Cell Phone Jamming On Airplanes - Page 1
Forum section: electronics / general

author: Undweeber
author_rank: Regular Contributor
timestamp: February 04, 2015, 03:42:36 am
content: Hey everyone, has it occurred to anyone that either airports or airplanes themselves have cellphone jammers?I usually fly from JFK International in NYC, and whenever I have some last minute calls, while people fill up the plane, the com will cut all of a sudden, but not disconnect, instead I hear a terrifying noise as if someone is burning and breathing heavily, as a matter of fact the first time I heard it I was terrified because I knew my dad was driving while talking to me, I tried calling back, but I couldn't connect even though I had signal, anyways i reached him back and he was fine.I am upset with how hypocritical FCC is, I understand the terrorist threat and have nothing against that implication, but to disallow jammers altogether for the general population and punishing people who essentially do the public service is a bit daft in my opinion. Nobody in their right state of mind would spend $500 then purposely, sinisterly, jam 911 signals for prolonged periods of time ignoring emergencies as they take place within few feet of you, which is an effective pocket jammer range..Any opinions on what I wrote?

author: Undweeber
author_rank: Regular Contributor
timestamp: February 04, 2015, 04:06:34 am
content: whats there to troll about, i just want to know about peoples experiences regarding jammers

author: Psi
author_rank: Super Contributor
timestamp: February 04, 2015, 04:09:02 am
content: Unless people in the USA are still using analog cellphones I don't see how this can happen. All you would get is a dropped call and maybe a very short burst of digital noise

author: wraper
author_rank: Unknown
timestamp: February 04, 2015, 04:09:48 am
content: Opinions? LOL. GSM/3G cannot be jammed in the way that some noise appears in the sound.

author: Unknown
author_rank: Unknown
timestamp: February 04, 2015, 04:12:46 am
content: My opinion is that it's doubtful. Jammers will result in the call being disconnected on a digital network as either the handset or tower has stopped receiving data or is receiving corrupt data.I have on rare occasions experienced "garbled" audio when connecting a call only to call back and have it fine. On further reading it may be something to do with cell hand-over to/from microcells and a timing mismatch in the audio codec. It has been a widely reported problem with calls made to or from Apple iPhones apparently.You may be connecting to a microcell inside the airport terminal that could be intermittently playing up or the additional bodies in the plane is enough to cause your signal level to drop below a certain level to start causing issues.In any case, if there was a reason for law enforcement agencies to block mobile calls, they have the power to shut down parts of the mobile network through the carriers (at least in Australia they do). Using jammers just seems like so much extra effort, equipment and cost.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 04, 2015, 04:30:49 am
content: This seems extraordinarily unlikely. Airports brag about adding extra "micro-cell" coverage to make cell service MORE reliable in their buildings.Seems more likely that the OP's phone is dying and needs replacing.

author: Undweeber
author_rank: Regular Contributor
timestamp: February 04, 2015, 04:34:39 am
content: @Halon @Richard Crowleythat makes sense, but when it happened to me I was using brand new international Galaxy S3, I didnt lose the signal and when i kept claling back i did eventually reach the other party.. hm.. and I haven't experienced that with my iPhone 5s and I flew last month, but my mom on iphone 3gs did experience it@Psi @wraperwell thats where the hole is in the story, I was thinking that too, but maybe they use something more sophisticated than some china made analog jammer, maybe its just some sort of scrambler, maybe they bend the rules of FCC and dont actually jem the signal but instead do what Halon said, and purposely offset it, that happens all the time and multiple times per "boarding" and only inside the airplane, that never happens to me anywhere else and ive had iphones and androids

author: Unknown
author_rank: Unknown
timestamp: February 04, 2015, 04:45:20 am
content: I still think the use of any such jammer is very unlikely. What possible gain do 'they' get out of it? Seems like wasted expense for little to no gain and increased consumer frustration.Don't forget just because your phone is indicating you have signal, doesn't necessarily mean it's any good. You might be on the fringe of an acceptable signal-to-noise ratio. (See:http://en.wikipedia.org/wiki/Received_signal_strength_indication)I don't think there is anything sinister going on here at all. It's either a hardware issue somewhere or a signal integrity issue (probably the latter). You'll probably find the fuselage of the aircraft and surrounding structures will be attenuating the signal noticeably as well. I remember when the Millennium trains in Sydney first came out, mobile signal was horrible, but as soon as the carriage doors opened, it jumped up to full reception again. I don't know if the glass they were using was metallised or something?

author: wraper
author_rank: Unknown
timestamp: February 04, 2015, 04:46:01 am
content: Quote from: Undweeber on February 04, 2015, 04:34:39 amTo do so you need secret agency capabilities. You need to be man in the middle between the base station and mobile phone. i.e. imitate the base station on your end and imitate your phone for the base station. And that is not trivial at all. Signal is encrypted first of all. So you need to decrypt it, jam the sound data, encrypt again and send it to the phone to achieve what you are describing.

author: Undweeber
author_rank: Regular Contributor
timestamp: February 04, 2015, 04:52:36 am
content: @Halon @wraperso could it be that the "base stations" the airports brag about, themselves do not receive good signal? Consecutively i receive "good signal" to the crappy airport base station, but that station does not communicate with the actual tower, and instead feeds some crappy feedback into my line?

author: Unknown
author_rank: Unknown
timestamp: February 04, 2015, 04:56:38 am
content: Quote from: Undweeber on February 04, 2015, 04:52:36 amNetworks won't provision cells without proper testing. Also microcells will usually be connected via cable or fibre into the network.

author: SeanB
author_rank: Super Contributor
timestamp: February 04, 2015, 05:01:33 am
content: Most likely an overloaded cell, that is trying to send too much data over a bandwidth limited connection to a switching station is simply dropping packets and this is appearing as noise on the call. Very common in high call density situations.

author: Undweeber
author_rank: Regular Contributor
timestamp: February 04, 2015, 05:02:56 am
content: @SeanBoh wow cool that actually makes sense!offtopic questiondo you by any chance know how long does it take for the connection to be lost once interrupted with a jammer? or is it immediate? because im under the impression that there are some seconds when the phone/tower try to reconnect, i might be wrongthanks for the input guys

author: Unknown
author_rank: Unknown
timestamp: February 04, 2015, 06:03:33 am
content: Quote from: SeanB on February 04, 2015, 05:01:33 amCells don't "overload". They employ very strict quality of service (QoS). Once they reach capacity, they will reject further calls and/or handoff to another nearby cell. Likewise if a cell is already at capacity and a higher priority call is attempted (for example an emergency call) it will bump off a call of lower priority or use reserve capacity to service such calls.If the connection between a base station and a network switching station experiences an issue or a disconnect, that cell is very quickly taken offline. Handsets connected to that base station will experience a very brief interruption before re-registering with a nearby tower.Quote from: Undweeber on February 04, 2015, 05:02:56 amThat depends of how the carriers have configured their equipment and the cause of the problem.There will be a pre-set timeout period before a call is dropped. If the base station experiences a few corrupt packets here and there it might be configured to be a bit more forgiving and "wait" for the signal to improve. However if it receives no response at all from the handset or continuous corrupt packets, the call is dropped almost immediately and the channel is released. You can test this yourself to some degree: Make a call between two phones and pull the battery out of one mid-call, see how long it takes for the call to drop.

author: LabSpokane
author_rank: Super Contributor
timestamp: February 04, 2015, 06:30:04 am
content: Do you think that being inside a large, radio-reflective metal tube could have anything to do with the reception issue?! I know that secret government conspiracies are vastly more entertaining, but there is a simple reason that the airplane's antennas are located on theoutsideof the fuselage.

author: Unknown
author_rank: Unknown
timestamp: February 04, 2015, 06:40:25 am
content: ... or you have an Apple iPhone and you were holding it "wrong"

author: G7PSK
author_rank: Super Contributor
timestamp: February 04, 2015, 04:32:48 pm
content: It could also just be that the pilot was testing his HF transmitter which bled over into the audio section of the phone, the digital side may reject the interference but the analogue audio wont.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 04, 2015, 05:44:10 pm
content: Note that at least in the USA, the FCC is proposing rules that would permit use of cell phones (voice, text, and data) while in-flight.It would be up to each airline to set their own policy about use of wireless devices on board their aircraft.http://www.fcc.gov/guides/wireless-devices-airplanesSo there does not appear to be any technological barrier to simply using cell phones on board.To be sure, even though they always tell us to turn off (or "airplane mode") wireless devices,you know that there are people who forget, or whose phone is in their purse or jacket pocket in the overhead bin, etc.So I suspect that most planes are already flying around with active cell phones operating.And, of course, there are an increasing number of flights/craft which have built-in wi-fi service.If a carrier would be discovered to be jamming, blocking, or even disallowing cell phone use,they would quickly become unpopular with their customers for such customer-vicious policies.

author: janoc
author_rank: Super Contributor
timestamp: February 04, 2015, 05:51:11 pm
content: Quote from: Undweeber on February 04, 2015, 03:42:36 amYou do realize that the phone use in flight is forbidden in order to protect from possible interference with the plane systems, right? (even though the rules are being relaxed now). Now adding ajammer producing the same signalsat a much higher power level needed to overwhelm the phones would certainly solve that problem, what a brilliant idea!Quote from: Undweeber on February 04, 2015, 03:42:36 amYou are either clueless or a troll. Or both.

author: Unknown
author_rank: Unknown
timestamp: February 04, 2015, 05:59:21 pm
content: Quote from: janoc on February 04, 2015, 05:51:11 pmYeahhh... that's not why they are banned by the airlines. In fact it's not even illegal. However causing a disturbance or disobeying the reasonable direction of flight crew is. I make the point again that if it's good enough for the pilots to use their phones on-board aircraft, then it's good enough for me.It's the same sort of scary nonsense that make people believe that using a transmitting mobile phone whilst filling a car with petrol is dangerous (again, not unlawful). There has never been a single case of RF from a mobile handset causing a fire at a petrol station, anywhere in the world.

author: SeanB
author_rank: Super Contributor
timestamp: February 04, 2015, 06:32:04 pm
content: RF from CB users with a kilowatt mobile rig however........In any case at an airport you do have a very large, very high power adjacent channel transmitter, which will aim a very high power 50kW plus beam of energy into all spaces every few seconds as it rotates. While a cellular base station might have 40dB of adjacent channel rejection it will not like having a massive input to reject every few seconds. it is a gamble if your slot is in the time when it is both aimed close to your location and is emitting a chirp that has a harmonic on the cellular band that desensitises the phone or the base station for a few moments.If I put an antenna on the roof ( standard UHF TV antenna, and point it correctly) I can get the reflected images from the primary RADAR at the local airport 30km away, using just a TV tuner and either a polar display or a PC sound card.

author: Undweeber
author_rank: Regular Contributor
timestamp: February 04, 2015, 06:35:43 pm
content: Quote from: janoc on February 04, 2015, 05:51:11 pmokay you seem to have figured it out, congratsthank you for your input guys, i can see the picture now

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 04, 2015, 06:48:38 pm
content: Yes, I think SeanB makes an excellent point.The rotating radar beams from most airport control towers is pretty powerful at short range.There have been strange RFI problems in airport neighborhoods which were traced to the radar systems.While the radar used for tracking in-flight craft in the general airspace likely have their beams tilted up to avoid ground interference,the systems that track ground-traffic (planes on the taxiways, etc.) probably have excellent signal strength right down onto the ground.There is surely no cell phone made that is immune from a direct radar beam at close range.

author: Unknown
author_rank: Unknown
timestamp: February 05, 2015, 10:41:39 am
content: Quote from: mojo-chan on February 05, 2015, 10:30:32 amAirport operators don't make that decision, certainly not in Australia. Even merepossessionof jamming devices is unlawful here, whether they are operating or not. To have parts of a cellular network shutdown is just a matter of a phone call or a radio message by the appropriate authorities. That order is then actioned by the carriers.In addition, prior knowledge of an attack is usually communicated to Policing agencies before it is to the airports, not the other way around. You'll find most airport employees aren't security cleared and aren't privy to that sort of information. If an immediate response to a threat is required, that's what your federal Policing agencies and Marshalls are for (in that case, see paragraph 1).

author: zapta
author_rank: Super Contributor
timestamp: February 05, 2015, 02:49:13 pm
content: Quote from: Richard Crowley on February 04, 2015, 05:44:10 pmOne explanation I heard was that cell phones on planes have line of sight to too many cells which creates disproportional load on the cellular system.

author: LabSpokane
author_rank: Super Contributor
timestamp: February 05, 2015, 04:30:18 pm
content: Quote from: zapta on February 05, 2015, 02:49:13 pmThe "technological barrier" is that cell towers intentionally do not broadcast their signal upward. Those antennas typically have physical or electrical downtilt built in in order to maximize the signal on the earth. Try flying with your phone on sometime. There is only a signal within a couple thousand feet AGL. At 35,000 feet there is bupkus.

author: SeanB
author_rank: Super Contributor
timestamp: February 05, 2015, 05:30:34 pm
content: The cellular antenna farm on the roof above me has a very flat beam, around 60 degrees either side of the vertical centre, and around 15 degrees off on the horizontal centre, with beam forming such that all the power is directed down. Level with the antenna the power is full level, but above it is almost zero, about 40dB down IIRC from the plate. As most users are found looking down from the high point and you want to have a well defined cell boundary this means very little power goes up. Directly under the antenna farm you actually have poor reception, and low signal strength. They do however ask us to contact them and ask them to reduce transmit power by 10dB when you go on the roof. they also added some railings to block off you being able to accidentally walk into the radiating portions of the antenna.

author: LabSpokane
author_rank: Super Contributor
timestamp: February 05, 2015, 05:49:30 pm
content: This is a very typical cellular antenna pattern. This particular model has 6 deg of electrical downtilt. There are side lobes that transmit to the sky, but the whole point of a cellular base station antenna is to direct its power toward its user base, which is terrestrial.Red = ElevationBlue and Green = Azimuth

author: vk6zgo
author_rank: Super Contributor
timestamp: February 07, 2015, 03:08:29 am
content: Apart from everything else,a "jammer"inside an aircraft would have to be FAA accredited.Anything in an aircraft needs to be flight rated,& the information on such certification would be available to the public.

author: Undweeber
author_rank: Regular Contributor
timestamp: March 11, 2015, 01:33:18 am
content: Quote from: Richard Crowley on February 04, 2015, 06:48:38 pmi think this makes the most sense, plus i was in economy plus closer to the front

author: richms
author_rank: Contributor
timestamp: March 11, 2015, 05:56:13 am
content: The inflight cellular gear has a weak jamming signal on all the unused bands to stop phones being used in flight from seeing weak signals from the ground network and trying to transmit back at full power.Its not supposed to be switched on untill they are over a certain altitude, and it is very weak so I doubt they would have any effect when you are on the ground in full coverage of a cell tower if it was inadvertantly left on.Onboard calling was only available for a short time here in NZ, noone used it as the pricing was so high, so few planes had it (only a couple) and people had it so drilled into them to not use phones on a plane that they were scared to try it even. Not sure if the gear is still on the planes that supported it or not.

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 06:00:42 am
content: Quote from: richms on March 11, 2015, 05:56:13 amNo, they don't. I'm a little concerned that you're getting your "facts" from a fortune cookie or something.

author: richms
author_rank: Contributor
timestamp: March 11, 2015, 06:18:31 am
content: https://gazette.govt.nz/notice/id/2011-go2763The table below sets out the frequency bands and power output limits for the operation of a radio transmitter, known as a Network Control Unit, used for the purpose of raising the radio spectrum noise floor inside an aircraft. The radio transmitter may only be operated when the aircraft is at an altitude greater than 3000 metres above ground.The following applies:Frequency Range (MHz) Maximum Power (eirp)870 - 885 -52 dBW935 - 9601805 - 18202110 - 2170

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 06:23:34 am
content: Yes, and that regulation only applies in New Zealand, no where else in the world. For example, the operation or possession of a jammer in Australia is unlawful. In order for an airline to operate a jammer, that device would have to be legal in every country that airline flies to.For example, the legislation here classifies a jammer as:a. the device is designed to have an adverse effect on radiocommunications; or would be likely substantially to interfere with, disrupt or disturb radiocommunications; andb. the device operates within one or more frequency bands used for the supply of a public mobile telecommunications service (whether or not the device also operates within other frequency bands).The only exceptions I'm aware of are for the Department of Corrective Services, Police and similar agencies.There is a clause which allows a device to operate on mobile phone bands on-board an aircraft only if that device facilitates carriage services (i.e.: a Picocell). It's cannot be used to deny service to a base station. The use of a jammer in-flight is next to useless as the handsets on-board will favour and register to the picocell above the ground stations due to the signal strength.

author: richms
author_rank: Contributor
timestamp: March 11, 2015, 06:28:08 am
content: Well its a good thing they dont operate them in Australia in that case.I know when there was testing there was a huge concern that the jamming power was high enough, as unlike the USA where using a mobile on a light aircraft is a problem legally, over here is is done extensivly so there is a lot of signal up in the air to make it work.On commercial flights up/down the country its common to get 2 bars of functioning LTE for long portions of the flight at cruising altitude.

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 06:30:36 am
content: As far as I know, no where in the world is it actually illegal to use a mobile phone on-board a commercial aircraft. However to disobey areasonable directionof flight crew is.

author: richms
author_rank: Contributor
timestamp: March 11, 2015, 06:42:27 am
content: Quote from: Halon on March 11, 2015, 06:30:36 amFCC in the US prohibit it. Rational dating back to analog/tdma interference concern days.

author: Unknown
author_rank: Unknown
timestamp: March 11, 2015, 09:20:41 am
content: Quote from: wilfred on March 11, 2015, 06:36:08 amJammers (Mobile, Radar, GPS or otherwise) have no place in the general population.