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:
Space segment:
24 satellites on 6 different orbits
angle of inclination
per orbit 4 satellites
flight altitude 20200 km
control segment:
- 5 worldwide spread earth stations for controlling und observing
Master Control Station in USA
How does GPS work?
The measuring of an precise
position takes place through distancemeasures of several satellites on
known orbits. The terms of these radio signals is countable throughthese
distance measures. To get the precise time the satellites transmit theexact
time to the receiver. 3 distance measures are
sufficient to get the currentposition. Method of distance measuring - one
waymeasures We are able to measure the position,
the moving direction, the speed andthe altitude. The following information will be
calculated by the GPSreceiver: distance and direction to the next
waypoint, changes of courses, expectedarrival, maximum speed, average speed
and many more. At least 4satellites are needed for a
three-dimensional measuring of position (longitude,latitude and altitude) 3 satellites to measure the
current position with thex-axis, y-axis and z-axis and one satellite for
thetime. The exactness of the position
ranges from 10 to 15 m.Since the 2,May 2000, it can be used by
everybodyworldwide. In excellent conditions the
precision increases to3m. The American military can
totally block civil use or canlimit it in crisis zones! The reason for that is the
earth's atmosphere, becauseradio signals are being refracted. These
are technical and economic conditions for surfacecovering of GPS use in
mobile phones, PDAs and clocks. It is possible tointegrate a satellite
detection system in nearly each electroniccomponent. 'The chances fordevelopment are
tremendous. We aren'table to foresee all possible kinds of application like
the development of computers 20 years ago, of the internet 10 yearsago.' L3
-frequency (1381.05 MHz) for the NDS(Nuclear detonation Detection system) In the
last two years various block IIF satellites werelaunched to their proper
position in orbit. They were planned to be launched in1998. They are able
to broadcast the new L3-frequency. The DoD plans to completethe system till
2009. Every year the administration plans to position 3 newsatellites. However,
it is to consider that the replacement of theexisting satellites represents
only a financial, not a technical problem. If thenew system is a great use
to individual users (e.g. aviation, navigation etc..),it is possible that
these users contribute to thefinancing. 2004:IIR-M
block satellites -M-code: military use on L1 and L2 -L2C: civil use on L2 availability of the second
signaland higher accuracy 2006beginning:
IIF block satellite -new carriersL3: only
civil use third civilsignal,
availability, accuracy Future prospect GALILEO 30satellites,
world-wide 1meter
exactly phases -Developmentphase
2002-2005 -Establishment phase
2006-2007 -startingfrom 2008 *according to news of the day reports American armedforces will be
able to switch off likewise in crisis and conflicts the Europeansatellite
navigation system GALILEO, like it already happens with the Americanglobal
positioning system (GPS). independence smaller
susceptibility to interference self-sufficiency control say security/integrity (military)
efficiency accuracy higher
security of the overall system (GPS + GALILEO) higher
accuracy and breakdown resistance (integrity) equalsay
and control on the part of the European Union satellite
navigation as a billion-market of the future GALILEOas an element in the total strategy of the
European Unio
Precision of thesystem
Safety political reasons andadvantages of
GALILEO
