In the age old days of yore, when there were no satellites floating through space in earth orbit, people were forced to navigate using “maps”. Now that GPS receivers and onboard navigational computers have been linked, companies like Garmin guarantee that you’ll never get lost on your way to a relative’s house again. However, you’re still dependent on those satellites in orbit. If you’ve got crappy sky views, or are driving through a canyon, you’re stuck.
Now Google has launched an application for their mobile maps product that relies on triangulation between cell phone towers to do exactly the same thing. Using signal time of arrival, the mobile device can pinpoint your location to within the bounds of accuracy needed for automobile navigation. I wouldn’t use this software for trying to find one particular spot (i.e., no geocaching) but for following a road map, pretty nice. This application will suffer from some of the same drawbacks as GPS, especially the low-coverage problem (not a lot of cell towers in the deep dark reaches of rural roadways), but it offers a second solution to the navigation problem.
This is not a new idea, but Google is, as usual, one of the first organizations to push it out into common use. There have been proposals to use cell tower triangulation for 911 geolocation, but I don’t know if there has been any progress on that front.