In ancient times, the FCC required we perform RE testsby manipulating
peripheral and cable placement to maximize emissions; our tech at Tandy
was fiendishly clever, but we had to draw the line short of wrapping
cables around the (CRT) monitor.
Lots of stories...
Cortland Richmond
On 9/1/2017 8:10 PM, Brent DeWitt wrote:
I agree with Jim that your calculated measurement uncertainty is the
minimum margin that one should apply. This could be doubled by
assuming the second assessing laboratory had the same uncertainty, but
in the opposite direction! In practice, I believe that the products
cabling, and therefore the setup uncertainty, may become dominant.
When I perform radiated emissions measurements on a product with
multiple cables, I observe a wide span of potentially “interesting”
emissions on the SA/receiver, then grab the entire bundle of cables
and simply toss them randomly. If things wiggle by a couple of dB, I
move on. If things swing by ten dB, I’ve got my work cut out for me
to maximize and I advise the customer to take a much more generous
approach to their margin requirements.
Brent G DeWitt
Milford, MA
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