GPS

[scifan57]

Thanks. What is actually meant by assisted GPS and Glonass.. I know that GLONASS is the Russian version of GPS but what is the "assisted" bit mean.

Assisted GPS uses the cellular network help find your location quicker than GPS on its own. It's not any more accurate than unassisted GPS, it just gets a fix in less time. It also has access to features like real time traffic updates that are not available with unassisted GPS.

 

[twerppoet]

Assisted GPS (AGPS) is good old fashioned GPS with some extra stuff that makes it faster, and a bit more accurate. There are several of these extra technologies, and any Assited GPS may use one or more of them.

In the case of iOS devices it means that the iPad will use triangulation from nearby cellular towers and wi-fi hotspots for a quick, rought location estimate.

It also uses an internet or cellular connection to download the time tables and correction data necessary for GPS to work. Plain old GPS has to download these from the satelite transmissions, which can take a few minutes. Downloading them from the internet takes fractions of a second.

There may be some other things going on, but those are the two main assisting technologies.

The upshot is that on an iPad with no internet or cellular connection the GPS may take longer to find you're initial location, and depending on how many satelites are visible it may be slightly less accurate, but it will work.

In other words, it work about as well as a dedicated GPS unit under the same limitations. It possible the dedicated GPS unit will have a better antenna and radio, see more satelites, and therefore be a bit more accurate; but that would be a 'good' and probably moderately expensive GPS unit.

If you want more details of what AGPS is about, Wikipdedia has a pretty good article on the subject.

 

[Landcruiser262]

Assisted GPS (AGPS) is good old fashioned GPS with some extra stuff that makes it faster, and a bit more accurate. There are several of these extra technologies, and any Assited GPS may use one or more of them.

In the case of iOS devices it means that the iPad will use triangulation from nearby cellular towers and wi-fi hotspots for a quick, rought location estimate.

It also uses an internet or cellular connection to download the time tables and correction data necessary for GPS to work. Plain old GPS has to download these from the satelite transmissions, which can take a few minutes. Downloading them from the internet takes fractions of a second.

There may be some other things going on, but those are the two main assisting technologies.

The upshot is that on an iPad with no internet or cellular connection the GPS may take longer to find you're initial location, and depending on how many satelites are visible it may be slightly less accurate, but it will work.

In other words, it work about as well as a dedicated GPS unit under the same limitations. It possible the dedicated GPS unit will have a better antenna and radio, see more satelites, and therefore be a bit more accurate; but that would be a 'good' and probably moderately expensive GPS unit.

If you want more details of what AGPS is about, Wikipdedia has a pretty good article on the subject.

Thank you for all the information. I assume that there is some form of charge for the use of the cellular system via the Sim card. Am I limited to an Apple sim or can I use any pre loaded sim card from other companies? I am not that interested in any form of contract. A pay as you use would suit me.

 

[twerppoet]

Well, to use the cellular system at all, you need a SIM card. Pretty much any major cellphone carrier should do. Whether you need to have a cellular plan to use the assistive technologies for GPS, I don't know.

I suspect that the cellphone triangulation will work without a plan. Whether the GPS download data will work, no idea.

I think it's been mentioned before, but you should also keep in mind that most of the popular map apps for the iPad won't work without an internet connection, or be very limited. That includes Apple's own Maps app and Google Maps. But there are app that load local maps.