[time-nuts] Boeing 787 GPS reception trouble

Dr. David Kirkby drkirkby at gmail.com
Mon Jun 2 12:48:51 EDT 2014


On 2 Jun 2014 10:03, "Tom Van Baak" <tvb at leapsecond.com> wrote:

> Now I have never had a problem with reception in the terminal, walkway,
or even while seated inside a plane. I figured the aluminum frame of the
plane was thin enough that photons at cell, GPS, and gamma frequencies
easily pass through the outer shell or the windows.

I do have quite a bit of data on that, having measured the attenuation both
in flight tests and on the ground. (I don't trust the latter anyway.) I
can't share it unfortunately.

But you should be aware of of how the systems in aircraft that allow one to
use a phone work. The cellular operators were keen that one could not cause
interference on the ground by a phone connecting to many base stations. For
this reason the planes incorporate a noise generator that raises the
background noise so that the phone cant hear any cell sites on the ground.
I would not expect that to be enabled below about 3000 m, but it is quite
possible that the noise generator was on.

I would not expect it to jam GPS frequencies,  but certainly those used by
mobile phones.

Dave


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