Some Guy said:
The point was that consideration is being made to allow cell phones to
be used while the planes are in flight. That intentional radiating
PED's are even being considered for in-flight use when so much hype
and concern is being given to the weak radiation potential of some
non-intentional radiators like am/fm radios.
Because, as has already been pointed out, of the
differences in emission characteristics (and specifically
the frequency ranges likely to be affected) of the two
classes of devices.
BTW, what is the potential of the local oscillators of small hand-held
LCD-screen TV's to overlap with aviation frequencies?
I believe they should be somewhat less than is the case
with an FM receiver, but they're still a bad idea for
the same reason. Note that the analysis of the likely
frequencies provided so far has dealt solely with the
first-order effects of the receiver's local oscillator; we
have NOT discussed harmonics or other unwanted
emissions.
The problem is most obvious with FM receivers because
the standard 1st LO frequency is 10.7 MHz, and the
top of the FM broadcast band is adjacent to the bottom
of the aviation band (108 MHz) - which means that
simply adding the LO frequency to standard FM
broadcast frequencies can take you instantly into overlap
with the bottom 10.7 MHz of the aviation band (and
unfortunately, that's where a lot of the radionavigation
systems within that band tend to be). But this does
not mean that receivers for other services would not
cause similar problems. VHF television covers
frequencies below and above both FM and
aviation (two bands, 54-88 MHz for channels 2
through 6, and 174 to 216 MHz for channels 7
through 13). It is certainly very possible that receivers
intended for these bands would emit in the aviation
band. Other adjacent services that may be of concern
include public-service and commerical communication
bands (i.e., police scanners) and the 2-meter amateur
band.
Bob M.