Thursday, December 13, 2012

iPad GPS

We get a lot of questions at GeoSpatial Experts about iPad GPS quality and generally how the GPS works in an iPad. 

If you are looking to buy an iPad and you are concerned about GPS, you need to purchase one with the 3G/cellular option.  The iPad with the 3G/cellular option has an embedded GPS. The WiFi only iPads do not have an embedded GPS.

Because the 3G iPad has a GPS chip, you can be in a completely disconnected environment (no internet, no WiFi) and still obtain GPS coordinates.  These iPad that have chips have AGPS chips so they generally have better start up performance or time-to-first-fix than some other GPS chips.  The newest cellular iPads also have GLONASS which allows you to access additional satellites.

How accurate is an iPad GPS?  To obtain GPS data, your iPad will first try to use the GPS chip, then WiFi, then cell tower triangulation.  Obviously the way it obtains a fix will affect the accuracy but there are some general guidelines for accuracy. 

When you use an iPhone or iPad to geotag a photo, the accuracy is about 100 feet (about 30 meters), because Apple only stores GPS data down to the nearest second in latitude and longitude. With our GeoJot+ app we actually store the full resolution of the GPS, which is the accuracy of a consumer GPS of 3-5 meters. You can see the accuracy on the screen and set accuracy requirements. 

We get similar questions for the iPhone but those are easier to answer.  All iPhones have a GPS chip.  All iPhones and iPads have a digital compass.

The information above is for iPad2s and newer.  We don’t even look at the original iPads because they don’t have cameras.

The iPod Touch does not have a GPS embedded.  Bad Elf can be a good GPS option For WiFi only iPads and the iPod Touch.  We have tested the Bad Elf GPS receivers with an iPod Touch and they have worked well.  They come in connected and Bluetooth models.

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