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I'd just like to ask for some clarifications regarding the GPS functionalities of android phones. When an application activates the GPS of a phone, will the phone need to be on a data plan or should activate the data traffic ( Settings > Wireless & Network settings > Mobile Networks > Data Traffic) for the GPS to get the phone's coordinates?

louieansonng
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From Wikipdeia

The Global Positioning System (GPS) is a space-based satellite navigation system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites. It is maintained by the United States government and is freely accessible to anyone with a GPS receiver.

If you talk specifically about GPS then it's nothing to do with the data plan or even with your service provider. GPS is totally independent of it. Think of a stand alone GPS receiver device e.g. Garmin GPS 10. It just connects to your laptop through Bluetooth (some with USB cable) and start sending GPS data to it. These devices normally output GPS data in NMEA format. Modern phones includes same sort GPS receiver circuit integrated in them. The thing different here is that these phones consumes GPS data for internally available rather than directly outputting in raw form. That's how you get GPS location information in iPhone and Android smart phones. On the other hand think of GPS navigation devices we use in our cars e.g. Garmin nuvi. It shows the location of car on the integrated maps. There is no sim card in it. Same is with GPS fitness watches.

A good question here is How GPS calculates the location? Best explanation I found is on HowStuffWorks. It's very easy and very well explained. Apart form GPS there are other positioning systems in the world, though GPS is oldest and most widely used. After GPS from US, there is GLONASS from Russia. Some phones support GLONASS too e.g. iPhone 4S and Samsung Galaxy S III. Well there is nothing to worry for developers though. These phones internally use GPS and GLONASS to have high positional accuracy and gives the location in same way.

Other positioning systems includes Compass from China and Galileo. These are under development at the moment. For complete list check this Wikipedia article.

Edit: Location can be also be determined by mobile networks and wifi networks. For example Google Latitude tells your approximate location if you are connected with wifi and even you don't have GPS device connected. In case of location determination by mobile networks, the service provider may charge for location. Normally locations determined by mobile and wifi networks are not very accurate but location can be determined indoors which is a very big problem of GPS location calculation.

Hopefully it will help how things are working.

Cheers! :)

ABH
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Atleast in India I can access use the GPS whenever I can see the sky, no data plan is required for me.

varuaa
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I haven't tried it on Android but it should be possible to get GPS co-ordinates without a data plan. My iPhone gets GPS locations even when out of reception, I can't see why android would be any different.

skorulis
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  • Yes... but acquiring a GPS fix "cold" can take a while, so when possible it will start with a "hint" obtained from the mobile network towers to speed the "search" for a geographic position that's consistent with the signals it is receiving from all of the GPS satellites it can see. – Chris Stratton May 20 '11 at 07:15