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We tend to use “GPS” the way we use “Kleenex” or “Band-Aid”—as a brand name substitute for the generic “satellite navigation system.” But the Global Positioning System is actually quite specific: It’s a constellation of 27 satellites and a global network of control facilities on the ground developed and operated by the Defense Department.
There are other sat-nav systems, though, and since 2011, most sat-nav consumer devices, including Apple’s and Samsung’s, have receivers for both the U.S. GPS and Russia’s Global Navigation Satellite System, or GLONASS—a 24-satellite network operated by the Armed Forces of the Russian Federation. (There are other regional systems, like the Indian Regional Navigation Satellite System and China’s BeiDou Navigation Satellite System; but GPS and GLONASS are the only fully global networks.) Continue reading