Late-model smartphones come with large color screens, powerful processors, and built-in GPS circuitry for emergency location. This corresponds closely to the basic components of a standalone GPS navigation device, so it's not surprising that there are a number of GPS apps available for the leading smartphone operating systems. While they vary in their features and performance, they're broadly similar in how they work.
The GPS system was originally established by the U.S. military for its own use, and later became available to civilians around the world. Portable receivers work by locating low-power radio signals from the network of GPS satellites, and interpreting their position and movement data. Once a GPS device has located three to five satellites, it can calculate its position on the earth's surface by triangulating from the satellites. When the device can acquire signals from five satellites, it can even provide your elevation and usually your speed of travel.
GPS on Smartphones
The GPS chipset built into cell phones provides that same capability -- and smartphones have both the screen and processor power to calculate and display the data. The only extras they need are a source of maps and software to provide the GPS features. Many apps use NavTeq or TeleAtlas to provide their maps, just as standalone GPS devices do. Maps are also available from smaller vendors such as Rand McNally or from online suppliers including Google. The map view and features of most apps are broadly similar, while those from standalone GPS manufacturers such as Garmin and TomTom tend to emulate the look and feel of their portable devices.
Using Your Smartphone App
Smartphone apps work much the same as standalone GPS devices, generally relying on touchscreens and on-screen icons for navigation purposes. It's not safe to use the phone while driving, so a hands-free mount and speakerphone arrangement is best. Most apps use your phone's speaker or your hands-free to provide voice directions, and they can calculate your best route just as effectively as a standalone GPS. They can also use an address from your phone's contacts list as your destination, making it easy to find your friends or customers.
Upside and Downside
There are some things to bear in mind when you opt for a GPS app rather than a standalone GPS. Some apps stream your maps in real time, which can make a serious dent in your data plan and leave you without navigation if you're out of cellular coverage. Apps from manufacturers such as TomTom place the maps on your phone, so you'll be able to find your way as long as the phone can pick up the satellites. Some apps might require a monthly subscription, either for the program itself or for premium service such as real-time traffic data. This can sometimes make the app costlier than a separate GPS.
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