FCC Rules do address this issue:
FCC Rules Part 15, Section 15.31 (k) discusses "composite systems"
which incorporate different devices contained in either a single
enclosure or in separate enclosure connected by wire or cable. Among
other things, this paragraph states "In no event may the measured
emissions of the composite system exceed the highest level permitted
for an individual component". Hence, a device cannot be certified or
verified as class B if tested in a class A composite system, because
the composite system will exceed the class B limits. It would also
follow that a device cannot be verified as class A unless the
composite system in which it is tested meets the class A limits.
Jim Hulbert
Pitney Bowes
______________________________ Reply Separator _________________________________
Subject: Re: Peripherals
Author: <[email protected] (Scott Douglas) > at SMTPGWY
List-Post: [email protected]
Date: 9/1/98 8:36 AM
Gary,
I have had my problems with support equipment and peripherals also. And,
having used a lot of big name products, mostly computers, etc., I was
surprised at how many of them failed when my product was turned off and
theirs was left running. It is quite common for test house guys to say "
Oh, that's the host, we'll ignore that one". I finally got to the point
where I put them outside the test environment, i.e. below the floor or
outside the shield room. I do this because I don't sell them and figure
that if I run self test mode and don't see the problem, then it is either
the other guy's stuff or my I/O. If it is my I/O, I will fix it. If it is
the other guy's stuff, I leave it alone. I can't / won't fix their
non-compliant equipment, don't have either the time or money to do so. I
did eventually find a quiet PC and monitor which I guard with my life. I
have even coerced the software guys into making their latest stuff play
with my older PC so I can keep using it.
I can't point to the reference you are asking for. It seems to me that if
the support / host equipment is required to be on the table during test,
then the entire thing must comply. It can be difficult to point the finger
at one piece and say that it is the source of the problem, especially on
the immunity side. If you try several different pieces of support
equipment and the "system" continues to fail, it probably is within the
common unit, i.e. your product. If you find that changing the support
equipment can make the "system" pass, then either you have a marginal
product or a too-sensitive support equipment. In this case, you have a
decision to make, and a tough one at that. Sorry I am not more help on
this one.
Regards,
Scott
[email protected]
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