Through the use of GPS technology, conventional
positioning methods have been replaced.
Nowadays GPS is the tool for a large number of
kinematic and other applications. Twenty-four
(24) satellites are in orbit, of which twenty to
twenty-one (20–21) are in operation. Four (4) from
these 21 satellites are visible at any time from any
station on earth. The vertical and horizontal position
for each specific station is feasible to be obtained in the form of X, Y , Z coordinates (position
vector). The information concerning the
speed (dx=dt, dy=dt, dz=dt) of a vehicle, airplane,
ship etc. is also available all over the world, at any
time, and under all weather conditions.