendation that the minimum here
should be 3dB. I thought that this was fair. Now comes
the product that has 2.8dB margin. Being a stick by the
rules type of person, I listened to the engineer explain
that it was the lousy PC his card was in not his card. So
I suggested that we prove his theory, purchase a new
machine and check the old machine versus the new
one and if there is an improvement, that I would let
the 2.8dB stand.
Of course the manager of the group tells me that as
a recommendation 3dB is good, but as a rule it
is IRRESPONSIBLE. Thus I end up with the "be
a b___ch" option of imposing the retest for the .2dB
or starting a precedence of well if .2 is okay, is .3 etc.
etc.
What I would like to do is take a pole. (must be election
year in the USA!!!!!!!!!!!) I would like all of you to respond
as to what you feel is appropriate. Then I'll run the
stats and let you what the results are. This way I can
go back to the manager with the number of certification
experts that responded and what they thought was right.
He or I will have a hard time arguing against stats.
(I am open to the possibility that I am wrong and
0 margin is acceptable).
Just reply with a number and I'll let you know what happens.
Thanks
Cynthia
[email protected]
