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  1. #21  
    Originally posted by cellxprt
    I understand the wireless part, I mean you would probably hang every cell tower for several states as your phone was looking for a signal.


    i don't think that is why they don't allow cell phones on airplanes
    This article has some conflicting info in it.

    The FAA says because of the interference to the plane's electronics and the FCC says it could occupy several towers on the ground.

    Except for Sprint it seems ... they operate on a different frequency than regular cell phones and Sprint doesn't interfere with the plane or the towers.

    In any event, it seems there is no evidence that PED's interfere with an airplane's electronic evidence.

    But, to be safe ... lets just keep 'em off ... we all need a little quiet time anyway.

    BTW ... I don't snore.
  2. #22  
    lol, ok i am big, but not really fat. i am 6'2" at almost 300lbs. those damn seats are made for some small A$$ people!!! i have to sit next to someone i know or the other person is in for a very uncomfortable ride. last time i accidently slapped the guy next to me with me elbow fell trying to get comfortable. but when you are big a lot of people forgive!!
  3. #23  
    Originally posted by tjd414


    This article has some conflicting info in it.

    The FAA says because of the interference to the plane's electronics and the FCC says it could occupy several towers on the ground.

    Except for Sprint it seems ... they operate on a different frequency than regular cell phones and Sprint doesn't interfere with the plane or the towers.

    In any event, it seems there is no evidence that PED's interfere with an airplane's electronic evidence.

    But, to be safe ... lets just keep 'em off ... we all need a little quiet time anyway.

    BTW ... I don't snore.
    Cell phones and any other electronic device can not interfere with the planes electronics. If this was the case then terrorists could simply hide some sort of high output jammer in a phone and could crash a plane by screwing up the electronics. Also their are so many frequencies being transmitted on earth from so many sources that the plane would never run. The reason you have to turn off your device during take off and landing is so that you pay attention to the flight crew if giving directions or for an emergency during take off and landing.

    Cell phones can light up multiple towers while airborn and you can get fined heavily by the FCC if you do this. This the reason cell phones can only be used while the doors are open on a plane to prevent a potential tower issue while the plane is in flight.

    You have to do what the flight crew says anyway, even if the justification is pure BS, or you may be locked away in a holding cell for a while when you land.
  4. #24  
    Originally posted by randyg
    i thought I was the only one that got stuck next to the flying flubber!! that wants you to put the armrest up so there fat rolls can rest on you instead of it!! not me, buy another seat fat-boy, i paid for this space.
    Hey, I'm 6' and 210 ... not small ... not big. Just because you buy two doesn't mean you get to keep two.

    When you check in, you can only have one seat, so your other seat goes to the next person on standby. And she's fat too, and won't stop talking about the new Star Trek!!!!! And you're stuck in the MIDDLE SEAT!!!!!

    Not that this ever happened to me ... it was, yeah, the guy in front of me ... yeah, him!
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    #25  
    cellxprt...i feel for ya big guy! i'm only 5'5", 145, brn hair, blue eyes...oh wait, wrong web site! anyway, as small as i am, i've been on planes where my knees are in the back of the seat in front of me and my hips touch both armrests, exactly how small can they make these seats before they're even too small for Ally McBeal??

    and while i'm going off topic slightly, i agree with lnichols, and here's how crazy this kind of mentality has gotten. i recently purchased a Mini Cooper S (DS/B for those in the know). There was a warning sticker regarding the use of cell phones while driving the vehicle, not for the reason of distraction, but because it could interfere with the drive by wire action of the accelerator! say what?? even if I didn't use my cell phone while driving my car, what about the other people out there driving and chatting, won't their phones interfere with my car too? could this be anymore absurd??

    while i don't pretend to understand how an airplane works, it seems that if a simple little cellphone signal could cause the plane to lose control (or whatever), what about all the other signals out there in the air that they can't control. what if some kids rc airplane control suddenly took over a 747? it's just crazy talk, that's all.
    a dirty mind is a terrible thing to waste
  6. #26  
    Cell phones and any other electronic device can not interfere with the planes electronics.
    Actually, they can and do.

    I have personally seen the autopilot in a commercial flight affected by a laptop computer. It's not a matter of the box or processor being affected, but the EMI created from the laptop can affect signals running through wires routed in the airframe structure. The wire harnesses in these commercial aircraft are not shielded to provide that type of EMI protection.
  7. #27  
    Originally posted by SprintTreo600
    What flight was this on tdg414...ive been using my 300 with wireless off for awhile...they told me as long as wireless is off?



    why is it that they have you turn your phone off?
    US Airways, Palm Beach to Pittsburgh ... 'cause they said it interfered with the plane's electronic equipment.
  8. #28  
    Originally posted by randyg
    There was a warning sticker regarding the use of cell phones while driving the vehicle, not for the reason of distraction, but because it could interfere with the drive by wire action of the accelerator!
    Check this: http://www.marcspages.co.uk/articles/0112.htm

    It's a reprint of a 3 years old article talking about the same type of problem. I believe that Lexus once issued a recall (2-3 years ago ???) because "Cell phone communication could trigger unexpected braking !".

    Anyway, the comments after the article debunk some of that but still, manufacturer are putting new warnings, obviously !
    Since people have problems with my Einstein quotes, I will now quote my true hero: Homer Simpson.

    "Doh !'
  9. #29  
    I use mine on flights and about 1/15 flights I have a paranoid flight attendant who makes me put it away.

    The guy who commented about the hanging of cell phone towers across the world. Do you know much about RF? Airplanes flight 6 miles above the ground and cell phone towers orientation generally points downwards.

    The RF from your cell phone would definitely not be strong enough for the radio receiver to pick it up. The towers have strong receiver sensitivity, but not that strong.
  10. #30  
    Originally posted by tjd414


    US Airways, Palm Beach to Pittsburgh ... 'cause they said it interfered with the plane's electronic equipment.

    BS....i took us airways from boston to dallas and used my treo the entire time when the people came by with food all said was that the phone can't be transmitting any signals...i told them the wireless mode was off, and they said that it was fine!
    Treo 300, Treo 600 - Sprint

    I dream in code and TCP/IP sequence numbers.
  11. #31  
    American Airlines once from Dallas DFW to Los Angeles LAX I had some ***** tell me the same interferrence thing. I showed her my business card (I work with RF for a living and work with the FCC). She didn't give half a crap, and told me if I didn't turn it off that there would be problems.

    So I turned it off.
  12. #32  
    Originally posted by BrianV
    I use mine on flights and about 1/15 flights I have a paranoid flight attendant who makes me put it away.

    The guy who commented about the hanging of cell phone towers across the world. Do you know much about RF? Airplanes flight 6 miles above the ground and cell phone towers orientation generally points downwards.

    The RF from your cell phone would definitely not be strong enough for the radio receiver to pick it up. The towers have strong receiver sensitivity, but not that strong.
    I understand what you stated in your post, and since I am not in any way, shape, or form an expert on RF and I will readily admit as much. I dial, press the send button and it works ... I'm a happy guy.

    The FCC (you said, in your last post, you worked with them) in this article claimed just the opposite. Cell phones would interfere with towers on the ground, in fact, they would interfere with several towers at once. Now, I am not saying the government always knows what it is talking about ... but there is just a tad bit of conflict.

    All in all, you being a business person (I assume), I would have to go with your read on the situation.
  13. #33  
    Well I don't work for the FCC, my company has a relationship with them, as we get nearly all of our products approved, and my product designs have to fall within the limits of FCC guidelines (RF power output, etc.)

    I have turned my cell phone on in airplanes. I honestly think the interference with electronics and communications is minimal if anything. In fact they NOW let you use your cell phone the minute you're on the runway, not at the gate (I'm sure their electrical and communication systems are still running at that point). Even when coming in for a landing in Los Angeles I do not get signal at nearly any point until we're VERY close to the ground. I don't get signal until quite a bit after the landing gear goes down.

    As far as what I know about RF.

    35000 miles in the air is 6-7 miles in the air. The antennas are pointing down towards the ground (sector panel antennas at a 30-45 degree angle). Cell phones in digital service output 600mW (~28dbm). The towers themselves put out 30-40 Watts I believe. The cell phone antenna is OMNI directional with vertical polarization. Thus, the signal emitted will travel horizontally out of the phone at maybe a 75 degree beamwidth. It will take a long time for that angle/beamwidth the hit the ground 7 miles down.

    We can use geometery to figure this out.

    Sin(15) = 7miles / X miles
    X = Distance to ground, the long segment of a right triangle.

    X miles = 27 miles.
    The signal would have to travel 27 miles to hit the ground at a 75 degree angle.

    Without factoring in antenna polarization, 27 miles is a bit too far (including making it out of a METAL plane's fusolage).

    I'll read this article, but Sprint uses a 1900 MHz band, and that's pretty high. If it was a lower band I could fathom the idea, but not at 1900 Mhz. I don't know that much about CDMA RF though, I don't know how it modulates data.
  14. #34  
    Just started reading the article. It was just after take off, so I can see that the cell phones would have connection to the ground at early points of the flight.

    Also, during 9/11 people made several cell phone calls in the planes, but all of the planes were well under 500 ft in altitude.

    Again, I'm no expert on cell phone RF, but how a cell phone makes a fire detector go off sounds like a design flaw if you ask me.

    Also, anytime an airline company can find an excuse they'll USE it. In the USA there's the FAA and other investigative parties that investigate crashes. I trust their results, but I don't know about this one.

    Valujet crashed because of a luggage hold fire caused by O2 canisters that didn't have safety pins installed. If Valuejet didn't have the FAA prove they weren't following policy, they may still be in business today, and they would've much preferred writing it off to cell phones.

    Bringing a microwave over onto an airplane and firing it up would probably be a bad move, but cell phones are isolated to a minimal frequency range and I'm 100% positive airliners are using licensed bands that are not cell phone bands. RF devices do not interfere with each other when they're on different frequencies.
  15. #35  
    Originally posted by BrianV
    Just started reading the article. It was just after take off, so I can see that the cell phones would have connection to the ground at early points of the flight.

    Also, during 9/11 people made several cell phone calls in the planes, but all of the planes were well under 500 ft in altitude.

    Again, I'm no expert on cell phone RF, but how a cell phone makes a fire detector go off sounds like a design flaw if you ask me.

    Also, anytime an airline company can find an excuse they'll USE it. In the USA there's the FAA and other investigative parties that investigate crashes. I trust their results, but I don't know about this one.

    Valujet crashed because of a luggage hold fire caused by O2 canisters that didn't have safety pins installed. If Valuejet didn't have the FAA prove they weren't following policy, they may still be in business today, and they would've much preferred writing it off to cell phones.

    Bringing a microwave over onto an airplane and firing it up would probably be a bad move, but cell phones are isolated to a minimal frequency range and I'm 100% positive airliners are using licensed bands that are not cell phone bands. RF devices do not interfere with each other when they're on different frequencies.
    I was about to bring up the example of the cell phone calls during 9/11. Are you sure they were all below 500ft? Certainly as they came close to crashing, but the one that crashed in PA, for example, the airline crew member called more toward mid-fllight, I thought (since she spoke for a while to officials).

    Lastly, WHY did you turn on your phone in mid-flight?? Good thing they don't have detectors for that sort of thing!! ;-)
  16. #36  
    I remember on my old Palm VII being able to get signal in flight. I'd have to be close to a window, turn my antenna flat so that the signal will beam towards the ground and I would get 2 to 3 bars of connection as long as I was above populated area (that was in 99, coverage was pretty spotty.) I was switching towers pretty fast but I was using it as a poor mans GPS: I had a small PQA app that would return the location (zip code and city) of a the tower I was talking to !

    Additionally, I forgot to turn my cell phone off several time while flying across the country (NJ to LA) and twice my cell phone rang with a voice mail as I got closer to civilization (usually as we flew above Las Vegas ! )

    So, I've seen it happen !
    Since people have problems with my Einstein quotes, I will now quote my true hero: Homer Simpson.

    "Doh !'
  17. #37  
    I spoke with a coworker about the cell phone at 9-11, he said the Penn one was higher. We both feel it was definitely using an analog service, as they output 6W in analog.

    The Palm story to me is incredible. I definitely think putting the antenna in the proper orientation is definitely necessary. I don't know what cellular network those Palm's used. 800 MHz analog would most likely not have a problem getting to the ground.

    I've left my phone on for the entire duration of a flight, only since I got my treo do I turn it off (due to battery drain, etc.). To be honest, I have 0 belief that there can be interference, there's some other reason behind it (causes too much commotion and disturbance, etc)
  18. #38  
    As far as Palm goes, I can swear it is true. It wasn't working really well but I did get it to work. I believe they were using the CDPD on the backend of ATT TDMA network... Now, remember that this was a PQA, sending a few bytes of text. I would send a request, get a response... sometimes... It wasn't a continuous update. Same thing with the cell phone: I'd get the voice mail ring, never could place a call though. Additionally, I tried running PQAs from the plane again when I moved from my Palm VII to a Samsung I300 and it never worked there.

    I'm sure *some* devices could create interference (ie: the motorola-Gordon-Gecko-Wall-Street-Brick for instance) and airlines don't want to train people on what is allowed/no allowed. Additionally, I agree that they could also do that to prevent people yapping away carelessly during 6 hours flight, push the use of their own airfones (discontinued on American Airlines I think though), etc... Last, the list in the magazine about what is allowed and what is not contains a number of other devices (Radio, TVs, GPS, etc...) which I consider only RECEIVER, thus accessing frequencies already being broadcasted, even if nobody uses them (Zen question: if nobody watches over the air TV, does the tower stop emitting ? )
    Since people have problems with my Einstein quotes, I will now quote my true hero: Homer Simpson.

    "Doh !'
  19. #39  
    Originally posted by BrianV
    I use mine on flights and about 1/15 flights I have a paranoid flight attendant who makes me put it away.

    The guy who commented about the hanging of cell phone towers across the world. Do you know much about RF? Airplanes flight 6 miles above the ground and cell phone towers orientation generally points downwards.

    The RF from your cell phone would definitely not be strong enough for the radio receiver to pick it up. The towers have strong receiver sensitivity, but not that strong.
    I made the quote about the Cell towers and yes I know about RF. I have an EE degree and have had Electromagnetic field theory classes and I have worked for a fixed wireless telecom provider. I have also done RF coverage analysis studies before for military applications.

    Cell phones have more limited coverage on the ground due to the obstruction of the earth, buildings, etc. The curvature of the earth can cause some issues but at a couple of miles this is not a major factor. While the cell towers due have directional antennas (usually 120-degrees coverage pattern) with a downtilt of some sort they will still transmit upward some. Cell phones have an omnidirectional antenna that transmits at 360 degrees. When you are in a plane the only obstruction is the plane itself so the signal will travel much farther than from the ground since it will always have line-of-site to the tower. While the phone may not see the tower, the tower could/can see the phone, even if the signal is very faint. And while some planes do fly at 30,000+ ft, their are still many commercial flights that fly at 20,000 to 25,000 ft, which is only 3 to 4 miles.

    If this were not an issue, then the FCC would not have regulations, and fines to prevent/penalize for this.
  20. #40  
    Originally posted by lnichols


    I made the quote about the Cell towers and yes I know about RF. I have an EE degree and have had Electromagnetic field theory classes and I have worked for a fixed wireless telecom provider. I have also done RF coverage analysis studies before for military applications.

    Cell phones have more limited coverage on the ground due to the obstruction of the earth, buildings, etc. The curvature of the earth can cause some issues but at a couple of miles this is not a major factor. While the cell towers due have directional antennas (usually 120-degrees coverage pattern) with a downtilt of some sort they will still transmit upward some. Cell phones have an omnidirectional antenna that transmits at 360 degrees. When you are in a plane the only obstruction is the plane itself so the signal will travel much farther than from the ground since it will always have line-of-site to the tower. While the phone may not see the tower, the tower could/can see the phone, even if the signal is very faint. And while some planes do fly at 30,000+ ft, their are still many commercial flights that fly at 20,000 to 25,000 ft, which is only 3 to 4 miles.

    If this were not an issue, then the FCC would not have regulations, and fines to prevent/penalize for this.
    If the phone can't see the tower, then the tower can't see the phone. Even though the tower has WAY more power, it's added power increases its receiver sensitivity. Thus, it can see or HEAR more faint signals. An RF signal doesn't ever really die, it just becomes so weak that a receiver can't make anything out of it. A very sensitive receiver can pick it up. A good example is the space shuttle. The space shuttle has a moderate sized antenna/dish on it, while the ground based unit has A LOT of power, and its power makes up for the weaker space shuttle setup. RF waves can't ride on the antenna waves from a larger antenna, all they can do is be picked up more easily.

    I just honestly feel that with vertically polarized antennas on phones at 7 miles up, even with line of sight, the signal would be too faint for the cell phone tower to hear, but like I said I'm no cell phone RF guy, nor do I attempt to make phone calls or browse the internet in the air. Most of the places I fly over don't have cell phone coverage anyways, and due to the speed of a plane you won't stay in a coverage area for very long.

    Thanks for the explanation though.
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