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{{Article Infobox2
{{Article Infobox2
|Category=GALILEO
|Category=GALILEO
|Title={{PAGENAME}}
|Editors=GMV
|Authors=GMV
|Level=Basic
|Level=Basic
|YearOfPublication=2011
|YearOfPublication=2011
|Logo=GMV
|Logo=GMV
|Title={{PAGENAME}}
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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 Architecture|Galileo Global Component]] will also include a set of Test 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 a very accurate time.  
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 receiver are an antenna with pre-amplification, a 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 satellites.  


Any navigation solution provided by a [[:Category:Receivers|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>
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.


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>
==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.  


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. They are stored on board each satellite with a validity duration and broadcast world-wide by all the satellites of the Galileo constellation. The 4 types of data needed to perform positioning:<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>
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>


*Ephemeris which are needed to indicate the position of the satellite to the user receiver
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>
*Time and clock correction parameters which are needed to compute pseudo-range
# Ephemeris which are needed to compute the position of the satellite to the user receiver.
*Service parameters which are needed to identify the set of navigation data, satellites, and indicators of the signal health
# Time and clock correction parameters which are needed to compute satellite clock offsets and time conversions.
*Almanac which are needed to indicate the position of all the satellites in the constellation with a reduced accuracy
# Service parameters with satellites health.
*Ionospheric parameters model needed for single frequency receivers
# 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


The GALILEO Signal In Space<ref name="SIS_ICD"/> data channels transmit different message types according to the general contents: The F/NAV types of message correspond to the [[GALILEO Open Service| Galileo Open Service]] (OS), the I/NAV types of message correspond to the [[GALILEO Open Service| Galileo Safety-of-Life Service]] (SoL), and the C/NAV message format to [[GALILEO Comercial Service|Galileo Comercial Service]] (CS).
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 <ref name = "Use Galileo">[https://www.usegalileo.eu/EN/ UseGalileo.eu website]</ref>.


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.
==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 <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>:
Activities in receiver development are in the following areas:
[[File:Galileo_User_Segment_GSC.png|300px|Overall context of the GSC|thumb]]
*test user segment
The GSC functionality and services when fully developed will cover the followings<ref name = "Galileo-OS-SDD"></ref>:
*receivers for the signals transmitted by the first, experimental satellites
*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.
*receivers for the Galileo receiver chain
*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.  
The ephemeris and clocks parameters are usually updated every two hours, while the almanac is updated at least every six days.
*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)
The GALILEO Signal In Space is specified in the following documents:<ref>[http://www.gps.gov/technical/icwg/ GPS Interface Control Documents]</ref>
*IS-GPS-200E: Interface between the space segment of the Global Positioning System and the navigation user segment of the GPS for radio frequency link 1 (L1) and link 2 (L2)
*IS-GPS-705A: interface between the space segment of the Global Positioning System and the navigation user segment of the GPS for radio frequency link 5 (L5).
 
Receivers can be categorized by their type in different ways, and under different criteria. For instance, receivers can be stand-alone, or may benefit from corrections or measurements provided by augmentation system or by receivers in the vicinities (DGPS).
Moreover receivers might be generic all purpose receivers or can be built specifically having the application in mind:<ref name="GPS_APP">[http://en.wikipedia.org/wiki/GNSS_applications GNSS applications on Wikipedia]</ref> navigation, accurate positioning or timing, surveying, etc.
In addition to position and velocity, GPS receivers also provide time. An important amount of economic activities, such wireless telephone, electrical power grids or financial networks rely on precision timing for synchronization and operational efficiency. GPS enables the users to determine the time with a high precision without needing to use expensive atomic clocks.
 
==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 open, commercial and safety-of-life services
*a test user receiver for the public, regulated service
*search and rescue 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.


==Applications==
==Applications==
[[GNSS Applications General Introduction|GPS applications]] are all those applications that use GPS to collect position, velocity and time information to be used by the application.
The European Commission is committed to 6 priority domains identified in the impact assessment accompanying its Action Plan on  [[GNSS Applications|GNSS Applications]]:<ref>[http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=SEC:2010:0716:FIN:EN:PDF Impact Assesment: Action Plan on Global Navigation Satellite System (GNSS) Applications]</ref>  
For instance, the position and velocity provided by GPS may be used for [[Civil Applications|civil applications]] such as:<ref>[http://www.gps.gov/applications GPS applications on gps.gov]</ref>  
* applications for individual handsets and mobile phones (LBS);
*'''Agriculture''': GPS-based applications in precision farming are being used for farm planning, field mapping, soil sampling, tractor guidance, crop scouting, variable rate applications, and yield mapping.
* road transport;
*'''Aviation Applications''': GPS provides position determination for all phases of flight from departure, en route, and arrival, to airport surface navigation.
* aviation;
*'''Rail Applications''': Rail system use the GPS in combination with other sensors to maintain smooth flow of traffic, prevent collisions by precise knowledge of where a train is located, increase efficiency and capacity, etc.
* maritime transport;
*'''Road Applications''': GPS may be used to provide in-vehicle navigation, fleet management, tolling applications, etc.
* precision agriculture and environment protection;
*'''Surveying and mapping''': The main limitation of the traditional surveying techniques is the requirement for a line of sight between surveying points. Using the accurate position provided by GPS surveying and mapping results can be obtained faster and with a lower cost.
* 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==
<references/>
<references/>


[[Category:GALILEO]]
[[Category:GALILEO]]
[[Category:GALILEO Architecture]]
[[Category:GALILEO User Segment]]

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].

  • App transport.png
  • App agriculture.png
  • App survey.jpg

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
Retrieved from "https://gssc.esa.int/navipedia/index.php?title=Galileo_User_Segment&oldid=14517"