| The Global Positioning System, commonly called | | | | The GPS system became fully functional in 1985. |
| GPS, is a navigational system that uses satellites | | | | Today it is used for navigating on land, sea and |
| and computers to determine the latitude and | | | | air. It is also used for mapmaking, land surveying |
| longitude of a receiver on Earth. This is done by | | | | and scientific research. |
| computing the time difference for signals from | | | | Over the last fifteen years, the accuracy of the |
| different satellites to reach the receiver. | | | | GPS signal has improved steadily. Today, a GPS |
| GPS is the only satellite navigation system that is | | | | system can accurately pinpoint the receiver on |
| fully functional. It uses a collection of more than | | | | Earth to almost five meters of its exact location. |
| twenty-four satellites to send radio signals to | | | | However, further improvements and |
| electronic GPS receivers. By doing so, the | | | | developments may increase the accuracy to |
| satellites are able to find the correct location of | | | | about 1 cm of the receiver. This can be done |
| the receivers. They get the exact longitude, | | | | using techniques such as differential GPS. A GPS |
| latitude and altitude of the receiver. GPS systems | | | | also gives an extremely precise time reference |
| work around the clock under any weather | | | | which is useful in some scientific experiments. |
| conditions. | | | | |