Maps and Mobile

One of the big advantages of owning a smartphone is that not only do you have a mobile computer with you at all times, you also have a compass, map, and restaurant guide.

There is some variation in the hardware your phone has installed, but in general your phone can tell where you are by using the following:

■ GPS (global positioning satellites)

■ Cell phone towers

■ WPS (Wireless Positioning System)

There are 27 global positioning satellites orbiting the Earth. Your phone's GPS unit attempts to find the signal from at least three of them and triangulate your position. However, this requires your phone to have a chip that detects GPS signals and be in an area that can detect them. If you're indoors or around lots of tall buildings, your phone might not pick up a GPS signal.

Your location can also be estimated using relative positions to cell phone towers. This isn't as accurate as GPS because cell towers are positioned for better signal reception, not triangulation, so there are generally not three overlapping points for positioning.

The third method of locating your phone comes from Skyhook Wireless and uses a map of known public Wi-Fi spots. Google uses a similar technique. It's a method that works well in urban areas and indoors—precisely the places where GPS does poorly. Because it only requires a Wi-Fi signal, it even works on laptops, netbooks, and tablets.

If you combine all three methods, you end up with a phone that usually knows where it is.

You can enable and disable your phone's ability to trace your location by pressing the physical Menu button while on the Home screen, and then Settings > Location & Security. You can also install a Power Control widget (this comes standard on Nexus One) to easily turn your GPS on and off.

This chapter will discuss using Google Maps and other location-conscious apps on your phone for both business and pleasure. You'll learn how to use your phone for driving directions, deciding where to eat, and letting your friends know where to find you.

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