Which Model to Buy? iPad 2’s Assisted GPS Demystified

There seems to be quite a bit of confusion online about what exactly “Assisted GPS” on Apple’s iOS (s aapl) devices is, especially regarding navigation-based app requirements. It can be a bit complicated, but understanding what it means could help you decide which iPad to buy.

For developers, the Core Location Framework in iOS can use the onboard GPS, cell, or Wi-Fi radios to find the user’s current longitude and latitude. Each one has a different degree of accuracy and uses a different amount of battery life.  This abstraction allows developers to write code without exactly knowing what capabilities the iOS device has available to it.  So, for the most part, developers don’t always have strict requirements where GPS capabilities are concerned.  But as a consumer, you want to know exactly what you’re getting for your money.

Wi-Fi iPad 2 and iPod Touch’s Wi-Fi Database

According to the tech specs for the iPod touch, this iOS device has what is referred to as “Maps location-based service”.  This means that the user’s longitude and latitude are determined based on their proximity to known Wi-Fi networks.  Since iOS 3.2, Apple has claimed to be using its own databases to provide such location-based services.  So we know that the iPod touch and the Wi-Fi only iPad 2 aren’t using GPS, but what about the iPhone 4 and 3G-capable iPad 2?

Wi-Fi + 3G iPad 2 and iPhone 4’s Assisted GPS

With GPS devices, the assisted terminology refers to the fact that the resulting GPS data is enhanced.  Under certain conditions, this enhancement can speed the start-up time to get an initial location fix faster.  So the same technology that’s used in the iPod touch to determine a user’s location based on Wi-Fi proximity is being used on the iPhone and the Wi-Fi + 3G iPad 2 to assist these devices in getting that initial fix.  The tech specs for the iPad 2 claim that only the Wi-Fi + 3G model has this “Assisted GPS” feature, and this is the same feature found on the iPhone.  The Wi-Fi only model of the iPad 2 does not have this feature.

What Good is GPS on an iPad Beyond Online Maps?

While it is certainly true that the built-in Maps App is pretty much useless without data connectivity, there are an increasing number of apps that will either cache, install or download maps for offline access.  MotionX GPS HD for US $2.99 in the App Store has what is likely to be one of the better implementations of downloading maps at a very reasonable price.  GPS also means you’ll have more accurate results when using location-based recommendation or social networking apps. It’s not something that everyone needs, but as it becomes more and more popular, it could represent a significant upside to owning an iPad, so consider the benefits of assisted GPS when making your choice.