Following the pointer from the active 777 topic, for those thinking about electronic interference. There may be no interference at all from one source in one mode, or in any of its modes.
Combining two variable sources gives an inordinate number of possible combinations.
Combining all the sources passengers may have active at any moment gives in inestimable number of combinations.
What do we know about combining a great many waveforms? On a two-dimensional surface, quite a bit, although this work has become a worry only very recently because it explains a problem long considered a myth, until photographs and satellite instruments show it happens:
http://www.ams.org/mathmedia/archive/01-2003-media.html
" BBC Two, on November 14, 2002, aired a program on this phenomenon and its recent mathematical analysis. Freak waves, also "rogue waves," "monster waves," are extraordinarily tall and steep waves that appear sporadically and wreck havoc with shipping. One is suspected to have washed away the German cargo München which went down with all hands in the midst of a routine voyage in 1978. More recently, the cruise ship Caledonian Star was struck by a 30m wave on March 2, 2001. The standard analysis of ocean waves predicts a Gaussian-like distribution of heights; extreme heights, although possible, should be very rare - a 30m wave is expected once in ten thousand years, according to the BBC. But these waves occur much more frequently than predicted. The program focused on new methods of analysis, and on the work of the mathematician A. R. Osborne (Fisica Generale, Torino). Osborne has applied the inverse scattering transform, which he describes as "nonlinear Fourier analysis," to the time series analysis of wave data. He conducted simulations using the nonlinear Schrödinger equation and found near agreement with the standard analysis, except that "every once in a while a large rogue wave rises up out of the random background noise." His paper ... gives an example of such a simulation:
http://www.ams.org/mathmedia/images/wavetrain.gif
See the spike? Put the spike into your onboard electronics. There will be a spike strong enough to overcome the specified sensitivity protection, somewhere in 3-dimensional space inside the aircraft, at some point. Most of them won't coincide with anything that will interpred the spike as a signal. Some of them will. Some of the software won't reject that as an incorrect signal.
On a two-dimensional surface, the ocean, such a spike (rogue wave) can break a long oil tanker in half. The tanker design assumes there are no such waves -- they weren't observed when the designs were established and nobody's tried to reinvent the oil tanker to build one capable of surviving these events. They lose a few, cost of doing business -- until now nobody could do the statistics, they didn't believe rogue waves happened!
The Japanese had a term for this long ago, in a very dense population with a lot of electronics and electrical gear and little in the way of shielding -- "electronic smog."
The first deaths from unexpected activation of electronic equipment due to this were reported over 20 years ago.
http://intranet.cs.man.ac.uk/Study_s...P10070/KR_real
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A series of mysterious deaths in which industrial robots suddenly attacked and
killed humans is being investigated in Japan, news reports said yesterday. Ten
people have been killed by robots in the last eight years. In four cases,
operating errors were blamed. In the other accidents, the robots suddenly
started working for unexplained reasons, according to reports. Witnesses
listed a number of cases in which the robot suddenly stretched out its
mechanical arms, killing its victim. Experts plan to test a theory that
electromagnetic waves in factories have been responsible for setting off the
sensitive computer mechanisms in the robots.
[We had previously documented the 1981 Kawasaki case, and noted reports of at
least four more (and possibly as many as 19) robot-related deaths.]
http://catless.ncl.ac.uk/Risks/4.91.html#subj1.1
CHIPS ARE DOWN OVER ELECTRONIC POLLUTION
The Guardian, 26 May 1987
"Lindsay F. Marshall" <lindsay%
[email protected]>
Japan is engulfed in an "electronic smog" which has caused deaths and injuries,
and jammed an airport radar system, according to recent findings.
Electronic smog occurs when electromagnetic waves from equipment like personal
computers and electronic game machines "escape" and trigger other machines. An
electromagnetic wave can also be caused by a mere spark. An electric spark
from a crane operating in a valve plant set off a lathe-operating robot in
1982 killing an assembly-line worker.
http://catless.ncl.ac.uk/Risks/2.42.html#subj1.1
Date: Mon 14 Apr 86 09:19:46-PST
From: Ron Cain <
[email protected]>
-----end excerpt------
Remember -- the more signals you have, the more they will overlap, and the energy in the waves is additive so you _will_ get 'rogue' spikes of very strong signal that come from no identifiable individual source -- they come from the interaction of many signals that is momentary and not reproducible.
And we're at a sunspot minimum right now, so you can't blame it on sunspots. In a few years, though, those will be adding to the effect.