I agree with Jim. The measurement uncertainty I mentioned is only for
the measurement chain. Product uncertainty usually swamps that. As you
would expect, it's all about the product. I currently work with robot
vacuum cleaners and their docks. No cables and battery powered is as
simple as it gets. I'm measured rack mount systems with 30+ cables, and
it's a nightmare. I would suggest discussing your product in detail
with the test house, or a consultant of your choice, to more accurately
evaluate your margin needs.
Brent DeWitt
On 7/8/2023 10:17 AM, Jim Bacher, WB8VSU wrote:
Brian, for margins it's not required by the standards. It is a
"Personal Preference". I have always used and recommended 6 dB for
prototypes / first production and 3 dB margin for production audits.
As Brent mentioned there is variation in measured levels between test
sites. However, your product in production will also have RF emission
variations.
All produced products need to be compliant, not just the one you
tested. How consistent are your production units? If they are very
consistent, then a lower margin might be Ok.
Jim Bacher
On July 8, 2023 12:41:10 AM Brian Gregory <brian_greg...@netzero.net>
wrote:
Hi there,
A question came up that I can't answer w/o a copy of Part 47.
Does the FCC report require Quasi-Peak (QP) data, or just Avg and
Peak. When do peak readings trigger the need to report QP? I'm
pretty sure Part 15 has AVG and QP limits listed.
Next was what sort of margin is expected in order to pass CE
emissions requirements (CISPR 16 or 32)? Memory serves that one
wants 3dB of margin, but memories can be imperfect!
"Colorado" Brian
720-450-4933
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