| The first time the GPS unit was tested under fire, | | | | longitude of the GPS unit to an accuracy of |
| it performed like a battle-tested veteran. The | | | | between one and five meters, and may contain |
| GPS unit was an essential tool in the success of | | | | its altitude as well. |
| the first Gulf War in 1991, when it enabled the US | | | | Most GPS units come loaded with mapping |
| military to successfully map enormous expanses | | | | software, because while knowing where you are |
| of unfamiliar desert terrain. The navigation made | | | | may be useful, knowing how to get from where |
| possible by the use of the GPD unit was a | | | | you are to where you want to go can be much |
| cornerstone of the successful Desert Storm | | | | more useful. The more detailed the maps on a |
| effort. | | | | GPS unit's software, the more precisely you will |
| The GPS unit has come a long way from those | | | | be able to map your surroundings. Some GPS |
| days, and is now as essential a part of civilian life | | | | units even have voice capability to give you |
| as it was for the military in Desert Storm. | | | | continuous directions as you proceed on your |
| Estimates are that there are over five hundred | | | | way. |
| different types of GPS units available in prices | | | | Limitations Of GPS Units |
| ranging from below $100 to over $15,000, | | | | GPS units do have their limitations; many earlier |
| depending on the sophistication of their | | | | models could not receive satellite transmissions if |
| technologies. | | | | their view were obstructed by dense foliage, |
| Basics Of GPS Technology | | | | canyon walls, or tall buildings; and if they were |
| A GPS unit operates by sending an electronic | | | | being used indoors had to have external antennas. |
| signal to a group of twenty-one satellites in orbit | | | | GPD units are available in a wide variety of sizes |
| nearly twelve thousand miles above the Earth; the | | | | from backpacker's watches, to handheld PDAs |
| satellites will analyze the signal and up to four of | | | | and cell phones, to vehicular units. Miniature GPS |
| them will return location information back to the | | | | units have been designed to implant in, and track |
| unit. The information will include the latitude and | | | | the movements of, endangered animals. |