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. > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
