MacGregorSailors.com

Look into the IPad 3 spec-sheet on the Apple site, you'll see that the WIFI only IPad 3 has no GPS and the 4G-IPad 3 has "Assisted GPS and GLONASS".
That's why I and others spend the money to get a blue tooth GPS receiver.

Obelix

MotionX GPS is a great app for $1.99
You can download and store maps for off-line use such as hiking. It also has a page that shows your GPS reception and signal strength, the only app I know of that will do this.
For sailing however, the Navionics chart plotting apps are outstanding.

All GPS enabled cel phones and tablets use "Assisted GPS" which means they use cel phone triangulation to help get the initial lock on the GPS satellites. This allows them to use a smaller cheaper GPS chip than the dedicated hand held GPS units like Garmin or Trimble. These dedicated units have more sensitive receivers and store almanac data that tells them which satellites are in view to speed up the acquisition process, but they cost more and use more power. Having A-GPS doesn't mean you need cel phone service to get a GPS position, it just may take a little longer to get a lock without cel coverage if the phone/ tablet is not sure where it is. When I travel overseas, it sometimes takes as long as 15 minutes to get a GPS position, but it always gets it. Once you have updated your position, subsequent lock-ons are very quick.
Glonass is the Russian equivalent to GPS. Most newer GPS receivers can use Glonass satellites as well as GPS satellites.

Just bought the New iPad3 in June. I wondered the same thing regarding GPS. The following is an excerpt from the Apple User Guide for iOS 5.1 (I just updated to version 6 released this week, but the hardware is the same!), seems pretty clear, but build specs can vary over time for a model.

Maps, directions, and location-based apps depend on data services. These data services are subject to change and may not be available in all areas, resulting in maps, directions, or location-based information that may be unavailable, inaccurate, or incomplete.

- Brian.

Gents,

You're presuming that Assisted GPS is not true GPS but some dumbed down version using cellular triangulation. No true. Assisted GPS is a function where cellular tower triangulation is used to decrease the time needed to establish a valid fix (with GPS satellites). As an example, if you have a GPS in your car, you'll notice that it may take several minutes to lock in a location... usually displayed as "searching for satellites". This is not the case with an "assisted GPS" product which will lock in a location very quickly.

I love Wikipedia because it boils things down so that Zoology majors like me can understand...

"Standalone GPS provides first position in approximately 30–40 seconds. A Standalone GPS system needs orbital information of the satellites to calculate the current position. The data rate of the satellite signal is only 50 bit/s, so downloading orbital information like ephemeris and almanac directly from satellites typically takes a long time, and if the satellite signals are lost during the acquisition of this information, it is discarded and the standalone system has to start from scratch. In AGPS, the Network Operator deploys an AGPS server. These AGPS servers download the orbital information from the satellite and store it in the database. An AGPS capable device can connect to these servers and download this information using Mobile Network radio bearers such as GSM, CDMA, WCDMA, LTE or even using other wireless radio bearers such as Wi-Fi. Usually the data rate of these bearers is high, hence downloading orbital information takes less time."

So when I fire up my Navionics map I have instant location information, even with cellular data off BTW. Now, it will take about a minute for Navionics to display a heading and speed over ground. That's because the app is using GPS data (not AGPS) to make the calculation.

Bob
S/V Syzygy

So Bob, you're stating that the iPad has standalone GPS then?

- Brian.

Well I'm traveling with someone with an IPAD 2 and 3 with the Navionics app, so this should be a good data set to take

Brian,
Yes, that is correct. The kicker is that GPS is not a feature offered in the WIFI only iPad models because the GPS capability is resident with the 3G/4G chipset. I believe that is the source of the confusion...

Catigale,
As you run your trials you should notice a significant increase in GPS Time to First Fix if you initiate the Navionics app where you have no cell/WIFI coverage compared to a location with cell coverage or WIFI (dockside). BTW, this experiment should work if you're using the iPad's resident map app as well.

Bob

Update ...with an Ipad 2, model A1396 (wifi+AT&T cellular) Navionics did not find a fix in 15 minutes with cell and wifi turned off. I was in PHL airport next to a window.

Turning on cell, it locked in 5 seconds.

More to come...

Neither model will lock in 30 minutes under open sky in upstate NY

If I turn cell on, they lock immediately. When I turn cell off, the navionics app remembers the position but it does not move with the pad...I confirmed this by walking about 500 meters. I take this as definite proof that the A-GPS is cell only.

Unless someone can show me a screen shot to the contrary, I'm going to close this investigation as

"The Ipad will not function as a standalone GPS without cell coverage."

I currently run a Windows 7 system on an older Dell laptop inside the cabin. Not the best setup, for sure, but I am intrigued by the eventual outcome of this thread.
What I haven't seen mentioned is a workable protective cover for this device, that would retain the functionality of the touch screen, while properly venting the heat buildup while at the same time being able to handle a potentially very wet environment in the cockpit.

Ross

Catigale,

I agree, but would add to your conclusion: "or the assistance of a blue-tooth GPS-receiver"

Obelix

Catigale wrote:"The Ipad will not function as a standalone GPS without cell coverage."

I might suggest there is another way to tell if there is a gps onbaord. - download an app that shows that satilite positions and signal strength .

this is a android app that does this
http://androgeoid.com/2010/10/two-gener ... ps-status/
surely "i" stuff has one like this as well. If it gives a read out of the signal strength of each SV (space vechical) then surely you have gps. Internet can be used to help GPS out, but downloading the gps orbits (called the ephimeris, and almanac).

It is not necessarily proof that by turning on the cell modem it gives a lock - because MAYBE the gps and cell phone are the electronics, and turning on one, turns the other on.

do these units work outside of cell range (if you are outside of cell range?)

Sorry Gents... I feel that I must keep you pointed in the right direction.

More data for you at this link...

https://discussions.apple.com/thread/16 ... 0&tstart=0

Bob

Interresting thread in 2008

Obelix

Yep. It's been a topic for some time... At the end of the day the answer remains the same. I think a lot of the confusion comes from folks using the map apps that require data services because the map data is downloaded real-time vice resident on the devices. Navionics data is resident, at least the map areas that have been pre-downloaded. GPS coverage is key and the iphone/iPad antenna is probably not the best (as far as antenna gain goes) considering it's conformal to the shape of the device chassis.

Bob