At 13:05 21/03/2001 -0500, Rosen, Brian wrote:
Well, but
Most PC designs use phase lock techniques which keep external
signals way below the CPU operating frequency
The usual multiplier is in the single-digit range. That's why I said "some
hundreds of megahertz". And don't forget the harmonics....a 100-MHz square
wave (or reasonable facsimile thereof) has a major harmonic component at
300 MHz.
There are legal limits for radiation; most laptops and all
PDA devices are "Class B" which is a pretty low level.
The real issue I suspect is that there is no practical way to test
what the effect of a whole planefull of "at-the-limit" devices do
to the plane's systems. It is very reasonable to design the avionics
to be hardened against this sort of thing, but the older planes wouldn't
have such avionics.
control systems on older planes (pre-1970) are actually more robust,
because they use a lot more analog and hydraulics rather than avionics.
nav systems are another matter, of course.
I expect we will see some lessening of the rules as the experience
and turnover of the airframes proceeds. We already have the
"mobile use okay until pushback" which is a real change.
hasn't arrived in Europe yet, unfortunately.
--
Harald Tveit Alvestrand, alvestrand(_at_)cisco(_dot_)com
+47 41 44 29 94
Personal email: Harald(_at_)Alvestrand(_dot_)no