IIRC, the radio receiver ban dates back to when relatively inexpensive
aircraft band receivers (things passengers took on board, not the radios
the airplane was fitted with) were often regenerative/superregen and
thus interfered with aircraft communications if mis-adjusted (and were
often mis-adjusted by John Q. Public). After a few incidents where
passengers took radios on board to listen in to the aircraft
communications and inadvertently *prevented* aircraft communications,
all radio receivers were banned.
<http://en.wikipedia.org/wiki/Regenerative_circuit>
There is tremendous inertia in relaxing restrictions once in place,
especially where safety was once involved.
Best regards,
gvb
Claes Mogren wrote:
I call bullshit on this signal restriction. How come they've
successfully had wifi on planes without any problems? And I know that
people have their phones on all the time while flying and I've never
heard that it has caused a crash or even been noticed in any way. Can't
imagine that there's any GSM signal to pick up a 30000ft anyway when you
move at 800km/h.
Also, if GPS is bad for the planes, how come the US is going to use it
to navigate the planes?
(http://www.theregister.co.uk/2007/09/04/gps_satnav_air_traffic_for_america/
<http://www.theregister.co.uk/2007/09/04/gps_satnav_air_traffic_for_america/>)
Anyway, back to OpenMoko. I agree that it's good to have the option to
turn all wireless communication off on boot, with a timeout of 10
seconds or so. Default should be the same settings as you had when you
turned off though.
Regards,
Claes Mogren
On 9/4/07, *Richi Plana* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
On Tue, 2007-09-04 at 10:27 -0700, John Seghers wrote:
> Part of the process of receiving signals involves
heterodyning--basically
> mixing a received signal with lower intermediate frequencies (IFs) to
> amplify the desired actual signal, while making the carrier
signal something
> easier to work with. See http://en.wikipedia.org/wiki/Heterodyne
for a very
> basic description.
Fascinating. So "passive receivers" really aren't? Or are there classes
of receivers which are (no amplification or very sensitive pickups)?
Prolly off-topic, but I sure am curious. Are there no radar detectors
which don't give off their presence?
--
Richi Plana
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