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Ten ways your smartphone knows where you are

Location tools go well beyond GPS and Wi-Fi and increasingly can deliver high accuracy even indoors

By , IDG News Service
April 06, 2012 09:45 AM ET

IDG News Service - One of the most important capabilities that smartphones now have is knowing where they are. More than desktops, laptops, personal navigation devices or even tablets, which are harder to take with you, a smartphone can combine its location with many other pieces of data to make new services available.

"There's a gamification aspect, there's a social aspect, and there's a utilitarian aspect," said analyst Avi Greengart of Current Analysis. Greengart believes cellphone location is in its second stage, moving beyond basic mapping and directions to social and other applications. The third stage may bring uses we haven't even foreseen.

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Like other digital technologies, these new capabilities come with worries as well as benefits. Consumers are particularly concerned about privacy when it comes to location because knowing where you are has implications for physical safety from stalking or arrest, said Seth Schoen, senior staff technologist at the Electronic Frontier Foundation. Yet most people have embraced location-based services without thinking about dangers such as service providers handing over location data in lawsuits or hackers stealing it from app vendors.

"This transition has been so quick that people haven't exactly thought through the implications on a large scale," Schoen said. "Most people aren't even very clear on which location technologies are active and which are passive." Many app-provider practices are buried in long terms of service. Risk increases with the number of apps that you authorize to collect location data, according to Schoen, so consumers have at least one element of control.

There are at least 10 different systems in use or being developed that a phone could use to identify its location. In most cases, several are used in combination, with one stepping in where another becomes less effective.

1. GPS

Global Positioning System was developed by the U.S. Department of Defense and was first included in cellphones in the late 1990s. It's still the best-known way to find your location outdoors. GPS uses a constellation of satellites that send location and timing data from space directly to your phone. If the phone can pick up signals from three satellites, it can show where you are on a flat map, and with four, it can also show your elevation. Other governments have developed their own systems similar to GPS, but rather than conflicting with it, they can actually make outdoor location easier. Russia's GLONASS is already live and China's Compass is in trials. Europe's Galileo and Japan's Quasi-Zenith Satellite System are also on the way. Phone chip makers are developing processors that can use multiple satellite constellations to get a location fix faster.

2. Assisted GPS

GPS works well once your phone finds three or four satellites, but that may take a long time, or not happen at all if you're indoors or in an "urban canyon" of buildings that reflect satellite signals. Assisted GPS describes a collection of tools that help to solve that problem. One reason for the wait is that when it first finds the satellites, the phone needs to download information about where they will be for the next four hours. The phone needs that information to keep tracking the satellites. As soon as the information reaches the phone, full GPS service starts. Carriers can now send that data over a cellular or Wi-Fi network, which is a lot faster than a satellite link. This may cut GPS startup time from 45 seconds to 15 seconds or less, though it's still unpredictable, said Guylain Roy-MacHabee, CEO of location technology company RX Networks.

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