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m (moved GALILEO User Segment to Galileo User Segment: Galileo is a name and not an acronym.)
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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 General Introduction|Galileo]] System is an independent, global, European-controlled, satellite-based navigation system and provides a number of guaranteed services to users equipped with Galileo-compatible receivers.  


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 User Segment consists in the user receivers; their main function is to receive Galileo signals, determine pseudoranges (and other observables), and [[An intuitive approach to the GNSS positioning|solve the navigation equations]] in order to obtain their coordinates and provide accurate time synchronization.  
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 User Segment is composed by all the compatible receivers and devices which collect the Galileo signals, determine pseudoranges (and other observables), and [[An intuitive approach to the GNSS positioning|solve the navigation equations]] in order to obtain their coordinates and provide accurate time synchronization. There are different user’s communities depending on the application and covering a wide range, from transport to timing applications.


Basic elements of a generic [[GNSS Receivers General Introduction|GNSS Receiver]] are an antenna with pre-amplification, an L-band radio frequency section, a microprocessor, an intermediate-precision oscillator, a feeding source, some memory for data storage, and an interface with the user. The calculated position is referred to the antenna phase centre.
Basic elements of a generic [[GNSS Receivers General Introduction|GNSS Receiver]] are an antenna with pre-amplification, an L-band radio frequency section, a microprocessor, an intermediate-precision oscillator, a feeding source, some memory for data storage, and an interface with the user. The calculated position is referred to the antenna phase centre.


==GALILEO Receivers==
==Galileo Receivers==
A [[GALILEO Receivers|GALILEO Receiver]] is a device capable of determining the user position, velocity and precise time (PVT) by processing the signal broadcasted by Galileo satellites.  
A [[GALILEO Receivers|Galileo Receiver]] is a device capable of determining the user position, velocity and precise time (PVT) by processing the signal broadcasted by Galileo satellites.  


Any [[An intuitive approach to the GNSS positioning|navigation solution]] provided by a [[GNSS Receivers General Introduction|GNSS Receiver]] is based on the computation of its distance to a set of satellites, by means of extracting the propagation time of the incoming signals traveling through space at the speed of light, according to the satellite and receiver local clocks. Notice that satellites are always in motion, so previous to obtaining the navigation message, the satellite’s signal is detected and tracked. The receiver’s functional blocks that perform these tasks are the antenna, the front-end and the baseband signal processing (in charge of acquiring and tracking the signal).<ref name="GNSS-Book ">J. Sanz Subirana, JM. Juan Zornoza and M. Hernández-Pajares, ''Global Navigation Satellite Systems: Volume I: Fundamentals and Algorithms''</ref>
Any [[An intuitive approach to the GNSS positioning|navigation solution]] provided by a [[GNSS Receivers General Introduction|GNSS Receiver]] is based on the computation of its distance to a set of satellites, by means of extracting the propagation time of the incoming signals traveling through space at the speed of light, according to the satellite and receiver local clocks. Notice that satellites are always in motion, so previous to obtaining the navigation message, the satellite’s signal is detected and tracked. The receiver’s functional blocks that perform these tasks are the antenna, the front-end and the baseband signal processing (in charge of acquiring and tracking the signal).<ref name="GNSS-Book ">J. Sanz Subirana, JM. Juan Zornoza and M. Hernández-Pajares, ''Global Navigation Satellite Systems: Volume I: Fundamentals and Algorithms''</ref>


Once the signal is acquired and tracked, the receiver application decodes the navigation message. The navigation data contain all the parameters that enable the user to perform positioning service. The four types of data needed to perform positioning are:<ref name="SIS_ICD">[http://ec.europa.eu/enterprise/policies/satnav/galileo/files/galileo-os-sis-icd-issue1-revision1_en.pdf Galileo OS SIS ICD Issue 1 Revision 1 September 2010e]</ref>
Once the signal is acquired and tracked, the receiver application decodes the navigation message. The navigation data contain all the parameters that enable the user to perform positioning service. The types of data needed to perform positioning are:<ref name = "Galileo-OS-SDD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SDD.pdf Applicable Galileo Open Service –Service Definition Document]</ref>
# Ephemeris which are needed to indicate the position of the satellite to the user receiver.
# Ephemeris which are needed to compute the position of the satellite to the user receiver.
# Time and clock correction parameters which are needed to compute pseudo-range.
# Time and clock correction parameters which are needed to compute satellite clock offsets and time conversions.
# Service parameters which are needed to identify the set of navigation data, satellites, and indicators of the signal health.
# Service parameters with satellites health.
# Almanac which are used to compute the position of all the satellites in the constellation with a reduced accuracy, so that the receivers improve the time needed for the initial satellite tracking process.
# The ionospheric parameters model, needed for single-frequency users.
# Almanac which allow less precise computation of the position of all the satellites in the constellation to facilitate the initial acquisition of the signals by the receiver


For single frequency receivers, the Broadcast Group Delays and Ionospheric parameters are also needed.
For single frequency receivers, the Broadcast Group Delays are also needed.
 
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:
* test user segment;
* receivers for the signals transmitted by the first, experimental satellites;
* receivers for the Galileo receiver chain.
 
The Galileo global navigation satellite system will employ many new methods and technologies to offer superior performance and reliability. Development of the advanced receivers required to make use of the system is continuing.<ref name="EsaGalileoweb">[http://www.esa.int/esaNA/galileo.html ESA Galileo web page]</ref>
 
==Test user segment==
The test user segment is being used for system validation and signal experimentation. Two parallel developments have been performed, with the aim of securing equipment availability and achieving the highest confidence in the results. The test user segment consists of:<ref name="EsaGalileoweb"/>
* a test user receiver for the [[Galileo Open Service (OS)|Open Service]] and [[Galileo Commercial Service (CS)|Commercial Service]];
* a test user receiver for the [[Galileo Public Regulated Service (PRS)|Public Regulated Service (PRS)]];
* [[Galileo Search and Rescue Service |Search and Rescue (SAR)]] test beacon equipment;
* test support tools, such as a simulator for the satellite constellation.
 
The receivers are based on a highly flexible software-defined concept implementing 14 different receiver configurations. They are able to emulate different receiver classes and provide a variety of internal measurements when combined with an analysis sub-system running on an attached laptop computer.
 
The objectives of the initial part of the design phase for the test user segment have been fully achieved. A prototype receiver has been constructed, which is capable of receiving all Galileo signal components on all carriers defined in the current specification. The feasibility of acquiring and tracking the new Galileo signals has been proven.


In 2010 there were only three chipset manufacturers producing Galileo-ready products. Since them, the market has been evolving, and today it is ready for Galileo. The list of Galileo compatible devices that are available today can be found at the following reference <ref name = "Use Galileo">[https://www.usegalileo.eu/EN/ UseGalileo.eu website]</ref>.


==Service Centers==
==Service Centers==
The [[GNSS Service Centre]] aim at interfacing to users by providing added value services.
The European [[GNSS Service Centre]] (GSC) aims at providing a single interface between the Galileo system and the Galileo Open Service (OS) and High Accuracy Service (HAS) users for the provision of specific services beyond the signal in space transmitted by the satellites. The GSC assures knowledge sharing, custom performance assessment, dissemination of information and support to the provision of value-added services which are enabled by the Galileo OS and HAS core services <ref name = "Galileo-OS-SDD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SDD.pdf Applicable Galileo Open Service –Service Definition Document]</ref>:
Where appropriate for the different positioning, timing and navigation service categories, these centres perform functions such as providing<ref>[http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&ved=0CDIQFjAB&url=http%3A%2F%2Fesamultimedia.esa.int%2Fconferences%2F01C14%2Fpapers%2F3.1.doc&ei=Jx0IUbPoM8vhtQaIqID4BA&usg=AFQjCNE29t5mj4nDY5Z_WSjYjCrXGpjgVw GALILEO System Architecture and Services, ESA, EC]</ref>:  
[[File:Galileo_User_Segment_GSC.png|300px|Overall context of the GSC|thumb]]
 
The GSC functionality and services when fully developed will cover the followings<ref name = "Galileo-OS-SDD"></ref>:  
*Information and warranty on performances and data archiving;
*Helpdesk support which is intended to answer questions from OS users on Galileo OS SIS, GSC OS Support Services and from OS receiver and developers of applications.
*Subscription and access key management;
*Information regarding the Galileo system status (Galileo Almanacs and ephemeris, constellation status and provision of Galileo Service Notices)
*Insurance, liability; legal and litigation management;
*Notifications to users’ publication which includes general information on the constellation and space vehicle status (published by means of Notice Advisory to Galileo Users messages – NAGUs) and also reports related to Galileo Open Service navigation performance indicators and the GSC performances.
*Certification and license information management;
*Programme Reference documentation and general information included in an Electronic Library.
*Commercial interfaces;
*Interface with GNSS Service providers.
*Support to application development and possible elaboration of R&D approaches.
*Support on topics like GNSS Simulation and Testing Infrastructure (GSTI) for the GNSS developers.
*The user satisfaction monitoring regarding Galileo (meaning customised performance assessments, reporting for specific communities and support regarding Galileo services development for different communities and domains)


==Applications==
==Applications==
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* precision agriculture and environment protection;  
* precision agriculture and environment protection;  
* civil protection and surveillance.
* civil protection and surveillance.
 
Examples of applications in which Galileo can play a role are detailed in Galileo GSC [https://www.gsc-europa.eu/galileo-gsc-overview/applications website] and devices that implement Galileo can be found on the ”Use Galileo” website from the [https://www.gsc-europa.eu/galileo-gsc-overview/applications GSA]<ref name = "Use Galileo">[https://www.usegalileo.eu/EN/ UseGalileo.eu website]</ref>.


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==Notes==
==Credits==
The information provided in this article has been compiled by GMV. In some cases, tables and paragraphs have been extracted from the indicated references, in particular from the ''European GNSS Service Centre (GSC)'' [https://www.gsc-europa.eu/ website].
<references group="footnotes"/>
<references group="footnotes"/>
==References==
==References==

Latest revision as of 15:20, 2 April 2019


GALILEOGALILEO
Title Galileo User Segment
Edited by GMV
Level Basic
Year of Publication 2011
Logo GMV.png

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

The Galileo system is divided into three major segments: Space Segment, Ground Segment and User Segment. The Galileo User Segment is composed by all the compatible receivers and devices which collect the Galileo signals, determine pseudoranges (and other observables), and solve the navigation equations in order to obtain their coordinates and provide accurate time synchronization. There are different user’s communities depending on the application and covering a wide range, from transport to timing applications.

Basic elements of a generic GNSS Receiver are an antenna with pre-amplification, an L-band radio frequency section, a microprocessor, an intermediate-precision oscillator, a feeding source, some memory for data storage, and an interface with the user. The calculated position is referred to the antenna phase centre.

Galileo Receivers

A Galileo Receiver is a device capable of determining the user position, velocity and precise time (PVT) by processing the signal broadcasted by Galileo satellites.

Any navigation solution provided by a GNSS Receiver is based on the computation of its distance to a set of satellites, by means of extracting the propagation time of the incoming signals traveling through space at the speed of light, according to the satellite and receiver local clocks. Notice that satellites are always in motion, so previous to obtaining the navigation message, the satellite’s signal is detected and tracked. The receiver’s functional blocks that perform these tasks are the antenna, the front-end and the baseband signal processing (in charge of acquiring and tracking the signal).[1]

Once the signal is acquired and tracked, the receiver application decodes the navigation message. The navigation data contain all the parameters that enable the user to perform positioning service. The types of data needed to perform positioning are:[2]

  1. Ephemeris which are needed to compute the position of the satellite to the user receiver.
  2. Time and clock correction parameters which are needed to compute satellite clock offsets and time conversions.
  3. Service parameters with satellites health.
  4. The ionospheric parameters model, needed for single-frequency users.
  5. Almanac which allow less precise computation of the position of all the satellites in the constellation to facilitate the initial acquisition of the signals by the receiver

For single frequency receivers, the Broadcast Group Delays are also needed.

In 2010 there were only three chipset manufacturers producing Galileo-ready products. Since them, the market has been evolving, and today it is ready for Galileo. The list of Galileo compatible devices that are available today can be found at the following reference [3].

Service Centers

The European GNSS Service Centre (GSC) aims at providing a single interface between the Galileo system and the Galileo Open Service (OS) and High Accuracy Service (HAS) users for the provision of specific services beyond the signal in space transmitted by the satellites. The GSC assures knowledge sharing, custom performance assessment, dissemination of information and support to the provision of value-added services which are enabled by the Galileo OS and HAS core services [2]:

Overall context of the GSC

The GSC functionality and services when fully developed will cover the followings[2]:

  • Helpdesk support which is intended to answer questions from OS users on Galileo OS SIS, GSC OS Support Services and from OS receiver and developers of applications.
  • Information regarding the Galileo system status (Galileo Almanacs and ephemeris, constellation status and provision of Galileo Service Notices)
  • Notifications to users’ publication which includes general information on the constellation and space vehicle status (published by means of Notice Advisory to Galileo Users messages – NAGUs) and also reports related to Galileo Open Service navigation performance indicators and the GSC performances.
  • Programme Reference documentation and general information included in an Electronic Library.
  • Interface with GNSS Service providers.
  • Support on topics like GNSS Simulation and Testing Infrastructure (GSTI) for the GNSS developers.
  • The user satisfaction monitoring regarding Galileo (meaning customised performance assessments, reporting for specific communities and support regarding Galileo services development for different communities and domains)

Applications

The European Commission is committed to 6 priority domains identified in the impact assessment accompanying its Action Plan on GNSS Applications:[4]

  • applications for individual handsets and mobile phones (LBS);
  • road transport;
  • aviation;
  • maritime transport;
  • precision agriculture and environment protection;
  • civil protection and surveillance.

Examples of applications in which Galileo can play a role are detailed in Galileo GSC website and devices that implement Galileo can be found on the ”Use Galileo” website from the GSA[3].

Credits

The information provided in this article has been compiled by GMV. In some cases, tables and paragraphs have been extracted from the indicated references, in particular from the European GNSS Service Centre (GSC) website.

References

  1. ^ J. Sanz Subirana, JM. Juan Zornoza and M. Hernández-Pajares, Global Navigation Satellite Systems: Volume I: Fundamentals and Algorithms
  2. ^ a b c Applicable Galileo Open Service –Service Definition Document
  3. ^ a b UseGalileo.eu website
  4. ^ Impact Assesment: Action Plan on Global Navigation Satellite System (GNSS) Applications