Global Positioning System (GPS) receivers work by receiving signals from GPS satellites; each signal has the time it was broadcast and the orbital information of the satellite. A specialized chip on the receiver or a specialized program in a smartphone, convert this information into a set of coordinates. These coordinates get used in a lot of ways, some of which are a little surprising.
Item Tracking Systems
GPS receivers with integrated antennas can be made the size of a stick of chewing gum. Integrated with a small cell-phone transmitter, it can send out an update with GPS coordinates. Depending on how this update is programmed, it can notify a business owner about the location of delivery vehicles, be used to track a stolen item, like a vehicle or laptop, and even track a missing pet or child.
911 Services for Cell Phones
Since 2002, the U.S. Federal Communications Commission has mandated GPS capabilities in all cell phones and cell-phone towers. For land lines, every phone number is tied to a physical location; for cell phones prior to GPS, positional information for 911 calls was determined by cell-tower triangulation. GPS coordinates are much more accurate, allowing positional fixes down to 10 yards and making it much easier for emergency responders to get to people after a disaster or car accident.
Aviation and Maritime Transport
GPS coordinate systems are a critical component of autopilot systems, and for ocean-going transport. In both of these environments, GPS tracking is used to set a course between two points without worrying about intervening landmarks. They greatly reduce navigation errors, overall safety (by keeping the ship or plane on its prerecorded and expected route) and even fuel economy, by allowing routes to work with tailwinds for planes and favorable currents for ships.
The most common use of GPS tracking is turn-by-turn navigation for cars and pedestrians in cities. This technology is used by taxi drivers, truck drivers and private individuals. The typical turn-by-turn navigation device is a tablet display mounted on a dashboard. Increasingly, this functionality is shifting towards smartphones as another application.
Hiking and Geocaching
Handheld GPS devices have been used as hiking aids -- including marking a point as a base camp to return to -- since the late 1990s. A related sport is called geocaching, where a website posts the GPS coordinates of a cache of objects, and players use their GPS devices to find the caches, usually to replace an item in the cache with something the hiker brought.
The U.S. Geological Survey uses GPS data to give real-time tracking of tectonic activity, using additional sensors on site and long observation periods to track things like continental drift, the sliding of tectonic plates, and earthquakes and upheavals that may foretell a volcanic eruption.
- Thinkstock/Comstock/Getty Images