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Global Positioning System - How does it work?
Topic: GPS / Gallileo:
GPS is also known as Global Positioning System
Since 1960 GPS is developed by US Navy and US Air Force. In 1978 first satellite in spce. In 1983 the US government decided to open the system for civil usage. 1995: Full Operational Capability, FOC. In 2000 the formally integrated deterioration is disabled and within the exactness for civil users is increased from 100 m to 20m.
On the other hand the EU is planning an alternative system. Galileo is the first project of the European Union and the ESA( European Space Agency) and a part of TEN (Trans-European Network). The financing is organized by both organisations.
Galileo will be an alternative Positioning System against the US controlled GPS.
All system specific devices and earth stations will have been created by 2005. In 2004 Galileo wants to start the prototypes. In 2007 all satellites for Galileo will be in orbit.
Finally in 2008, it will be ready for use.
There will be 30 Galileo satellites in the altitude of 24 km. The exactness will be around 1 m.
Structure/functions of GPS:
- 24 satellites on 6 different orbits
- angle of inclination 55°#
- per orbit 4 satellites
- flight altitude 20200 km
- 5 worldwide spread earth stations for controlling und observing
- Master Control Station in USA
How does GPS work?
At present 31 active satellites are available, but on earth we are capable to receive 6 to 12 of them simultaneously.
The measuring of an precise position takes place through distance measures of several satellites on known orbits. The terms of these radio signals is countable through these distance measures. To get the precise time the satellites transmit the exact time to the receiver.
3 distance measures are sufficient to get the current position.
Method of distance measuring – one way measures
We are able to measure the position, the moving direction, the speed and the altitude.
The following information will...