Leica Geosystems GPS Basics - Manual (Page 8)

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GPS Basics -1.0.0en System Overview
4
2.2 The Control Segment
The Control Segment consists of one
master control station, 5 monitor sta-
tions and 4 ground antennas distributed
amongst 5 locations roughly on the
earth’s equator.
The Control Segment tracks the GPS
satellites, updates their orbiting position
and calibrates and sychronises their
clocks.
A further important function is to deter-
mine the orbit of each satellite and
predict it’s path for the following 24
hours. This information is uploaded to
each satellite and subsequently broad-
cast from it. This enables the GPS
receiver to know where each satellite
can be expected to be found.
The satellite signals are read at Ascen-
sion, Diego Garcia and Kwajalein. The
measurements are then sent to the
Master Control Station in Colorado
Springs where they are processed to
determine any errors in each satellite.
The information is then sent back to the
four monitor stations equipped with
ground antennas and uploaded to the
satellites.
H a w a i i
C o l o r a d o S p r i n g s
A s c e n s i o n
D i e g o G a r c i a
K w a j a l e i n
Control Segment Station Locations