Gps Satellite

By Author: Romek
Total Articles: 6
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Global Positioning System (GPS) is currently the only completely functional global navigation satellite system (Ford Global Navigation Satellite System - GNSS). GPS consists of 24 satellites deployed in Earth orbit, which sends radio signals to the surface of the Earth. GPS receivers are based on these radio signals those can determine its exact position - altitude, latitude and longitude - anywhere on the planet during day or night, in all weather conditions.

GPS has a great application as a global service in various areas, commercial and scientific purposes: navigation at sea, land and air, soil mapping, making maps, determining the time, the detection of earthquakes and the like. GPS was developed by the U.S. Department of Defense named NAVSTAR GPS in the DARPA (some sources say that the abbreviation of the NAVSTAR Navigation Signal Timing and GPS ranging, while others say that it is randomly selected sound name given by John Walsh, a person who had a role in deciding the fate of the project).

In the beginning, GPS was used exclusively for military purposes, but it was later made to be available and free to ...
... all as a public good. Annual maintenance costs of the system are about 750 million U.S. dollars.

Basics:-

GPS Receiver is a device that calculates its position based on the measurement of the distance of three or more GPS satellites. Each satellite emits microwave radio signal sequence that is known to the receiver. When the receiver gets the signal, he is able to determine the time elapsed since the broadcast radio signal from the satellite came to the reception at his position. Distance from the satellite receiver is calculated on the basis of the time, since the radio signal travels at a known speed. The signal also carries information about the current position of satellites from which he is broadcasted. If you know the distance from the satellite receiver and satellite positions, it is known that the receiver is located somewhere in the sphere of specific dimensions in the center of satellite. Since the position of three satellites is known, the receiver distance from each of them, we can determine the position of the receiver by using the procedure of alteration. This is based on the fact that the three spheres intersect at most two points (one of which usually does not make sense).

This approach involves working with the clocks on all satellites while the receiver is completely synchronized to the time gap between the known sequence of signals from the satellite and the receiver's which is accurately measured. On the satellites there are atomic clocks those are very precise and expensive. However, the receiver has a far less accurate clock, a crystal oscillator. Lack of precision is solved by measurement of distance from another satellite. The clock on the receiver has the same mistake of the time and the space during calculation of distance from all four satellites. It can be calculated for how much to adjust the clock to create the intersection of all four spheres at the same point. In this way, the clock in the receiver continuously adjusts. One of the applications of GPS is very precise calculation of time and clock synchronization. For More Information Please visit. http://www.gps-teknik.se/