The system
tells you your exact position anywhere on
the surface of the Earth
The only
fully functional satellite navigation
system.
Created by
the US Dept of Defense for military
navigation. In the 1980's the system became
available to civilian use!
It works
24/7, day/night, rain/shine.
It works
anywhere on Earth: land, sea or air.
There are 27 solar powered satellites in the
system in which 24 are working. The others
are extra in case one breaks.
The first satellite was launched in 1978.
The full constellation was completed in
1994.
Each satellite is 17 feet in diameter with
panels extended and weighs about 2000 lbs,
as much as a bison!
A satellite's lifespan is about 10 years.
The receiver is
what you use to tap into the GPS system
Information
transmitted to the receiver from the
satellite includes where the satellite
should be and the correct date and time.
Receivers
measure time delay between when the
satellite sent a signal and the time it is
received. The delay multiplied by the speed
of light equals the distance to the
satellite.
Receivers use
the distance from at least three satellites
to determine its position on the Earth. This
is called 'Triangulation' (explain in
further detail on next page).
The receiver
needs a direct line of sight to the
satellite.
Solid objects
like a lot of trees can block the signal.
