Global Positioning System And History
For an overview on Global Positioning System (GPS) you have come to the right place. GPS was originally used solely by the U.S. military for position finding, navigation, and to aim weapons accurately. Shortly after the system was put into place, the global positioning system was made available to the civilian community.
The first four satellites of the system were put into orbit in 1978. Now, there are a total of 24 satellites that make up the global positioning system. They are divided into 6 orbital planes with 4 satellites in each plane. This is so that anywhere on the Earth, you should be able to receive the signals from enough satellites to obtain an accurate position.
To understand the impact of the global positioning system and history, one must realize that this has completely changed the way man navigates the earth. Prior to GPS and some earlier prototype systems, man's most often used navigation system was by using the stars in the sky.
DoD Global Positioning Policy
Even today, however, the DoD global positioning policy has been to provide less accurate signals to the civilian community. The military has the capability to accurately navigate to less than 10 meters, while the civilian community can only navigate to a 100 meter accuracy. There is the expectation that the DoD global positioning policy will change so the civilian community gets the same accuracy as the military.
To improve the accuracy of the civilian GPS signals, other technologies have been developed such as the Wide Area Augmentation System (WAAS) and Differential GPS (DGPS).