Thales NSS 100S-1 Component Maintenance Manual With Illustrated Parts List page 36

3. Operation
A. Principle of the GPS System
The GPS system is divided into 3 segments:
- The space segment (the satellites)
- The ground segment (the control stations)
- The user segment (the Receiver Processor Unit, the Antenna Coupler Unit
and, in some cases, the PreAmplifier Unit).
Note: The characteristics of the space and ground segments are defined in
STANAG document 4294-1.
(1) Space segment
This segment comprises the various satellites staggered in relation to
each other so that reception from at least 4 satellites is possible
anywhere in the world.
The earth revolution time of each satellite is 12 hours.
Each satellite calculates and maintains its position by means of the
ground segment.
GPS time, the date, the ephemerides of its orbit and the GPS network
(2) Ground segment
This segment comprises a main station and various relay stations instal-
led throughout the world.
(3) User segment (see Figure 1)
It comprises:
- An Antenna Coupler Unit
- A PreAmplifier Unit
- A Receiver Processor Unit
The user segment analyzes the signals transmitted by (a maximum of ) 8
satellites and computes the aircraft position.
COPYRIGHT SEXTANT Avionique 1995
c
The document reference is online, please check the correspondence between the online documentation and the printed version.
COMPONENT MAINTENANCE MANUAL
C17004
It transmits, to the user segment, its position, the
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OCT 16/95