3. Alternatives to US GPS and future
a. Why alternatives ?
GPS totally belongs to the US Department of Defense so they have a total control
on this system.
- they can decide to stop completely the GPS at any moment, especially
during a crisis. It already happened
during the Gulf War : only the US Army could use the GPS.
- they can also decide to degrade precision
- there can be a mechanical breakdown, that would paralyze
navigation on the Earth
GPS also has several major technical limitations we will discuss later, and lacks of some features like a service garantee
and accountability, because they are incompatible with the military objectives.
b. GLONASS : Russia enters the battle...
...and quickly surrenders : USA 1 - RUSSIA 0
GLONASS = GLObal Navigation Satellite System.
GLONASS was created by the Russian Army.
Caracteristics
Same as GPS except the timezone reference and some
very minor differences.
...So, what's the problem ?
Drawbacks
- Official webpage down (Error 404, official Russian web
page does not exist anymore)
- Approximatively 5 or 6 working satellites remaining at this time.
Russia does not have enough money to maintain its system.
- As a result, Glonass has not generated any strong civil application.
c. Galileo : The European Union strikes back
Galileo is a civil Global Navigation System,
developped by the 15 countries of the European Union, in close
cooperation with the European Space Agency (ESA).
Civil purposes
It is NEITHER in the hands of
a department of justice NOR in the hands of any army.
It does not aim at being a strategical weapon in a war.
Its goal is just to be useful for everyday life.
Some numbers concerning Galileo :
- will be ready in 2008
- costs 3.4 millions of Euros
- has been approved by the 15 countries on March, 17th 2002
- features 30 satellites, at 24 000 km over your heads
Technical limitations of the GPS that will be corrected in Galileo
- Varying position accuracy, depending of time and place : sometimes, the
accuracy is to only several dozen meters
- the reliability leaves something to be desired :
regions at high latitudes, crossed by many aviation routes, do not
have dependable coverage
Galileo offers superior and constant accuracy, as well as better reliability
(it includes an integrity message so that you can detect errors).
d. Towards a unified navigation system ?
GPS + Glonass + Galileo = G.N.S.S. (Global Navigation by Satellite System)
