Apple's iPhone 4, released in June 2010, includes an assisted-GPS application that provides a variety of navigational features, including turn-by-turn directions and location-based services. These A-GPS features are produced by the iPhone's ability to use a combination of cellular tower, Wi-Fi and satellite signals to generate location data. The phone's GPS functionality interacts with several of its features to provide location-related features.
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The iPhone 4's A-GPS feature provides location-specific data that can be faster and more accurate than standalone GPS units and that can work in areas in which standalone models have difficulty, such as dense urban areas and indoors. AT&T and Verizon Wireless, the iPhone 4's wireless service providers, have location servers on their networks that tell the phone which satellites to connect to for navigational data. These location servers also perform the complex calculations needed to produce exact location data. This information is used by several of the iPhone 4's features, including location-based services (LBS) and the device's digital camera.
The iPhone 4's LBS feature works by interfacing with its A-GPS application to provide contact information for nearby commercial and emergency services, such as hospitals, police stations, gas stations and restaurants. The LBS feature also allows third parties, such as employers and parents, to track the location of the device through a personal computer. The LBS feature also produces turn-by-turn directions from point A to point B and gives you access to social networking services, including Twitter and Facebook. LBS technology provides precise location data without requiring you to enter your location into mapping applications such as Google Maps, by automatically coordinating satellite and cellular tower signals.
Equipped with a 5-megapixel camera that takes still pictures at up to 2,592 by 1,944 pixels of resolution and is capable of recording high-definition video at 720 pixels of vertical resolution, the iPhone 4 is capable of geotagging. The iPhone's geotagging feature works by interfacing with its A-GPS and LBS technology to embed map and GPS coordinate data into each picture and video taken by the phone. This feature is especially helpful if you want to return to the exact location of a previously taken photo or if you are unsure of your precise location.
Google Maps comes preinstalled on the iPhone 4 and is the application through which much of the phone's A-GPS and LBS data is reported. The Google Maps app provides many of the features offered by its online relative, including Street View and onscreen turn-by-turn directions. If you tire of all the fancy technology of today's GPS technology, the iPhone 4 also comes with a digital version of that tried-and-true navigational tool from yesteryear: the compass.