
159
159
■
Regarding Precision Accuracy
Since the GPS satellites are controlled by the US Department of Defense they do have a very
high level of accuracy, however a multipath due to reflections from buildings and so on could
cause errors to occur.
■
Regarding the Properties of the GPS Electro-Magnetic Waves and Signal
Reception
If there are any obstacles between the GPS antenna and the GPS satellite, electromagnetic-
waves cannot be received from the satellite.
It is also impossible to use GPS positioning in the following locations as at least three
simultaneous electromagnetic-waves are necessary to take measurements.
Also, if there are any obstacles around the GPS antenna, electromagnetic-waves cannot be
received from the satellite.
ATTENTION
●
Because the GPS satellite is in orbit around the earth, the reception status for the
electromagnetic waves changes depending on their position at that point in time, even if your
vehicle is in the same place. Also, electromagnetic-waves from satellites near the horizon can be
easily influenced by surrounding obstacles.
Accuracy & error calculation
●
In tunnels
●
If the immediate area is
enclosed by large objects such
as skyscrapers
●
In underground buildings and
indoor parking lots
●
In places with a lot of
overgrown trees and so on
●
Under elevated roads
●
Roads at the base of cliffs and
caves