Global Positioning System Reference
In-Depth Information
Frequency stability
021220.011
Specification
Tau
1.00e
Sigma
4.99e
02
+
+
+
+
+
+
+
+
+
+
−
−
−
−
−
−
−
−
−
−
14
2.00e
02
3.42e
14
4.00e
02
2.55e
14
Measurement
1.00e
03
1.61e
14
2.10e
03
1.07e
14
4.60e
03
7.53e
15
1.00e
04
6.16e
15
2.15e
04
5.89e
15
4.64e
04
6.21e
15
1.00e
05
4.87e
15
10
4
10
5
10
2
10
3
2
2
2
Average time, t, seconds
Figure 10.13
GALILEO PHM and stability results.
capability to carry up to six SVs per launch, and small launch vehicles to carry one
or two SVs.
The currently identified launch vehicle configurations are as follow
:
•
Ariane 5: six satellites;
•
Proton: six satellites;
Soyuz 2 ST: one or two satellites;
•
Zenit: one or two satellites with the possibility to extend up to three or four.
•
10.5.2 Ground Segment
The GALILEO Ground Segment comprises two major ground systems, the Ground
Control Segment (GCS) and the Ground Mission Segment (GMS). It is implemented
through:
•
A global network of GALILEO Sensor Stations (GSSs) used for one-way rang-
ing measurements and monitoring of the signal in space of the GALILEO sat-
ellites for orbit determination, time synchronization, integrity determination
and supervision of provided services;
•
A global network of TT&C stations for control of the GALILEO satellites and
constellation;
•
A global real-time oriented network of uplink stations (ULSs) for mission data
(navigation, integrity, SAR, and other navigation-related services);
•
An interconnecting high-performance communication network;
•
Two geographically redundant GCCs for all the centralized processing, moni-
toring, and control.
LEOP and in-orbit testing (IOT) activities will be supported through renting or
refurbishing of an existing infrastructure from LEOP and IOT service providers.
Figure 10.14 provides an illustration of the physical architecture concept.
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