Man has always speculated about what lies beyond his immediate circle of knowledge. Many a journey has been taken and many a new land has been discovered all because of man’s curiosity. The uncertainties faced and risks taken in the name of adventures and travel has claimed many lives. Navigation and maps are vital to these activities.
Luckily for us, we live in an age of new and innovative ways for technology to help us and one of them is the GPS system.
Global Positioning System (GPS) is a worldwide navigation system formed from a constellation of 24 satellites and the associated ground stations. There can be more than 24 operational satellites; new ones are launched periodically to replace older satellites.
Each satellite orbits continually about the same ground track (as the earth turns beneath them) once per day, at an altitude calculated to ensure the satellite repeats the same track over all points approximately each 24 hours (actually 4 minutes earlier each day).
There are six orbital planes, equally spaced (60 degrees apart), and inclined at about fifty-five degrees with respect to the equatorial plan. The GPS system uses “man-made stars” as reference points to parse accurate positions to within meters.
The GPS system in it’s entirety is comprised of a network of satellites, signals, support personnel, ground based hardware and software, which make possible the establishment of one’s precise location on the Earth’s surface. The Global Positioning System is funded by and overseen by the U. S. Department of Defense (DOD). While there are many thousands of civil users of GPS world-wide, the system was designed for and is operated by the U. S. military.
The accuracy of location measurements using the global positioning system depends on the GPS receiver. High-end, survey-grade GPS receivers can determine locations precise to within centimeters. But even low-end, handheld consumer receivers, can be accurate to within fifteen meters. GPS receivers have been miniaturized to just a few integrated circuits and so are becoming economical and readily available.
The first commercial global positioning system units were precise for only about 100 meters because the military scrambled the signal--a program called Selective Availability. In the year 2000, the U.S. government removed Selective Availability, improving the accuracy of even basic handheld units to within fifteen meters. Today, with additional information from ground based correction services such as WAAS WAAS (Wide Area Augmentation Service) or U.S. Coast Guard differential GPS beacons, accuracy can be improved even further.
Lyne Doxley is a contributor to Fountia.com, where you can read tips about how to install a wireless PCI card, Bluetooth wireless and other wireless topics.
Written By: Lyne Doxley
