From: Robert Johnson [mailto:[email protected]] Sent: Wednesday, February 14, 2007 6:02 PM To: [email protected] Subject: Noise canceling headsets
On my last flight the flight attendant requested all electronic devices be turned off and specifically mentioned noise canceling headsets. The only real use I have for noise canceling headsets is for aircraft noise. I assumed these headsets were purely audio circuits. Is there some reason for them to be producing RF emissions? Is this just an uneducated paranoia about all things electronic? Is this just an attendant's opinion, an airline or FAA policy? The pilots use them, why not the passengers? Bob Johnson ITE Safety <http://www.itesafety.com> Bob: You answered part of your own question; the headsets are "electronic", most likely have a microprocessor to do the cancelling function, and thus have the potential to create radiated emissions. On their side, the devices are physically small (bad radiation efficiency) and very low-power. Against them, they have AD & DA conversion, and probably some digital noise and harmonic content. Your consumer-grade headset has probably not been found to be compliant with DO-160 or anything special related to an aircraft environment, so we don't really know how bad they might be. If you don't know, and I don't know, then who does? Is the aircraft crew competent enough to judge? The easy answer is to allow anything electronic onboard, or to allow nothing electronic. What would you do if you had 200 people, all loaded with multiple electronic devices, climb aboard your aircraft? If you saw a guy with a hand-held, 10 watt, multi-band transceiver, would you let him operate it in the cabin? Probably not. But would you make him remove the battery from his wristwatch? Probably not. So where along that continuum does your noise-cancelling headset fall? Besides, if the whole flight were being operated for your convenience, comfort and safety, then the plane would have more insulation, the engines would be quieter, and the seats would be bigger. And you would pay a lot more. Ed Price <mailto:[email protected]> [email protected] NARTE Certified EMC Engineer & Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (FAX) Military & Avionics EMC Is Our Specialty ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ - ---------------------------------------------------------------- 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
