Global Positioning System. Artist's conception of GPS Block II-F satellite in Earth orbit. The Global Positioning System (GPS) is a space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.[1] The system provides critical capabilities to military, civil and commercial users around the world. It is maintained by the United States government and is freely accessible to anyone with a GPS receiver.
The GPS project was developed in 1973 to overcome the limitations of previous navigation systems,[2] integrating ideas from several predecessors, including a number of classified engineering design studies from the 1960s. GPS was created and realized by the U.S. Department of Defense (DoD) and was originally run with 24 satellites. It became fully operational in 1995. History[edit] Predecessors[edit] Official logo for NAVSTAR GPS Development[edit] Title Page. The Global Positioning System, also known as the GPS, is made up of a network of around twenty-four satellites sent into orbit by the Department of Defense of the US. It is a navigation system which was initially meant to be used for US military purposes. However, in the 1980’s, civilians were allowed access to the system, too, by the US government. The Global Positioning System is able to function in any type of weather, in any location world-wide, at any time during the day. The use of GPS requires no subscription fees or set-up charges; it is free to all civilians.
The GPS is made up of 24 satellites that orbit the earth. These satellites are located about 12,000 miles above the earth’s surface. Title Page. Each GPS satellite sends out two low power radio signals which are designated L1 and L2. GPS used by civilians use the L1 signals, which have a frequency of around 1575.42 MHz in the UHF band. Signals “travel by line of sight,” ( which means that though they can pass through clouds, glass, and plastic, they are unable to make it through most other solid objects. Signals are given a pseudorandom code which serves as an ID used to identify which satellite the information is coming from.
Each satellite continuously sends out what is known as ephemeris data. How GPS Receivers Work" Our ancestors had to go to pretty extreme measures to keep from getting lost. They erected monumental landmarks, laboriously drafted detailed maps and learned to read the stars in the night sky. Things are much, much easier today. For less than $100, you can get a pocket-sized gadget that will tell you exactly where you are on Earth at any moment. As long as you have a GPS receiver and a clear view of the sky, you'll never be lost again. In this article, we'll find out how these handy guides pull off this amazing trick. As we'll see, the Global Positioning System is vast, expensive and involves a lot of technical ingenuity, but the fundamental concepts at work are quite simple and intuitive. When people talk about "a GPS," they usually mean a GPS receiver.
Each of these 3,000- to 4,000-pound solar-powered satellites circles the globe at about 12,000 miles (19,300 km), making two complete rotations every day. Global Positioning System.