Galileo Architecture: Difference between revisions

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GALILEO
Title	Galileo Architecture
Edited by	GMV
Level	Basic
Year of Publication	2011

The Galileo System will be an independent, global, European-controlled, satellite-based navigation system and will provide a number of guaranteed services to users equipped with Galileo-compatible receivers.

To ensure GALILEO services, a specific architecture is deployed, that will consist of 30 satellites, to be deployed in a staggered approach, and the associated ground infrastructure.^[1] The Galileo system is divided into three major segments: Space Segment, Ground Segment and User Segment.

Introduction

Galileo Architecture

The Galileo infrastructure will be composed of:^[2]

A constellation of 30 satellites in Medium-Earth Orbit (MEO). Each satellite will contain a navigation payload and a search and rescue transponder;
a global network of Galileo Sensor Stations (GSS) providing coverage for clock synchronisation and orbit measurements;
two Control Centers and two Launch Early Operations (LEOP) Centers;
a network of Mission Uplink stations;
several Telemetry, Tracking and Control (TT&C) stations.

This infrastructure is organized in two segments, the Space Segment and the Ground Segment, to be complemented by the users receivers, which compose the User Segment.

GALILEO Space Segment

Galileo Space Segment

The main functions of the Galileo Space Segment are to generate and transmit code and carrier phase signals with a specific Galileo signal structure, and to store and retransmit the navigation message sent by the Control Segment. These transmissions are controlled by highly stable atomic clocks on board the satellites.

When Galileo is fully operational, there will be 30 satellites in Medium Earth Orbit (MEO) at an altitude of 23,222 kilometers. The satellites will occupy each of three orbital planes inclined at an angle of 56° to the equator. The satellites will be spread evenly around each plane and will take about 14 hours to orbit the Earth. One satellite in each plane will be a spare, on stand-by should any operational satellite fail.^[1]

Highly accurate atomic clocks are installed on these satellites. Each of the 30 satellites in the Galileo system will have two of each type of clock on board, a rubidium and a hydrogen maser clock. The frequency is at around 6 GHz for the rubidium clock and at around 1.4 GHz for the hydrogen clock. The Galileo system uses the clock frequency as a very stable reference by which other units can generate the accurate signals that the Galileo satellites will broadcast. The broadcast signals will also provide a reference by which the less stable user receiver clocks can continuously reset their time.

The satellites are deployed gradually according to the Galileo Program schedule.

GALILEO Ground Segment

The Galileo Ground Segment is the responsible for the proper operation of the GNSS system. Its basic functions are:

To control and maintain the status and configuration of the satellite constellation.
To predict ephemeris and satellite clock evolution.
To keep the corresponding GNSS time scale (through atomic clocks).
To update the navigation messages for all the satellites.

The Galileo Ground Segment constitutes the major system element controlling the entire constellation, the navigation system facilities and the dissemination services. It is composed of two Ground Control Centers (GCC), five Telemetry, Tracking and Control (TT&C) stations, nine Mission Uplink Stations (ULS), a global network of Galileo Sensor Stations (GSS)^[3] and the European GNSS Service Centre (GSC)^[4].

The Galileo Ground Segment is decomposed into the Galileo Control System and the Galileo Mission System. The Galileo Control System (GCS), as the responsible for satellite constellation control and management of Galileo satellites, provides the telemetry, telecommand and control function for the whole Galileo satellite constellation. The Galileo Mission System (GMS) is responsible for the determination and uplink of navigation and integrity data messages needed to provide the navigation and UTC time transfer service.

GALILEO User Segment

The Galileo User Segment is composed by Galileo receivers. Their main function is to receive Galileo signals, determine pseudoranges (and other observables), and solve the navigation equations in order to obtain their coordinates and provide a very accurate time.

Three receiver development activities have been initiated within the Galileo programme, addressing the different needs of the system development process and covering the range of signals and services that will be offered. Activities in receiver development are in the following areas:^[1]

test user segment;
receivers for the signals transmitted by the first experimental satellites;
receivers for the Galileo receiver chain.

Notes

References

^ ^a ^b ^c ESA Galileo web page
^ J. Sanz Subirana, JM. Juan Zornoza and M. Hernández-Pajares, Global Navigation Satellite Systems: Volume I: Fundamentals and Algorithms
^ Official Journal of the European Union of 23 of February 2012 (2012/117/EU), Annex 1
^ http://www.gsc-europa.eu/

[EsaGalileoweb-1] ESA Galileo web page

[GNSS-Book-2] J. Sanz Subirana, JM. Juan Zornoza and M. Hernández-Pajares, Global Navigation Satellite Systems: Volume I: Fundamentals and Algorithms

[3] Official Journal of the European Union of 23 of February 2012 (2012/117/EU), Annex 1

[4] ttp://www.gsc-europa.eu/

[1]

[2]

[3]

[4]

@@ Line 1: / Line 1: @@
 {{Article Infobox2
 |Category=GALILEO
-|Title={{PAGENAME}}
+|Editors=GMV
-|Authors=GMV
 |Level=Basic
 |YearOfPublication=2011
 |Logo=GMV
+|Title={{PAGENAME}}
 }}
+The [[GALILEO General Introduction|Galileo]] System will be an independent, global, European-controlled, satellite-based navigation system and will provide a number of guaranteed services to users equipped with Galileo-compatible receivers.
-The GALILEO System will comprise global, regional and local components. The global component is the core of the system, comprising the satellites and the required ground segment. To ensure GALILEO services, a specific architecture is deployed, that will consist of 30 satellites, to be deployed in a staggered approach, and the associated ground infrastructure.<ref name="EsaGalileoweb">[http://www.esa.int/esaNA/galileo.html ESA Galileo web page]</ref>
+To ensure GALILEO services, a specific architecture is deployed, that will consist of 30 satellites, to be deployed in a staggered approach, and the associated ground infrastructure.<ref name="EsaGalileoweb">[http://www.esa.int/esaNA/galileo.html ESA Galileo web page]</ref> The Galileo system is divided into three major segments: [[GALILEO Space Segment|Space Segment]], [[GALILEO Ground Segment|Ground Segment]] and [[GALILEO User Segment|User Segment]].
-The Galileo system is divided into three major segments: [[GALILEO Space Segment|Space Segment]], [[GALILEO Ground Segment|Control Segment]] and [[GALILEO User Segment|User Segment]].
 ==Introduction==
-[[File:GalileoFOCArchitecture.JPG|350px|Galileo Architecture|thumb]]
+[[File:GalileoFOCArchitecture.JPG|300px|Galileo Architecture|thumb]]
-The Galileo global infrastructure, the core of the system, will be composed of:
+The Galileo infrastructure will be composed of:<ref name="GNSS-Book ">J. Sanz Subirana, JM. Juan Zornoza and M. Hernández-Pajares, ''Global Navigation Satellite Systems: Volume I: Fundamentals and Algorithms''</ref>
-*	A constellation of 30 satellites in Medium-Earth Orbit (MEO). Each satellite will contain a navigation payload and a search and rescue transponder;
+* A constellation of 30 satellites in Medium-Earth Orbit (MEO). Each satellite will contain a navigation payload and a search and rescue transponder;
-*	around 30 sensor stations (GSS);
+* a global network of Galileo Sensor Stations (GSS) providing coverage for clock synchronisation and orbit measurements;
-*	2 Control Centres & 2 Launch Early Operations (LEOP) Centers;
+* two Control Centers and two Launch Early Operations (LEOP) Centers;
-*	9 Mission Uplink stations;
+* a network of Mission Uplink stations;
-*	5 Telemetry, Tracking and Control (TT&C) stations.
+* several Telemetry, Tracking and Control (TT&C) stations.
-Galileo Regional Component:  This component complements the global services of Galileo, which involves the delivery of worldwide integrity for Galileo satellites. The Galileo Regional Component includes the EGNOS system, providing integrity and deferential corrections for GPS and GLONASS through geostationary satellites, as well as several External Region Integrity Systems (ERIS), implemented and operated by organizations, countries or groups of countries outside of Europe to obtain integrity services independent of Galileo.
+This infrastructure is organized in two segments, the [[GALILEO Space Segment|Space Segment]] and the [[GALILEO Ground Segment|Ground Segment]], to be complemented by the users receivers, which compose the [[GALILEO User Segment|User Segment]].
-In this way, different integrity-monitoring stations collect data and send them to a Processing Centre to compute regional corrections and integrity data. The regional integrity data is uplinked to the Galileo satellites and broadcast to the service area users via a dedicated channel. A maximum number of five regions will be covered due to the limitations in the capacity of the message.
-Galileo Local component:  This component allows enhanced accuracy, availability and integrity in local areas as airports, maritime harbours, etc., with more demanding requirements than those available from the global or regional components (e.g., integrity). These special services are met through the use of local augmentation elements.
 ==GALILEO Space Segment==
 [[File:Galileo Space Segment.jpg|250px|Galileo Space Segment|left|thumb]]
-The main functions of the [[GALILEO Space Segment|Galileo Space Segment]] are to generate and transmit code and carrier phase signals with a specific [[GALILEO Signal Structure|Galileo signal structure]], and to store and retransmit the navigation message sent by the [[GALILEO Ground Segment|Control Segment]]. These transmissions are controlled by highly stable atomic clocks on board the satellites.
+The main functions of the [[GALILEO Space Segment|Galileo Space Segment]] are to generate and transmit code and carrier phase signals with a specific [[GALILEO Signal Plan|Galileo signal structure]], and to store and retransmit the navigation message sent by the [[GALILEO Ground Segment|Control Segment]]. These transmissions are controlled by highly stable atomic clocks on board the satellites.
-When Galileo is fully operational, there will be 30 satellites in Medium Earth Orbit (MEO) at an altitude of 23,222 kilometres. The satellites will occupy each of three orbital planes inclined at an angle of 56° to the equator. The satellites will be spread evenly around each plane and will take about 14 hours to orbit the Earth. One satellite in each plane will be a spare, on stand-by should any operational satellite fail.<ref name="EsaGalileoweb"/>
+When Galileo is fully operational, there will be 30 satellites in Medium Earth Orbit (MEO) at an altitude of 23,222 kilometers. The satellites will occupy each of three orbital planes inclined at an angle of 56° to the equator. The satellites will be spread evenly around each plane and will take about 14 hours to orbit the Earth. One satellite in each plane will be a spare, on stand-by should any operational satellite fail.<ref name="EsaGalileoweb"/>
-Based on the award of the contracts for the first order of satellites, the launch services, the system support services and the operations, the [[Wikipedia:European Commission|European Commission]] announced the Initial Operational Capability (IOC) with 18 operational satellites and three initial services to be provided in 2014/2015: an initial [[GALILEO Open Service|Open Service]], an initial [[GALILEO Public Regulated Service|Public Regulated Service]] and an initial [[GALILEO Search and Rescue Service|Search and Rescue Service]].<ref>Commission awards major contracts to make Galileo operational early 2014,  [http://europa.eu/rapid/pressReleasesAction.do?reference=IP/10/7 IP/10/7], Brussels, 7 January 2010.</ref> At this stage, accuracy and availability will not yet have reached their optimum level, the [[GALILEO Safety-of-Life Service|Safety-of-Life Service]] and the [[GALILEO Commercial Service| Commercial Service]] will be tested and will be provided as the system reaches full operational capability with the 30 satellites.<ref name="Mid-term review">[http://ec.europa.eu/enterprise/newsroom/cf/_getdocument.cfm?doc_id=6321 Mid-term review of the European satellite radio navigation programmes]</ref>
+Highly accurate atomic clocks are installed on these satellites. Each of the 30 satellites in the Galileo system will have two of each type of clock on board, a rubidium and a hydrogen maser clock. The frequency is at around 6 GHz for the rubidium clock and at around 1.4 GHz for the hydrogen clock. The Galileo system uses the clock frequency as a very stable reference by which other units can generate the accurate signals that the Galileo satellites will broadcast. The broadcast signals will also provide a reference by which the less stable user receiver clocks can continuously reset their time.
-Highly accurate atomic clocks are installed on these satellites. Each of the 30 satellites in the Galileo system will have two of each type of clock on board, a rubidium and a hydrogen maser clock. The frequency is at around 6 GHz for the rubidium clock and at around 1.4 GHz for the hydrogen clock. The Galileo system uses the clock frequency as a very stable reference by which other units can generate the accurate signals that the Galileo satellites will broadcast. The broadcast signals will also provide a reference by which the less stable user receiver clocks can continuously reset their time.
+The satellites are deployed gradually according to the [[GALILEO_Future_and_Evolutions|Galileo Program schedule]].
 ==GALILEO Ground Segment==
+The [[GALILEO Ground Segment|Galileo Ground Segment]]  is the responsible for the proper operation of the GNSS system. Its basic functions are:
-[[File:Galileo Ground Segment.png|300px|Galileo Ground Segment|thumb]]The [[GALILEO Ground Segment|Galileo Control Segment]] (also referred to as Ground Segment) is the responsible for the proper operation of the GNSS system. Its basic functions are:
 * To control and maintain the status and configuration of the satellite constellation.
 * To predict ephemeris and satellite clock evolution.
@@ Line 47: / Line 40: @@
 * To update the navigation messages for all the satellites.
-The [[GALILEO Ground Segment|Galileo Ground Segment]] constitutes the major system element controlling the entire constellation, the navigation system facilities and the dissemination services. It is composed of two Ground Control Centres (GCC), five Telemetry, Tracking and Control (TT&C) stations, nine Mission Uplink Stations (ULS), and about thirty Galileo Sensor Stations (GSS). The Ground Control Segment (GCS) as the responsible for satellite constellation control and management of Galileo satellites, it provides the telemetry, telecommand and control function for the whole Galileo satellite constellation. Its functional elements are deployed within the GCCs and the five globally distributed TT&C stations.
+The [[GALILEO Ground Segment|Galileo Ground Segment]] constitutes the major system element controlling the entire constellation, the navigation system facilities and the dissemination services. It is composed of two Ground Control Centers (GCC), five Telemetry, Tracking and Control (TT&C) stations, nine Mission Uplink Stations (ULS), a global network of Galileo Sensor Stations (GSS)<ref>Official Journal of the European Union of 23 of February 2012 (2012/117/EU), [http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2012:052:0028:0031:EN:PDF Annex 1]</ref> and the European [[GNSS Service Centre]] (GSC)<ref>http://www.gsc-europa.eu/</ref>.
+The Galileo Ground Segment is decomposed into the Galileo Control System and the Galileo Mission System. The Galileo Control System (GCS), as the responsible for satellite constellation control and management of Galileo satellites, provides the telemetry, telecommand and control function for the whole Galileo satellite constellation. The Galileo Mission System (GMS) is responsible for the determination and uplink of navigation and integrity data messages needed to provide the navigation and UTC time transfer service.
 ==GALILEO User Segment==
 The  [[GALILEO User Segment|Galileo User Segment]] is composed by [[GALILEO Receivers|Galileo receivers]]. Their main function is to receive Galileo signals, determine pseudoranges (and other observables), and solve the navigation equations in order to obtain their coordinates and provide a very accurate time.
 Three receiver development activities have been initiated within the Galileo programme, addressing the different needs of the system development process and covering the range of signals and services that will be offered. Activities in receiver development are in the following areas:<ref name="EsaGalileoweb"/>
+# test user segment;
-*test user segment
+# receivers for the signals transmitted by the first experimental satellites;
-*receivers for the signals transmitted by the first, experimental satellites
+# receivers for the Galileo receiver chain.
-*receivers for the Galileo receiver chain
 ==Notes==
@@ Line 65: / Line 59: @@
 [[Category:GALILEO|Architecture]]
+[[Category:GALILEO Architecture]]
+[[Category:GALILEO Ground Segment]]