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1.3.2 THE CONTROL SEGMENT
The control segment consists of a master control station, five reference stations and three data up-loading stations
in locations all around the globe.
The reference stations track and monitor the satellites via their broadcast signals. The broadcast signals contain the
ephemeris data of the satellites, the ranging signals, the clock data and the almanac data. These signals are passed
to the master control station where the ephemerides are re-computed. The resulting ephemerides corrections and
timing corrections are transmitted back to the satellites via the data up-loading stations.
1.3.3 THE USER SEGMENT
The user segment such as the NovAtel GPSCard receiver, consists of equipment which tracks and receives the
satellite signals. The user equipment must be capable of simultaneously processing the signals from a minimum of
four satellites to obtain accurate position, velocity and timing measurements.
1.4 GLONASS SYSTEM DESIGN
As with GPS, the GLONASS system uses a satellite constellation to ideally provide a GLONASS receiver with six
to twelve satellites at most times. A minimum of four satellites in view allows a GLONASS receiver to compute
its position in three dimensions, as well as become synchronized to the system time.
The GLONASS system design consists of three parts:
•
The Space segment
•
The Control segment
•
The User segment
All these parts operate together to provide accurate three dimensional positioning, timing and velocity data to users
worldwide.
1.4.1 THE SPACE SEGMENT
The Space Segment is the portion of the GLONASS system that is located in space, that is, the GLONASS satellites
and any ancillary spacecraft that provide GLONASS augmentation information (i.e., differential corrections,
integrity messages, etc.). This segment is composed of the GLONASS satellites which, when complete, will
consist of 24 satellites in three orbital planes, with eight satellites per plane, see Figure 1.3, Page 12. Following
are points about the GLONASS space segment.
GPS/GLONASS Receiver User Manual Rev 1
Figure 1.2 View of GPS Satellite Orbit Arrangement
1 Introduction
11
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