Regulation of mobile phones on GA flights
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How in all the world can you tell?
If accidental mobile phone activity at altitude was a technology/ asset/capacity utilisation issue for the networks, they have had ample time to assess the extent of it and do something about it - perhaps by software fixes which reduce the probability of such a phone getting a connection of any kind (which, looking at how relatively useless phones are even for sending text messages when airborne, wouldn't suprise me and that is exactly how I would have solved this - any phone seen to be connecting to multiple networks within say 1 second will be barred from all of them for say the next 100 seconds).
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jeling as I said previously it is comletely dependent on how the BSC is setup.
And I presume you know that differnet phone do GPS in different ways. For example the N95 needs a signal for it to work and N96 can do it in airplane mode. THe N96 was quite happy maintaining lock at FL200 and 250knts TAS. In fact it was alot happier there than wandering around london.
The time frame for how often the handset poles the BSC depends what make of handset it is. From memory Ericisson does it every 13mins and Nokia's every 45mins which is why nokia for years had a huge advantage over standby time compared to all the rest.
And I presume you know that differnet phone do GPS in different ways. For example the N95 needs a signal for it to work and N96 can do it in airplane mode. THe N96 was quite happy maintaining lock at FL200 and 250knts TAS. In fact it was alot happier there than wandering around london.
The time frame for how often the handset poles the BSC depends what make of handset it is. From memory Ericisson does it every 13mins and Nokia's every 45mins which is why nokia for years had a huge advantage over standby time compared to all the rest.
Thats wrong, the N95 works with no problems in offline mode.
I have a N95 8GB and regularly use it to track my flights when I am PIC with no problems and its just sat on the seat in the back. I can then upload the tracks to the goFLYING website or google earth etc.
They do have a feature of assisted GPS which uses cell sites to get a rough idea of your location (which even without GPS is usually within half a mile, but this is not obviously on when you are in offline mode). The main reason I keep mine in offline mode while I am flying PIC it is to avoid the interference on the headset. Not because my phone being on will cause the whole mobile network to collapse and satellites to fall from the sky!
In fact even on airliners it has no issues maintaining lock over 500mph, while in Offline mode. (Flight mode and no cell signal) Even OVI maps (nokia maps 3) can track my route real time. Interesting to have on since live mapping on screens on board is rare on flights these days especially the shorter flights.
To be honest I think most people would be surprised how well the GPS works on Nokia handsets especially the Nseries devices. They are getting even better too, the N86 8MP has a built in compass too which it uses to build a better picture of your navigation.
I only know of Jet2 that actually say they allow you to select flight or offline mode, while others dont. I honestly think that airlines need to re-think their policies. So long as you dont set up a 14metre HAM radio station while on board I cannot see phones causing issues in aircraft especially with offine mode selected. Wonder what the air steward would say to having this device swithed on:
BLACK-BOX Airband Monitor @ Flightstore Pilot Supplies
The use of phones in GA aircraft is not covered anywhere in the PPL syllabus. Note the term for SE phones "Flight Mode".
Screenshots to show phone had no issues maintaining GPS lock on an airline:- Last shot is on way back, with head wind
Last edited by liam548; 3rd Oct 2009 at 16:47.
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We are in advanced Beta testing of a mobile phone application. We want to determine what the level is that we can work with to get a phone signal. Not too concerned if we loose phone signal as we have ways of dealing with it.
Also keen to see how well the GPS's in the phones hold lock.
James
Also keen to see how well the GPS's in the phones hold lock.
James
James see my post above. Apologies if it has been posted but what is this application you are creating, I am interested in it. What platform will it be on?
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One thing you can never get around is that a phone that is visible from many cells uses up radio resources in all those cells.
The only similarity between a mobile phone & an aircraft transceiver is that they both use the radio spectrum - there is no other comparison!
In the mobile phone case the network (computers - heard of them) allocates resources and in modern networks allocates resources at a single cell site to individual phones. Yes the other cells can see the phone, but that is all.
As the signal strength at those sites varies the network will eventually transfer the individual phone to another site.
It is worth noting that:-
Adjacent cell sites use different frequencies
Phones are frequency agile & transmit/recieve on frequencies to match the site they are allocated to, the network tells the phone which frequency to use
If the phone can see another site using the same frequency, the network will still not allow traffic through mulitiple sites.
As regards use in aircraft, the instruction manual (in the safe use section) for the Nokia I just got states that use onboard an aircraft is illegal, of course you have all read your instrucion manuals!
Last edited by west lakes; 3rd Oct 2009 at 16:19.
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This keeps coming up time and time again and is incorrect (I'm fed up of posting tech details as to why)
The only similarity between a mobile phone & an aircraft transceiver is that they both use the radio spectrum - there is no other comparison!
In the mobile phone case the network (computers - heard of them) allocates resources and in modern networks allocates resources at a single cell site to individual phones. Yes the other cells can see the phone, but that is all.
As the signal strength at those sites varies the network will eventually transfer the individual phone to another site.
It is worth noting that:-
Adjacent cell sites use different frequencies
Phones are frequency agile & transmit/recieve on frequencies to match the site they are allocated to, the network tells the phone which frequency to use
If the phone can see another site using the same frequency, the network will still not allow traffic through mulitiple sites.
The only similarity between a mobile phone & an aircraft transceiver is that they both use the radio spectrum - there is no other comparison!
In the mobile phone case the network (computers - heard of them) allocates resources and in modern networks allocates resources at a single cell site to individual phones. Yes the other cells can see the phone, but that is all.
As the signal strength at those sites varies the network will eventually transfer the individual phone to another site.
It is worth noting that:-
Adjacent cell sites use different frequencies
Phones are frequency agile & transmit/recieve on frequencies to match the site they are allocated to, the network tells the phone which frequency to use
If the phone can see another site using the same frequency, the network will still not allow traffic through mulitiple sites.
But I am talking about something else entirely; even though the network will not go down and connectivity is not lost, capacity in each cell can go down. To see why, one really has to consider the radio side of the problem, not just the back-end and networking aspects. The key point is that the better the quality of the radio channel, the less radio resources are needed to achieve a given performance (bit rate, capacity, etc).
The radio channel is generally fading- and/or interference limited. Interference can loosely be said to manifest itself as 'noise'. Phones and base stations that have some degree of overlap between the radio resources they use will appear as noise sources to each other. For WCDMA there is always such overlap since all spreading codes are not quite orthogonal; for GSM there can be such overlap between phones in neighboring cells (more on that later). To the extent the channel is interference limited, adding more interference has to be offset by using up more radio resources.
As an example, somewhat still in the future, one can look at the constellation diagrams for 16-QAM vs. 64-QAM (should be on Wikipedia somewhere). Even intuitively one can surmise that 64-QAM will be more sensitive to the channel quality than 16-QAM, since the dots are more densely packed in the diagram. If one does the math one comes to the same conclusion. If the added interference would be enough to force the controller to switch from 64-QAM to 16-QAM for a particular link, instantaneous bit rate drops by roughly 33 %. Now the base station has to spend proportionally more time talking to a particular cell phone to provide the same data rate, or the user will see a drop in data rate. The same principle applies to the other radio resources that are required for a particular radio access technology.
You talk about how resources are allocated to individual phones. When doing the cell planning, which determines what resources the different cells have available to allocate to phones in thair area, one takes into account the distance that a particular phone will be 'loud' enough to interfere measurably with other phones and base stations. Radio resources are re-used in cells that are far enough apart for interference to be sufficiently low. But an airborne phone will be visible from far longer distances than was considered during cell planning, and will therefore cause much more interference than predicted.
If there are still free resources available, such as free frequencies in GSM, the cells can null out the interferer and keep functioning at full capacity. But a sensibly dimensioned network will be working near full capacity part of the time. If the operator wanted to save some money on the configurations it could be working near full capacity all the time, sharing the available capacity between the users. Any interference that reduces capacity in those cases will immediately reduce the bandwidth, quality etc for the user. For instance, in a GSM network running at high capacity there may not be any free frequencies available when an airborne phone is visible in many cells simultaneously. Some phones can therefore be forced to use the same frequency as the distant airborne phones, and use other means to deal with the interference created (increase their transmit power etc).
Again, none of this is likely to be a problem with the occasional airborne phone. The effects will hardly be measurable. But if cell phones were routinely used in the air, the factors I am talking about would definitely manifest themselves, make no mistake about that. The operators would have to build bigger radio base station configurations to achieve the same capacity, costing them money (and guess who would have to pay for that; not their share holders!). Or, perhaps more likely, the users would see their network performance drop. They might not even notice that drop, or realize why it happens, but they would get less performance than if the airborne phones were not there.
The mobile phone scene, and the jet transport scene, have been more or less constant for years.
We are delivering networks that are capable of over 40 Mbit/s already, with over 80 Mbit/s just around the corner, and that is still WCDMA. Over 20 Mbit/s is already in use. We are already delivering the first 100+ Mbit/s LTE networks (field trials up and running, individual sites up in the live nets). We didn't sell those things 10 years ago.
If accidental mobile phone activity at altitude was a technology/ asset/capacity utilisation issue for the networks, they have had ample time to assess the extent of it and do something about it - perhaps by software fixes which reduce the probability of such a phone getting a connection of any kind (which, looking at how relatively useless phones are even for sending text messages when airborne, wouldn't suprise me and that is exactly how I would have solved this - any phone seen to be connecting to multiple networks within say 1 second will be barred from all of them for say the next 100 seconds).
Last edited by bjornhall; 4th Oct 2009 at 13:04. Reason: clarifying a couple things and fixed a dumb error
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Hi Liam,
The application is GPS Logbooks - Home | Black Box Flight Recording, using only your Android cell phone. It is now working on Windows Mobile, iPhone and Android.
We have it now returning points every second and being updated on the website in realtime.
Feel free to download the application (it is free) and send through any feedback.
Cheers,
James
The application is GPS Logbooks - Home | Black Box Flight Recording, using only your Android cell phone. It is now working on Windows Mobile, iPhone and Android.
We have it now returning points every second and being updated on the website in realtime.
Feel free to download the application (it is free) and send through any feedback.
Cheers,
James
