________________________________
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Ken
Javor
Sent: Friday, November 28, 2008 8:08 AM
To: Untitled
Subject: Re: EMI Receivers
With this sloppy terminology, rife in the commercial world, we are
raising a
generation of EMC engineers who have no clue why they do what they do, other
than they have to meet some legal requirement before marketing a product. It
is bad enough that I have seen in this forum otherwise well-regarded engineers
claiming that radiated emission requirements are there to protect all
electronics from interference, as opposed to radio receivers, which are the
sole victim protected by radiated emission limits. Non-antenna-connected
electronics don’t require that level of protection.
Happy Holidays!
Ken Javor
While Ken raises valid points, I think he is still defining interference too
restrictively. While many official limitations on radiated emissions have been
set to provide protection for receiving systems, this has only been the
historical precedent. There is no reason why a radiated emission limit cannot
also be used to protect non-receivers.
Actually, "non-receivers" is a bad term, because everything is a receiver. I
have seen many examples of "non-receivers" (things like A to D converters or
servo systems) which, either by poor design or construction, make fairly good
receivers.
It can certainly be argued that undesired responses to external energy should
be controlled by immunity requirements. Most of the time, that's true. But
COMPATIBILITY is a balance between control of emissions and ensurance of
immunity. You may go to extremes in both directions, or you can seek a balance
(typically defined by cost, weight, size, politics).
And that's why radiated emission limits can protect things other than
intentional receivers.
Ed Price
ed.pr...@cubic.com <blocked::mailto:ed.pr...@cubic.com> WB6WSN
NARTE Certified EMC Engineer & Technician
Electromagnetic Compatibility Lab
Cubic Defense Applications
San Diego, CA USA
858-505-2780 (Voice)
858-505-1583 (FAX)
Military & Avionics EMC Is Our Specialty
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