App Review: Google Maps

For officers who aren't issued patrol vehicles equipped with GPS for positioning and call routing, Google Maps offers a very useful alternative. GPS will always be the best choice, but it's more costly, making Google Maps a tool that's within easy reach.

Google Maps and other mobile-device mapping/GIS (geographic information system) apps are often confused with GPS systems. They shouldn't be lumped into this category. A smart phone—with its built-in accelerometer—measures the strength of a signal emanating from cellular towers to approximate your position. An accelerometer is a tiny gyroscope-like device inside your phone that orients the device with movements in space. This is what helps your compass app know how to find true north.

The cell tower's strength is also an approximation because your device doesn't know if there are any objects between you and the tower such as a building, tree, or hill that may interfere with the point-to-point signal. In an urban area, your approximation may be off by as many as 500 yards. In a rural area, it could be off by as much as 2 miles.

In comparison, a GPS unit operates by taking conical signals from a constellation of approximately 32 satellites. Your GPS unit knows exactly where those satellites should be, so when those signals intersect, your device does the math and can pinpoint your location. As a side note, after Gulf War in 1991, the U.S. military reduced most of the selective availability and some course acquisition restrictions from the GPS satellites.

Because Google Maps isn't as precise, keep in mind that there's a lag in processing position information of up to several seconds. When using a mapping app to navigate, keep that lag in mind. Also, the more information you ask your app to deliver, such as dynamic satellite views, the longer the app will take to process your commands. Lastly, if you like to multi-task and run other apps with your mapping app, your phone will slow down.

Google Maps is the best map for the money (it's free) because it displays an incredible amount of detail.

George Rudenko is a senior officer and HazMat specialist with the Department of Homeland Security at the Los Angeles Seaport.