After GPS was invented, President Ronald Reagan wanted it to
be available to all people for their own use.
When a Korean Airliner was shot down for invading Russian
airspace, airplanes were required to have GPS systems
installed so that they can know when they are flying into a
danger zone.
GPS stands for Global
Positioning System.
It functions under 24 to
32 satellites orbiting the
Earth.
Each satellite transmits
microwave signals to all
GPS systems on Earth
to determine the
location, time, and
velocity.
GPS is primarily used by
civilians for navigation.
GPS Satellite
All satellites orbit in one of 6
orbital planes each having at
least 4 satellites. Each plane
is 60 degrees rotated to the
adjacent planes.
Many satellites do work
together and collaborate in
doing tasks such as locating
GPS systems on Earth.
The speed of light changes
through Earth’s atmosphere
so each satellite at a different
location can correct the error
of another satellite that sent a
signal being delayed by a
different atmosphere
condition on the planet.
Satellite Orbit
These Satellites are located 20,200
Kilometers above the ground.
They can make a revolution around the
Earth in 12 hours.
Any location at Earth is always within
range of a minimum of 6 satellites.
Satellites cannot access systems that are
on the other side of the planet.
As of today there are 31 of these satellites
functioning and orbiting our planet. A 32nd
satellite is in orbit, but has a malfunction.
Location
When a GPS is detecting the location of a GPS system on Earth, the 3
dimensions of space are taken into account.
The X-Axis determines how much left or right it is.
The Y-Axis determines how much high or low it is relative to the equator.
The Z-Axis determines how much forward or backward it is.
Time
While all GPS satellites have to consistent with Earth time, their internal
clocks have to be adjusted differently to Earth’s time.
According to Albert Einstein theory of relativity, the faster an object
moves, the slower time goes by. A GPS satellite orbits Earth at up to
speeds of 7000 mph slightly affecting the clock, so it has to be adjusted.
It takes 0.65 seconds for a signal from a satellite to reach Earth.
Velocity
Velocity is the combination of speed and direction.
This is determined by a satellite that locates the GPS system original
location, then another satellite with the system’s final location divided by the
time interval taken to reach that direction and distance.
Uses for a GPS
A GPS can be used for the following purposes:
1) Boats needing to navigate their way through sea.
2) Cars being directed through unfamiliar road maps.
3) Airline pilots needing to find out their velocity.
4) Mapmakers use this to create maps and to do some possible
land-surveying.
ERRORS!
The GPS system is not perfect and errors can happen under these
circumstances:
1) A signal can be disrupted by atmospheric conditions.
2) Signals can bounce off objects, and buildings can get in the way.
3) Terrain such as high canyon walls and mountains are able to cause
inaccuracies.