GPS, or the Global Positioning System, offers a real-time position fix with an accuracy of
3 to 100 meters on a 24 hour per day basis. It also offers a way to determine time to a
precision of better than a few hundred nanoseconds almost anywhere on the surface of the earth.
The GPS system consists of a constellation of 24 satellites. These satellites orbit the earth
at an altitude of about 10,900 miles and at an inclination of 55 degrees. This orbit translates
to an orbital period of 12 hours. The orbits are distributed around the earth in such a way
that at least 6 satellites are always visible from virtually any point on the surface of the
earth. This provides a means of precisely determining the position of the user in longitude,
latitude, and altitude. These are capabilities that are revolutionizing many areas
of life -- including entertainment. See our new section below on Geocaching!
GPS is the widest used application of Spread Spectrum -- period! Peter Dana, formerly
of the University of Texas at Austin and now at the University of Colorado, has compiled a
comprehensive GPS information site:
The sport of geocaching (a form of high-tech treasure hunting) is rapidly catching
on internationally, with caches in more than 180 countries. All you need to participate
is a GPS device and a sense of adventure. We've tried it and we love it!
Below are links to some of the best sites to help you locate the latest caches in your area,
find out how to hide your own cache, and information on how to get started in this fun and
exciting sport.
Geocaching.com — The Official
Global GPS Cache Hunt Site. Lots of information and tips.
