Ipad internal GPS reliability
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I have tried Skydemon on an iPad2 3G, using the internal GPS in a PA28, and it worked fine, had a fix immediately.
Maybe not all iPads are the same, but I don't need an external GPS.
Maybe not all iPads are the same, but I don't need an external GPS.
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There is no GPS (as we all know it) in an iPad or iPhone. They call it assisted gps and it is just autotriangulation from cellular network masts.
Get the proper (swipe) bluetooth gps, the GNS 5870 MFI, you'll love it.
I can't imagine going back to "just" the twin dash mounted GNS430s in the PA 28 I fly. Memory Map on the New iPad (it's not called the iPad3) is fantastic.
Get the proper (swipe) bluetooth gps, the GNS 5870 MFI, you'll love it.
I can't imagine going back to "just" the twin dash mounted GNS430s in the PA 28 I fly. Memory Map on the New iPad (it's not called the iPad3) is fantastic.
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An Iphone4 or an Ipad2/3G have a full GPS receiver.
It's not a particularly good one. It's compromised for low power consumption over capture performance. But it is a real GPS.
It's not a particularly good one. It's compromised for low power consumption over capture performance. But it is a real GPS.
There is no GPS (as we all know it) in an iPad or iPhone. They call it assisted gps and it is just autotriangulation from cellular network masts.
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The new iPad3 is much the same so far as the GPS is concerned as long as you select the with 3G model. I find it is pretty reliable but if I intended to depend on the iPad then I would probably buy one of the dedicated receivers that are available for the iPad.
For avaition use (but I have to say I rarely use mine for that purpose and it was not the reason I use an iPad) it is a reasonable, if not great piece of kit. Personally the dedicated receivers from the likes of Garmins have the edge in my opinion for readability in bright light and reliability but the size of the screen on the iPad is superb feature.
If I wanted a moving map GPS solely for flying I still wouldnt buy an iPad but its a close call.
For avaition use (but I have to say I rarely use mine for that purpose and it was not the reason I use an iPad) it is a reasonable, if not great piece of kit. Personally the dedicated receivers from the likes of Garmins have the edge in my opinion for readability in bright light and reliability but the size of the screen on the iPad is superb feature.
If I wanted a moving map GPS solely for flying I still wouldnt buy an iPad but its a close call.
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So, am I better off buying a WiFi and an external GPS receiver then? I nearly bought a 3G yesterday so that I could use SkyDemon on it on the internal GPS - the amount of people saying how well it worked nearly made me want to eat my own words about iDevice GPS reliability.
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I've used my iPad2 for almost 100hrs and on over 3000nm long cross country trips. I have had one "unable to find fix" in all this time and it lasted for less than 2 minutes. It consistently delivers 10m accuracy, often less than 5m. I did buy a BadElf external GPS that plugs in to the charging socket, but don't use it much as I can't charge through it (the charger provided blew up on 24V, of course).
The iPad2 and Foreflight here in the US has literally changed my life. It's the best thing ever.
The iPad2 and Foreflight here in the US has literally changed my life. It's the best thing ever.
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Assisted GPS (A-GPS) means that getting the initial GPS fix is sped up through use of downloaded data, rather than having to get the data directly from the satellites. It is still GPS - using the same satellites to get a position fix as all other GPS devices. Once an initial fix is established, downloaded data is not longer used.
When on the ground, you are likely to notice that getting an initial fix is much faster on devices (phones, etc) using this, especially in built up areas, than traditional GPS devices.
The issue is that some devices appear to rely heavily on A-GPS to get their initial fix. Therefore if you try to start such devices when there is no data network available, they can struggle to ever get a GPS fix (the long lag time may cause something to time out, and so will no longer look for a signal).
If no network data is available, satellite data needs downloaded from the satellites themselves, which requires maintaining a download from a single satellite for about 30-40 seconds. If a device has a poor receiver, or in a poor signal area, an initial fix will never seem to happen.
See Assisted GPS - Wikipedia, the free encyclopedia
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Indeed.
However if you switch apps, and so turn off searching for GPS - you will be back to the start of getting an initial fix again. The GPS receivers on multi-purpose devices aren't as sensitive as the specialist devices so it does depend on which plane you are flying in as to whether you can rely on the internal ones.
However if you switch apps, and so turn off searching for GPS - you will be back to the start of getting an initial fix again. The GPS receivers on multi-purpose devices aren't as sensitive as the specialist devices so it does depend on which plane you are flying in as to whether you can rely on the internal ones.
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So the best bet is to get it going on the ground to get a decent position fix and then it ought to be ok?
However if you switch apps, and so turn off searching for GPS - you will be back to the start of getting an initial fix again.
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I have just got the Dual GPS.
It works OK, and the free phone shop app shows the satellite details too.
But there is no way, in the Ipad2, to select which GPS to use. I have so far only tried it with Memory Map and it appears that if the external GPS dies, the app just quietly stops working, or quietly switches over to the built-in GPS - with its reliability issues.
I don't know if other GPS apps on IOS have an explicit config for which GPS to use, but I have never seen this. It's really crap.
The only solution is to put the Ipad into Airplane mode, when the internal GPS is disabled.
The other thing I noticed that when the GPS battery goes flat, the MM app just sits there, showing the last position. No message, no warning...
It works OK, and the free phone shop app shows the satellite details too.
But there is no way, in the Ipad2, to select which GPS to use. I have so far only tried it with Memory Map and it appears that if the external GPS dies, the app just quietly stops working, or quietly switches over to the built-in GPS - with its reliability issues.
I don't know if other GPS apps on IOS have an explicit config for which GPS to use, but I have never seen this. It's really crap.
The only solution is to put the Ipad into Airplane mode, when the internal GPS is disabled.
The other thing I noticed that when the GPS battery goes flat, the MM app just sits there, showing the last position. No message, no warning...
The other thing I noticed that when the GPS battery goes flat, the MM app just sits there, showing the last position. No message, no warning...
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It uses any external device in preference to the internal one.
There is an API provided by Dual which allows an application to see the full satellite constellation, DoP and battery charge level. It may be worth 'feeding back' to Memory Map that this would be a good idea.
MM really should alert on loss of GPS reception. It is far too subtle at the moment.
I have so far only tried it with Memory Map and it appears that if the external GPS dies, the app just quietly stops working, or quietly switches over to the built-in GPS - with its reliability issues.
The other thing I noticed that when the GPS battery goes flat, the MM app just sits there, showing the last position. No message, no warning...
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The Ipad2 uses a Broadcom 4751 integrated GPS chip. Which is excellent but limited with its aerial.
A better solution seems to be an external GPS receiver (can be bluetooth or USB), we find the latest Skytraq Venus 6 chipset models hard to beat in terms of speed and the ability to remain locked to sats.
A better solution seems to be an external GPS receiver (can be bluetooth or USB), we find the latest Skytraq Venus 6 chipset models hard to beat in terms of speed and the ability to remain locked to sats.
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It uses any external device in preference to the internal one.
I've found the bluetooth link to be very dependent on the GPS being well charged, versus the distance between the two units. So when the battery runs down (to a point which is dependent on the connection distance) there will be a point in time when the thing basically becomes unusable, but this point can't be determined readily, it appears. Then at some point the Ipad will try using its internal GPS, which I find highly flakey during flight. Whereas with the NMEA serial data used on all other portable devices the app can immediately tell if the data is rubbish - within about a second or two.
The inability to explicitly configure which GPS to use is really stupid.
It may be worth 'feeding back' to Memory Map that this would be a good idea.
TBH the moment Oziexplorer comes out for IOS, MM will be history. The only reason anybody in GA uses MM is because the CAA charts come in its format, but it doesn't take long for somebody out there to scan them in into a generic graphic file...
I do have the IOS app for the Dual GPS, which shows the sat data. It's slick. Oddly enough it won't compute a fix with less than about 8 "green" satellites though.
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Memory map is crap. Half the problems you are seeing with the GPS are down to it. I switched to ANP and gave never experienced any of the GPS problems you have. It allows use of the CAA charts and s way more useful.
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The ANP website doesn't appear to indicate one can load own maps onto it.
Re the bluetooth GPS connection... one thing I see is that if you switch apps on the Ipad, the connection is briefly broken. I don't think Apple meant this as a serious nav device.
Re the bluetooth GPS connection... one thing I see is that if you switch apps on the Ipad, the connection is briefly broken. I don't think Apple meant this as a serious nav device.
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I suspect Memory Map's issue is that the iOS APIs don't include a way of telling whether a location device is even connected, never mind controlling which device should be used. All they say is "location is X, with an accuracy of y". You then need to work out whether the accuracy is good enough (or the phone is actually using cell tower triangulation)...
Since their App was one of the first (if not thee first) on the market to use a GPS on iOS, it will have been written before the other libraries were available. For them to get more detailed GPS info, they will need to re-write that section of their code, but using other GPS libraries, which is probably not trivial. The libraries are specific to each GPS type, so may not work with future released external devices. From a developer's point of view, that will add an additional cost to manage and support the app.
I doubt its rocket science though - and to me it seems a must have feature!
Since their App was one of the first (if not thee first) on the market to use a GPS on iOS, it will have been written before the other libraries were available. For them to get more detailed GPS info, they will need to re-write that section of their code, but using other GPS libraries, which is probably not trivial. The libraries are specific to each GPS type, so may not work with future released external devices. From a developer's point of view, that will add an additional cost to manage and support the app.
I doubt its rocket science though - and to me it seems a must have feature!