Let me further clarify the statement below.
Computer certifications permit each component to be certified separately
and assembled as a system. As long as all of the components which go
into the computer are certified individually, you can assemble them
together into a computer which is also FCC legal, as far as the
unintential radiation (FCC Class A and B computing device)
certifications go. This is somewhat simplified, but you get the jist.
The reason why this works is that each device is only adding a certain
amount of noise, and as long as the total quantity of rf noise doesn't
exceed a threshold, the computer is compliant.
On the Part 15 intential radiator rules it is significantly different.
This is because you are intending to transmit, and when this occurs you
aren't just looking at random noise which happens because of the way the
computer is put together... you are looking at a transmitter which must
work correctly in order to meet the emission limits, both in and out of
band. Because the limits are so tight, if you change an anteena you
may affect the in-band or the out-of-band emissions or both. If either
is out of spec, the equipment would not pass certification. Even
changing the type of antenna may make a transmitter not work correctly,
even if the gain is the same across the board. This is why the whole
system needs to be certified together. The FCC has loosened this up a
bit, so that the manufacturer can say that they tested it with antenna X
which is similar to antennas Y and Z and as such X Y and Z are all
certified. But this flexibility does not extend to the end user. They
have to use only antenna X, Y, or Z and not antenna A.
A certified radio card straddles both lines - as such it has been tested
for emissions both under Part 15 intentional and also unintentional
radiator rules. Both sets of "permissions" apply - it can be used, as
certified, to operate as a Part 15 intentional radiator - and it can
also be added to a certified computer system and comply with Class A and
Class B computing device for the unintentional emissions. Think of it
as two different devices - the radio part and the computer interface part.
Forrest W. Christian wrote:
Mike Hammett wrote:
Then why can I purchase a Netgear PCI card for my Dell desktop?
Because the Netgear PCI card has been certified both as a computing
device and a Part 15 intentional radiator - but only if it is used
with the antenna which the Netgear was certified with.
-forrestc
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