i Pad and gps

[vyv_cox]

+1 There seems to be a lot of confusion over this.

1) Only the 3G iPad models have GPS

2) You do not need any kind of data signal (wifi or 3G) for the GPS to function.

3) Wifi only iPads do not have GPS

However, it is not always a perfect world. In Greece, unless my iPad2 (3G and wifi) is switched on in a port or location where my position is recognised, it often happens that the gps never catches up with me. In some places, e.g. North of Evia last year, the instrument insisted that we were somewhere up a mountain, presumably where the 3G transmitter is sited. This year in the southern Cyclades we have often not had a position on the iPad for days at a time. It may be that all will be well when in UK, where presumably there are more transmitters to aid the initial position finding, but it does not follow that everywhere will be the same.

 

[RupertW]

However, it is not always a perfect world. In Greece, unless my iPad2 (3G and wifi) is switched on in a port or location where my position is recognised, it often happens that the gps never catches up with me. In some places, e.g. North of Evia last year, the instrument insisted that we were somewhere up a mountain, presumably where the 3G transmitter is sited. This year in the southern Cyclades we have often not had a position on the iPad for days at a time. It may be that all will be well when in UK, where presumably there are more transmitters to aid the initial position finding, but it does not follow that everywhere will be the same.

I'm really surprised by this - I've found the Ipad 2 GPS position fine throughout the Adriatic as far down as Corfu over the last couple of years , even each time I take it straight from London so it has to find position again. I never have cellular on after leaving the UK and rarely wifi, so it is getting the position from its own GPS alone.

 

[dnickj]

This one looks pretty handy: http://amzn.to/1pL9LgW

Just a word of warning not all bluetooth GPS pucks work with Ipad you have to get one that is APPLE approved

 

[mjcoon]

However, it is not always a perfect world. In Greece, unless my iPad2 (3G and wifi) is switched on in a port or location where my position is recognised, it often happens that the gps never catches up with me. In some places, e.g. North of Evia last year, the instrument insisted that we were somewhere up a mountain, presumably where the 3G transmitter is sited. This year in the southern Cyclades we have often not had a position on the iPad for days at a time. It may be that all will be well when in UK, where presumably there are more transmitters to aid the initial position finding, but it does not follow that everywhere will be the same.

I had understood that so long as a GPS has continuous reception from one satellite for several minutes it should eventually collect the same information that would otherwise be got in seconds as "assistance" from the web.

My 1979 (IIRC) ancient Garmin GPS-II+ (the screen of which no longer works) had no such assistance feature, but would ask for a hint as to what country you were in. This made cold start faster than if you would/could not give an answer!

Mike.

 

[Buck Turgidson]

I had understood that so long as a GPS has continuous reception from one satellite for several minutes it should eventually collect the same information that would otherwise be got in seconds as "assistance" from the web.

My 1979 (IIRC) ancient Garmin GPS-II+ (the screen of which no longer works) had no such assistance feature, but would ask for a hint as to what country you were in. This made cold start faster than if you would/could not give an answer!

Mike.

This is correct and is correct for the iPad.

I turned mine on 400nm out in the Atlantic and had a fix within 3 minutes.

I suggest the user turns off his 3g and tries again or puts the iPad where it has a clear view of the sky!

 

[elton]

I had understood that so long as a GPS has continuous reception from one satellite for several minutes it should eventually collect the same information that would otherwise be got in seconds as "assistance" from the web.

My 1979 (IIRC) ancient Garmin GPS-II+ (the screen of which no longer works) had no such assistance feature, but would ask for a hint as to what country you were in. This made cold start faster than if you would/could not give an answer!

Mike.

The GPS receiver requires line of sight "visibility" of four or more satellites to determine position.

 

[vyv_cox]

I suggest the user turns off his 3g and tries again or puts the iPad where it has a clear view of the sky!

This season I have barely used 3G due to some problem at the Vodafone end that was consuming all my Gb allowance at a rapid rate. When sailing the iPad lives in the cockpit. For the past two seasons my gps position has been extremely temperamental, whether 3G or wifi were switched on or not. As I wrote earlier, if we leave a port with the gps knowing our position it will track us, whether the iPad is on deck or below. If not it will often not find us in several hours.

 

[mjcoon]

The GPS receiver requires line of sight "visibility" of four or more satellites to determine position.

Yes, but that is in addition to having the data that tells it where those satellites are in the sky, which is what can take longer.

Mike.

 

[noelex]

If not it will often not find us in several hours.

Vyv I think you probably have a technical problem with your GPS. I have the same iPad in the same area and it has never behaved like you describe.

I have no cellular sim, or connection on my iPad. I do have wifi connected most of the time, but I have never had any problems when out of WIFi range.

There has been some suggestion that the iPad may struggle downloading the satellite almanac from the satellites themselves (like an ordinary GPS does) if out of WIFi and cellular range for long time (weeks?). This may provide an alternative explanation. I have never tested this. The longest I have been out of WIFi range has been a couple weeks and the GPS was still working fine.

 

[vyv_cox]

I have wondered if it has a fault. I am currently in Sandbar Bay on Kithnos. My position according to Navionics HD is 2.9 miles out to sea.

 

[Vara]

I have wondered if it has a fault. I am currently in Sandbar Bay on Kithnos. My position according to Navionics HD is 2.9 miles out to sea.

i think you have a fault, my IPad has fixed accurately pretty well world wide with and without SIM card or wifi.

Might be worth checking your actual position with something like GPS test to ensure it's not a cartographic or datum error.

 

[mjcoon]

I have wondered if it has a fault. I am currently in Sandbar Bay on Kithnos. My position according to Navionics HD is 2.9 miles out to sea.

Meaning compared only with their cartography and/or some independent measure such as paper chart, Google Earth or whatever...?

Mike.

 

[vyv_cox]

Meaning compared only with their cartography and/or some independent measure such as paper chart, Google Earth or whatever...?

Mike.

Nothing at all wrong with the cartography, which is almost always very accurate.

This morning on passage I have been testing extensively. IPad on the sliding hatch, clear sky above. With wifi enabled but cellular off the gps failed to find us after 15 minutes. I then turned cellular on and it found us immediately. Turning cellular off again makes no difference, it is now tracking us perfectly. We are now not that far from Athens so presumably the 3G is able to triangulate our position initially? But this situation has been quite similar for the past couple of years.

 

[Monique]

FWIW, I use an iPad Mini (1 year old) in aircraft and on the boat. My version never needs 3G to determine its position.

However, OCCASIONALLY, if the unit has been placed in the "sleep" mode, the iPad cannot determine its GPS position upon "reawakening". If after a few minutes it fails to give an accurate position, turn it off altogether, then repower it after about 15 seconds of relaxation.

It always finds its position immediately in the aircraft or on the boat. Don't ask why....

 

[Buck Turgidson]

Nothing at all wrong with the cartography, which is almost always very accurate.

This morning on passage I have been testing extensively. IPad on the sliding hatch, clear sky above. With wifi enabled but cellular off the gps failed to find us after 15 minutes. I then turned cellular on and it found us immediately. Turning cellular off again makes no difference, it is now tracking us perfectly. We are now not that far from Athens so presumably the 3G is able to triangulate our position initially? But this situation has been quite similar for the past couple of years.

Very odd!
Unfortunately the boffins at apple don't allow developers access to satellite name and signal strength so it's not possible to see how many satellites the internal chip has got. 3 satellites is enough to track position but 4 would "probably" be required for first fix.
Of course the tracking may not be GPS derived at all and could well be "coasting" using the internal gyros of the ipad.
One more check I would do if I were you, turn off the wifi, remove the sim and give it 15 minutes of clear sky to see if it can fix.

Can you remind me which generation iPad it is?

 

[vyv_cox]

I'll try your suggestion, although the same thing has happened in Greece for two successive seasons, with a winter in Uk on a different SIM.
It's an iPad 2.
Thanks

 

[nigelmercier]

...I then turned cellular on and it found us immediately. Turning cellular off again makes no difference, it is now tracking us perfectly. We are now not that far from Athens so presumably the 3G is able to triangulate our position initially? ...

Exactly that, it's called Assisted GPS. Without any other clues, the GPS doesn't know what satellites to look for, so will always use its last known position. Turning on a second location system allows it to lock-up much faster, but then this can be turned off again.

 

[Monique]

Exactly that, it's called Assisted GPS. Without any other clues, the GPS doesn't know what satellites to look for, so will always use its last known position. Turning on a second location system allows it to lock-up much faster, but then this can be turned off again.

It may also be a reason why turning off the iPad then repowering allows it to clear itself of LKP and reinitialise itself....

 

[Rivers & creeks]

It's not wi-fi it needs; it needs a 3G signal to get a position if it doesn't have true GPS capability.

Very inaccurate. No wifi, 3G or any other signal required. It has in built full function GPS. Some will say it doesn't and that means that they don't have a 3g iPad or they would know better.

 

[Border Terrier]

See App Store : Veera Solutions OY. "Marine instruments display"

This app covers Lat/Long. Speed. Direction.