While the test setup and study appears to be suspect, I cannot argue with
the recommendations coming out of it:
"......co-ordination of electronic emission standards...." (always a good
thing in any field of endeavor)
".....monitoring of on-board radio emissions by flight data recorders. "
(sometimes planes are lost for no apparent reason, more data wouldn't hurt)
Bob Heller
3M EMC Laboratory, 76-1-01
St. Paul, MN 55107-1208
Tel: 651- 778-6336
Fax: 651-778-6252
=========================
----- Forwarded by Robert E. Heller/US-Corporate/3M/US on 03/03/2006 02:28
AM -----
Pat_Lawler@condor
dc.com
Sent by: To
[email protected] [email protected]
cc
03/02/2006 03:37 Subject
PM Re: Electronic equipment on
commercial flights
I question the test setup used for measuring the signals. The measurement
antenna was inside the cabin area, in immediate proximity to the
interference source, and far away from the victim - the aircraft receiver
antennas located on the outside of the aircraft.
The study would be more valid if the equipment measured the interference
field in the vicinity of the antennas, or if it measured the background
noise seen at the coax coming into the receivers.
I understand if the FAA or airlines wouldn't like this kind of testing
during normal flights. This should be easy to do on the ground, too.
There should be more than enough test beds in the southwestern U.S.:
http://www.mojaveairport.com/Inlay_Pages/New_inlay_pages/storage_IL_new.htm
Load it up with old laptops, discarded cellphones, used CD players, and
test away!
Pat Lawler
EMC Engineer
Condor DC Power Supplies
Fred Townsend <[email protected]>
Sent by: [email protected]
03/02/2006 12:20 PM
To: Nick Williams <[email protected]>
cc: [email protected]
Subject: Re: Electronic equipment on commercial flights
The information is indeed interesting. I also find it is interesting the
study did not cite any actual interference. They used an onboard
spectrum analyzer to verify people actually used, or tried to use their
cell phones. If we set, as a standard, any level of potential
interference, then the airplane should never fly because of the
potential of the airplane to interfere with itself from its own
navigation and communications systems to say nothing of digital fly by
wire. What about the 'glass cockpit'? It's full of digital devices in
close proximity! What about that local radar that paints the airplane
with very high level microwaves just as the plane is landing. Shouldn't
we be focusing on immunity standards for the cockpit? After all, mother
nature puts out signals too. Ever catch a lightning burst on your
spectrum analyzers?
Second related subject: The cell phone design depends upon frequency
reuse and hand-off from cell to cell. This works well when the airplane
is on or near the ground. Both of these techniques are defeated when the
radio is airborne, particularly at high altitude. The same radio is
seen by multiple cell sites causing multiple responses. The tracking
system will be confused by multiple reports of the same CID. This
reduces the available frequencies as well as confusing the cell phone
itself. This is going to result in dropped calls for all users. Seems
like the system needs to automatically detect airborne operation and
disable the CID.
Fred Townsend
Nick Williams wrote:
> I know quite a few subscribers to this group will be interested in this:
>
>
http://www.theregister.co.uk/2006/03/02/aircraft_mobile_phone_risk_study/
>
> Regards
>
> Nick.
>
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