Where am I?

Or how fast am I going? Or how do I get there from here? GPS, or Global Positioning System, isn’t just for finding the way from the airport to your hotel via the nearest Starbucks anymore.

GPS is a satellite navigation system funded and controlled by the U.S. Department of Defense. The signals from the 24 satellites orbiting Earth at 12,000 miles above us are used to compute position, velocity and time. GPS receivers are used on land sea and air, for map-making, land surveying, gauging altitude and speed with great accuracy. The satellites send radio signals to receivers in any weather, 24 hours a day. The satellites are placed so that at least 4 will be above the horizon and any given time. Three satellites are required to triangulate longitude and latitude, a fourth will figure out altitude as well.

GPS receivers are installed in cars, are hand-held devices used by mountain climbers, hikers, bicycle enthusiasts, marathon runners, glider pilots even pets. GPS receivers are often available with PDA’s, cell phones, watches and car computers.

GPS can be used by emergency services to find cell phones. Assisted GPS technology is used by cell phones because it reduces the power requirements and increases accuracy.

Some GPS units have maps, built in compasses and voice navigation. Purchasing a GPS unit is largely determined by what you’ll be using the unit for. Units start at about $100 and go up from there. Battery life, memory, screen size, whether or not its waterproof— these are just some of the criteria.

Geocaching is a popular game using hand-held GPS units to travel to a specific site and search for objects hidden by other gamers. A cashe includes a logbook to record visitor’s notes and often other items. A treasure hunt!

The type of GPS you purchase should be based on its use. With so many ways to integrate GPS in your life, you can start plotting your next adventure with ease and with the confidence that you’ll always know where you are.

Some websites to help you decide: