 Image courtesy Consumer Guide Products A Garmin GPSMap 60CSx Handheld GPS Navigator |
Have you ever daydreamed about going on a hunt for a hidden treasure? Today, thousands of people around the world are doing just that through geocaching. Geocachers seek out treasures hidden by other players while exploring interesting locations.
At its most basic level, geocaching is a game where players use GPS receivers to track down a container, or cache. Caches may contain any number of small items, or they may only contain a logbook for players to sign to mark their find.
To understand what geocaching is all about, let's take a look at its history. In the spring of 2000, the U.S. government discontinued Selective Availability, its practice of degrading publicly-available GPS signals. Under this initiative, the GPS inserted random errors in signals for commercial receivers that made accurately determining your position impossible -- your reading could be off by as much as 300 feet. The purpose for the program was to give the U.S. military an advantage with GPS hardware. However, the military developed technology that would allow them to scramble GPS signals over sensitive areas, so Selective Availability became obsolete. Once it was switched off, it became possible for someone with a commercial GPS receiver to determine his own location with much greater accuracy. These days, you can usually determine your position within a range of 6 to 20 feet. The increase in accuracy is what makes geocaching feasible.
In the next section, we'll look at the people responsible for starting the geocaching craze.
Want to geocache, but not sure how to use a GPS receiver? Find out how a GPS receiver uses signals from satellites to pinpoint its exact
location, any time, anywhere in this HowStuffWorks GPS video. Of course, GPS receivers are used to do much more than geocache. Find out how pilots use GPS to navigate and what they do if their GPS systems fail in this video from NASA. |
