High Altitude Mobile Phone Reception
Thread Starter
High Altitude Mobile Phone Reception
I know this is not a Computer/Internet question, but I thought this was probably the best place to ask it.
I've just landed in Hong Kong after a flight from Los Angeles, which flew over Kamchatka and Korea enroute.
I had dutifully turned off my mobile phone but I had forgotten to turn off my second phone and I was surprised to see when I looked at it, that I had a "welcome" SMS message from a Russian phone carrier and that my phone had set itself to the Seoul time-zone.
Is it normal to be able to connect in this way from such high altitudes?
I've just landed in Hong Kong after a flight from Los Angeles, which flew over Kamchatka and Korea enroute.
I had dutifully turned off my mobile phone but I had forgotten to turn off my second phone and I was surprised to see when I looked at it, that I had a "welcome" SMS message from a Russian phone carrier and that my phone had set itself to the Seoul time-zone.
Is it normal to be able to connect in this way from such high altitudes?
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It IS normal that you can connect. Part of the reason for turning mobiles off for the trip is the sheer number of cell sites your phone can potentially register to during the trip (it causes problems for the providers).
Thread Starter
M-B,
I think it is NOT normal to connect, which is why I posted the question. I have left my phone on occasionally before and have never seen this behaviour.
Looking at the antenna lobe patterns for cell phone towers, with the primary lobe being horizontal, it really surprises me that any connection was made. I have tried in the past to use a cell/mobile phone from low altitude in a lightplane, with very poor results.
I think it is NOT normal to connect, which is why I posted the question. I have left my phone on occasionally before and have never seen this behaviour.
Looking at the antenna lobe patterns for cell phone towers, with the primary lobe being horizontal, it really surprises me that any connection was made. I have tried in the past to use a cell/mobile phone from low altitude in a lightplane, with very poor results.
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India Four Two,
Multipath propagation perhaps ?
Afterall, text messages etc. don't need much of a signal for long to work.
There is a brief discussion of it in a mobile specific context in the Nokia GSM Air Interface & Network Planning Training Document I just happened to stumble accross !
Multipath propagation perhaps ?
Afterall, text messages etc. don't need much of a signal for long to work.
There is a brief discussion of it in a mobile specific context in the Nokia GSM Air Interface & Network Planning Training Document I just happened to stumble accross !
Last edited by mixture; 3rd Apr 2012 at 08:18.
Looking at the antenna lobe patterns for cell phone towers, with the primary lobe being horizontal, it really surprises me that any connection was made. I have tried in the past to use a cell/mobile phone from low altitude in a lightplane, with very poor results.
Nowdays I'm in the 3G system, but I haven't had the chance or the need to see what happens there in the air. I suppose I should sometime, just in case it's important one day.
Thread Starter
Afterall, text messages etc. don't need much of a signal for long to work.
Doing a bit of Googling, I stumbled upon these two interesting papers that are pertinent to this subject:
Airborne Cell Phone Performance
Electromagnetic interference with aircraft systems
I suppose I should sometime, just in case it's important one day.
Based on my experience in Canada and New Zealand, there is an expectation by ATC that pilots will use mobile phones in the event of comms failure. I wonder how well that works in practice?
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FullOppositeRudder,
A couple of snippets from a previous thread on the subject.....
I wonder how well that works in practice?
Even used it to call ops before now while sat in the hold. My experience has been that over a certain speed the network just can't catch up!
The F.O. managed to get an SMS away at 35,000' when his mobile phone briefly picked up a signal. It wasn't a reliable signal though.
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Based on my experience in Canada and New Zealand, there is an expectation by ATC that pilots will use mobile phones in the event of comms failure. I wonder how well that works in practice?
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On the odd occasion that I've accidentally left mine on, and discovered it at cruise altitude, it has never had a signal. I think it disappears around 15 to 20 thousand feet.
In the R/T failure scenario, I assume it would be used at lower levels to talk to approach controllers, or the D&D cell (in UK).
In the R/T failure scenario, I assume it would be used at lower levels to talk to approach controllers, or the D&D cell (in UK).
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I think it disappears around 15 to 20 thousand feet.
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As has been mentioned earlier in the thread, t is possible to get the occasional multipath reflection. However, the antennae on cellphone masts are designed for horizontal propagation, and are very inefficient indeed at communicating with high-flying aircraft.
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Side lobe cell comms.
If you happen to pass through one of a cell site's side lobes you could communicate until you punched out of it. If you happened to know the location of the ground site, and you did some pre-flight planning you could orbit the ground site (inside that side lobe) and communicate until you ran out of fuel. Might not want to do this over the US of A.
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Text messages received
My other Pilot has Blackberry, and is always ON.
He receives most of his E Mails in flight this way.
Our DEP message is always on his BB before we land.
So there is some benefit.
Glf
He receives most of his E Mails in flight this way.
Our DEP message is always on his BB before we land.
So there is some benefit.
Glf
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Is newer better?
Slight thread drift.
I'm not really sure that newer is better.
Reference digital TV: When there is tropical storm activity in the local area two of the major networks become very intermittent with pixelisation of the video signal and clicking sound effects. It nearly blows my (expensive) surround sound system speakers apart.
Reference mobile phone reception: I used to regularly cancel SAR via mobile phone at 1500 ft in a very remote location in CDMA days. FA chance of doing that now with 3G.
Back to the original thread, sometimes whilst flying in remote areas my phone will report a service provider of 999 999 instead of Telstra in the service provider field. Does anyone know what this means? Free calls maybe??
I'm not really sure that newer is better.
Reference digital TV: When there is tropical storm activity in the local area two of the major networks become very intermittent with pixelisation of the video signal and clicking sound effects. It nearly blows my (expensive) surround sound system speakers apart.
Reference mobile phone reception: I used to regularly cancel SAR via mobile phone at 1500 ft in a very remote location in CDMA days. FA chance of doing that now with 3G.
Back to the original thread, sometimes whilst flying in remote areas my phone will report a service provider of 999 999 instead of Telstra in the service provider field. Does anyone know what this means? Free calls maybe??
Last edited by Two_dogs; 5th Aug 2012 at 13:34.
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There are some technical effects, too. I'm sure Googoo will reveal much more than I know.
In the UK, cellphone aerials are set to work horizontally and below. If there's reflection from something on the ground, then the signal may go up as well. The problem when the aerials worked with aircraft at altitude was that the airborne phone would access multiple towers and confuse the system. Some countries have a setup whereby a small number of towers have an upward-pointing aerial for aircraft - I think the USA is one such.
Straight GSM works on time-division multiplex, which sets an effective distance limit of about 20km, after which your returning signal is outside your timeslot. Although you may have a signal indication, you can't actually use it. Some rural sites have longer time slots, which increase the maximum range.
In the UK, cellphone aerials are set to work horizontally and below. If there's reflection from something on the ground, then the signal may go up as well. The problem when the aerials worked with aircraft at altitude was that the airborne phone would access multiple towers and confuse the system. Some countries have a setup whereby a small number of towers have an upward-pointing aerial for aircraft - I think the USA is one such.
Straight GSM works on time-division multiplex, which sets an effective distance limit of about 20km, after which your returning signal is outside your timeslot. Although you may have a signal indication, you can't actually use it. Some rural sites have longer time slots, which increase the maximum range.
