Anyone tried iPhone GPS aloft?
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Anyone tried iPhone GPS aloft?
I've just been trying to record the paths of my circuits with an app on my iPhone... the results have been pretty abysmal (not my circuits mind you, just the data recorded by the iPhone).
It's odd because on the ground it seems to work fairly well, but in the air it's as though it just keeps loosing the plot, and makes my circuits looks like a drunk spider has walked through an inkwell and staggered over the map.
One day I'll buy a proper GPS (I wouldn't dream of using the iPhone for any kind of navaid), but just wondered if anyone else had any success using iPhone GPS aloft?
It's odd because on the ground it seems to work fairly well, but in the air it's as though it just keeps loosing the plot, and makes my circuits looks like a drunk spider has walked through an inkwell and staggered over the map.
One day I'll buy a proper GPS (I wouldn't dream of using the iPhone for any kind of navaid), but just wondered if anyone else had any success using iPhone GPS aloft?
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I wouldn't dream of using the iPhone for any kind of navaid
I'd use anything in my arsenal as a navaid depending on circumstances.
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It's odd because on the ground it seems to work fairly well, but in the air it's as though it just keeps loosing the plot, and makes my circuits looks like a drunk spider has walked through an inkwell and staggered over the map.
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MIght have done some experimenting and found.... GPS worked well enough though the batt drain is very quick. Getting google maps to load the data quick enough to see where I was was tricky though 
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Main thing with the iPhone is that when you engage flight mode it switches the GPS off, despite the fact that it doesn't transmit in any way, shape or form. However I've found that it is much less prone to pipping in your ear, unlike the Nokia, if you leave flight mode switched off. Works just fine in the air providing it's reasonably near having a clear view of the sky. The new TomTom iPhone mount is perfect for affixing it to the screen.
There is 1 app in the app store which is any use, called QCTviewer, which will allow you to view the CAA VFR charts as produced by Memory Map, although it doesn't do much more than that at present; no GPX tracing or anything.
If you jailbreak your phone (lots of pros, no cons, but RTFM first) and know how to convert the QCT charts to a vendor-agnostic format you can take your pick as regards software. xGPS can happily utilise them and will record your routes for later scrutiny.
Now you can truly be free from the shackles of the world's worst operating system; the steaming turd that is Windoze Murbile.
There is 1 app in the app store which is any use, called QCTviewer, which will allow you to view the CAA VFR charts as produced by Memory Map, although it doesn't do much more than that at present; no GPX tracing or anything.
If you jailbreak your phone (lots of pros, no cons, but RTFM first) and know how to convert the QCT charts to a vendor-agnostic format you can take your pick as regards software. xGPS can happily utilise them and will record your routes for later scrutiny.
Now you can truly be free from the shackles of the world's worst operating system; the steaming turd that is Windoze Murbile.
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Not used the iphone but Ive found the Nokia N95 to be pretty accurate in the air both with position and speeds.
I switch it to flight mode to avoid any transmissions but run GPSed and UTM data apps and it records my flights very accurately.
Unfortunately there are no aviation chart apps for it that I know of.
Training Flight from Sherburn in Elmet | Track Log | GPS Track Log Viewer | goFLYING
I switch it to flight mode to avoid any transmissions but run GPSed and UTM data apps and it records my flights very accurately.
Unfortunately there are no aviation chart apps for it that I know of.
Training Flight from Sherburn in Elmet | Track Log | GPS Track Log Viewer | goFLYING
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hmmm interesting responses. Thanks. I've never jailbroke my phone - not really had time to look into it, and never really felt the need yet as I've managed to do what I needed without it. I used an app called Trails to track journeys but I've found the results are just crap - whether this is the app, mr the fact the Iphone was in my pocket while flying, I'm not sure. The door pocket on the microlight I fly is busted at the moment, so I couldn't pop it in there. I'll see if I can sort out a better mount, and try again.
Shunter was that screengrab from xGPS? If so, what did you use to convert the QCT charts to "vendor agnostic" formats (I presume that's a nerdy way of saying convert them to an open bitmap standard?)
Shunter was that screengrab from xGPS? If so, what did you use to convert the QCT charts to "vendor agnostic" formats (I presume that's a nerdy way of saying convert them to an open bitmap standard?)
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No need to jailbrake your iphone, there is skycharts ? Don't know if it works in europe
YouTube - SkyCharts
And then you have I-hud
i-HUD a mobile glass cockpit visualizer for the iPhone and iPod touch - iHUD app suite
YouTube - SkyCharts
And then you have I-hud
i-HUD a mobile glass cockpit visualizer for the iPhone and iPod touch - iHUD app suite
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It's odd because on the ground it seems to work fairly well, but in the air it's as though it just keeps loosing the plot, and makes my circuits looks like a drunk spider has walked through an inkwell and staggered over the map.
Haven't tried it in the air though. Isn't the iPhone 3GS supposed to have a better GPS (and a compass)?
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I think the new 3gs does have a proper compass, yes. GPS derived speed, and heading is maybe usable as a last resort backup on the iphone... but using any kind of AI derived from the iPhone's internal G sensors must surely be as much use as an ashtray on a motorbike?
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I always thought my N95 was pretty accurate, used it to track training rides on the bike, then one day I downloaded one of my tracks onto the PC, and found I'd been riding parallel to the shore, about 1 mile out to sea. 
As for the iphone, I'd love to know how the AH works 'cos if you're making a properly co-ordinated turn, it's sure not coming from the G sensors.. and I didn't think there were any gyros in there!
As for the iphone, I'd love to know how the AH works 'cos if you're making a properly co-ordinated turn, it's sure not coming from the G sensors.. and I didn't think there were any gyros in there!
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The GPS on my HTC phone works very well as an in-flight aid.
I wrote an artificial horizon app for it a while ago, which was fun but of course ultimately useless since it depended on input from the in-built accelerometer which is (necessarily) greatly influenced by acceleration. We should let Nokia/HTC/the others know about the demand for gyros in phones...
I wrote an artificial horizon app for it a while ago, which was fun but of course ultimately useless since it depended on input from the in-built accelerometer which is (necessarily) greatly influenced by acceleration. We should let Nokia/HTC/the others know about the demand for gyros in phones...
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Just thought i'd chime in with some info for you guys. The problem with GPS tracking on the iPhone is that the phone must be left active, you can't put it in standby. In standby, after a certain period of time, the iPhone turns off wi-fi and the GPS chip in order to save battery. Then when it reconnects the logged trip is erratic. So, you either have to keep touching the screen to keep it from going into standby, make sure you have an app that prevents it OR jailbreak it and get a plugin called insomnia which prevents this from happening. Hope that helps, I haven't tried it in the air but I use an app when I run so I can see how far I've gone/time/speed etc and it works fine so don't see why it wouldn't work for other apps/in the air.
Part of the problem is that phone GPS receivers are small and not very powerful. To help them fix their position, they use AGPS (assisted GPS) which help locate and track by triangulating off the base transmitters they are receiving. If you switch the phone part off, or are out of range then the system becomes less reliable. I have noticed this on my N95 when sailing out of range of a signal.
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I have been trying to use my GPS on my phone to track some of my flights. I assume it would work without any issue. However on each occasion it would track fine on the ground, departure and then cut out untill the approach.
Confused I came across the quote below:
"The biggest headache for GPS systems is the time it takes for the signal to get from the satellite to your receiver. The 6 satellites you get signals from will all be at different distances from you and are rotating the earth at high speed. So the signals your GPS receiver gets will not automatically be time synchronized. Because of this problem, the military has limited civilian GPS units so they don't work if they are moving faster than 900 knots or above 60,000 feet in altitude. But most non-aviation GPS units will give error messages if you are moving faster than 90 miles per hour. Clearly, if you are standing still, a GPS will be a lot more accurate. "
This seems to make sense, as pretty soon after departure the speed would be around 90kts (104 mph).
Considering the reciever in phones are not brilliant, it would make sense that that it could have trouble.
Confused I came across the quote below:
"The biggest headache for GPS systems is the time it takes for the signal to get from the satellite to your receiver. The 6 satellites you get signals from will all be at different distances from you and are rotating the earth at high speed. So the signals your GPS receiver gets will not automatically be time synchronized. Because of this problem, the military has limited civilian GPS units so they don't work if they are moving faster than 900 knots or above 60,000 feet in altitude. But most non-aviation GPS units will give error messages if you are moving faster than 90 miles per hour. Clearly, if you are standing still, a GPS will be a lot more accurate. "
This seems to make sense, as pretty soon after departure the speed would be around 90kts (104 mph).
Considering the reciever in phones are not brilliant, it would make sense that that it could have trouble.
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But most non-aviation GPS units will give error messages if you are moving faster than 90 miles per hour. Clearly, if you are standing still, a GPS will be a lot more accurate. "
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There is a number of separate issues here.
I am no specialist but this is from vague recollection:
To get initial signal acquisition, the GPS has to receive a special data packet. This is sent every 30 secs. If the reception of this is messed with (e.g. driving along a load of tall trees) you never get a fix. This is why, generally, getting an initial fix can be hard or impossible while moving.
Another thing is that one can optimise the receiver design to get a fast initial fix, but the design compromise is that subsequent loss of lock is more likely under less than great conditions. This prevents many GPSs getting an initial fix in a moving aircraft.
I have done tests on many GPS receivers and some are totally crap, as a result of the two factors above. Generally, older receivers are poor but some new ones too e.g. the new Thuraya satphones must be switch on on the ground for a few mins; if switched on in a moving aircraft they might never get a fix (and thus cannot be used to make a call).
Some are very good e.g. my Garmin 496 gets a signal anywhere anytime - but I am using an external (dashboard) antenna.
Generally, GPSs built into consumer products are not good because of the interference from the processor. I have a Fuji LOOX N560 PDA whose GPS is basically crap.
Reports on the Iphone vary. Some find it very good while others say the opposite.
But with any receiver there can be a big difference in the initial acquisition, and subsequent tracking. Two very different properties.
The 60,000ft ceiling, and other limits supposedly to prevent use in DIY missiles, is supposedly there in consumer GPSs, but it is a firmware feature and I would bet that a typical Chinese developer is not going to bother implementing it.
I am no specialist but this is from vague recollection:
To get initial signal acquisition, the GPS has to receive a special data packet. This is sent every 30 secs. If the reception of this is messed with (e.g. driving along a load of tall trees) you never get a fix. This is why, generally, getting an initial fix can be hard or impossible while moving.
Another thing is that one can optimise the receiver design to get a fast initial fix, but the design compromise is that subsequent loss of lock is more likely under less than great conditions. This prevents many GPSs getting an initial fix in a moving aircraft.
I have done tests on many GPS receivers and some are totally crap, as a result of the two factors above. Generally, older receivers are poor but some new ones too e.g. the new Thuraya satphones must be switch on on the ground for a few mins; if switched on in a moving aircraft they might never get a fix (and thus cannot be used to make a call).
Some are very good e.g. my Garmin 496 gets a signal anywhere anytime - but I am using an external (dashboard) antenna.
Generally, GPSs built into consumer products are not good because of the interference from the processor. I have a Fuji LOOX N560 PDA whose GPS is basically crap.
Reports on the Iphone vary. Some find it very good while others say the opposite.
But with any receiver there can be a big difference in the initial acquisition, and subsequent tracking. Two very different properties.
The 60,000ft ceiling, and other limits supposedly to prevent use in DIY missiles, is supposedly there in consumer GPSs, but it is a firmware feature and I would bet that a typical Chinese developer is not going to bother implementing it.
Last edited by IO540; 19th Nov 2009 at 09:39.