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Galileo Future and Evolutions

2025-07-28T16:24:09Z

Vicente.Navarro: Reverted edits by Gssctest (talk) to last revision by Gema.Cueto

{{Article Infobox2
|Category=GALILEO
|Editors=GMV
|Level=Basic
|YearOfPublication=2011
|Logo=GMV
|Title={{PAGENAME}}
}}
The Galileo program is Europe's initiative for a state-of-the-art global satellite navigation system, providing a highly accurate, guaranteed global positioning service under civilian control.<ref name="CR Galileo">Council Resolution of 19 July 1999 on the involvement of Europe in a new generation of satellite navigation services -Galileo- Definition phase [http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:C:1999:221:0001:0003:EN:PDF (1999/C 221/01)]</ref> While providing autonomous navigation and positioning services, the system established under the Galileo program is at the same time interoperable with other GNSS systems (such as [[GPS General Introduction|GPS]], [[GLONASS General Introduction|GLONASS]] or [[BeiDou General Introduction|BEIDOU]]). The system, once fully deployed, will consist of 31 satellites, to be deployed in a staggered approach, and the associated ground infrastructure.<ref>[http://www.esa.int/esaNA/galileo.html ESA Galileo web page]</ref>

==Galileo phases==
The Galileo program has been structured according to three main phases:<ref name="EC GAL web">[http://ec.europa.eu/growth/sectors/space/galileo_en European Commision Galileo website]</ref><ref name="Mid-term review">[http://europa.eu/rapid/press-release_MEMO-11-26_en.htm Mid-term review of the European satellite radio navigation programmes]</ref>
# In-Orbit Validation (IOV) phase:
#:The IOV phase consisted of qualifying the system through tests and the operation of two experimental satellites and a reduced constellation of four operational satellites and their related ground infrastructure.
#:The two experimental satellites were launched in respectively December 2005 and April 2008. Their purpose was to characterize the Medium-Earth Orbit (MEO) environment (radiations, magnetic field etc) and to test in such environment the performance of critical payload technology (atomic clocks and radiation hardened digital technology). They also provided an early experimental signal-in-space allowing securing the frequency spectrum required for Galileo in accordance with WRC RNSS allocations. The first 2 Galileo operational satellites were launched by ESA with the Soyuz VS01 flight on 21st October 2011 and were declared fully operational since April 2012. The next two Galileo satellites, completing the IOV quartet, were launched on 12th October 2012 by the Soyuz ST-B launcher from the Guiana Space Centre (please refer to [http://www.esa.int ESA website] for videos on the launches) and they are transmitting signals on E1, E5 and E6 band since December 2012. More information on the Galileo IOV Satellites can be found [[Galileo_IOV_Satellites|here]]. The [http://www.esa.int/Our_Activities/Navigation/Galileo_fixes_Europe_s_position_in_history first position fix] using the IOV satellite quartet, was reported on the 12th of March 2013 by ESA's navigation laboratory in the Netherlands. After that ESA started a wide variety of IOV tests all across Europe to assess the performance of the system sub-set already deployed. As of February 2014 Galileo achieved In-Orbit Validation since the results of the tests shown that "Galileo works, and it works well". The performance to be achieved will effectively be reached as more satellites are launched and ground stations come on line.<ref>[http://gpsworld.com/galileo-achieves-in-orbit-validation/ Galileo Achieves In-Orbit Validation], GPS World, GPS World Staff, February 2014</ref><ref>[http://www.esa.int/Our_Activities/Navigation/Galileo_works_and_works_well Galileo Works, And Works Well], ESA, February 2014</ref>
# Initial Operational Capability (IOC) phase:
#:The IOC stage represents the partial commissioning of the ground and space infrastructure as from 2014-2015 and the provision of the [[GALILEO Open Service|Open Service]], the [[GALILEO Search and Rescue Service|Search And Rescue service]] and the [[GALILEO Public Regulated Service|PRS]].The provision of these Galileo Initial Services was declared in December 2016.<ref name ="goes live">[http://europa.eu/rapid/press-release_IP-16-4366_en.htm Galileo goes live!]</ref> The procurement of the IOC phase included the first batch of satellites (14 additional satellites to the 4 IOV satellites), the launch services, the needed mission and control ground infrastructure, the system support services and the corresponding operations<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>. Details on the different steps of this phase are presented in [[#Galileo Deployment | Galileo Deployment]]
# Full Operational Capability (FOC) phase:
#:The FOC phase consists of the deployment of the full system which will consist of 30 satellites, control centres located in Europe and a network of sensor stations and uplink stations installed around the globe. Galileo's Full Operational Capability (FOC) is expected for 2020, in a staggered approach from the IOC phase. Four new Galileo satellites were put on orbit on top of an Ariane 5, on July 25, 2018 from the European spaceport in Kourou, French Guiana. This launch brings the Galileo constellation finalization, with all objectives achieved: Galileo signal is better than expected and now usable in all new mobile phones.

The list of past and present satellites of the Galileo navigation system, as well as the following satellite launches, can be consulted in<ref name="Galileo FOC">[https://en.wikipedia.org/wiki/List_of_Galileo_satellites Galileo FOC]</ref>

The definition phase and the development and In-Orbit Validation phase of the Galileo program was carried out by the [http://www.esa.int/ European Space Agency (ESA)] and co-funded by ESA and the [http://europa.eu/ European Union]. The Full Operational Capability phase of the Galileo program is fully funded by the European Union and managed by the [http://ec.europa.eu/index_en.htm European Commission]. The Commission and ESA signed a delegation agreement by which ESA acts as design and procurement agent on behalf of the Commission.

== Galileo Deployment ==

Galileo’s seventh and eighth satellites launched successfully in March 2015. The European Space Agency (ESA) planned four more satellites to reach orbit in that year, and space maneuvers for Galileo 5 and 6 were completed, with a recovery plan currently under study.
Both satellites 7 and 8 started transmitting signals in May 2015, with the first E1 and E5 signals from Galileo 8 received on May 21 and the first E1 and E5 signals from Galileo 7 on May 25.<ref>[http://gpsworld.com/newest-galileo-satellites-now-transmitting/ Both New Galileo Satellites Now Transmitting]</ref><br>
A further two Galileo satellites were successfully launched on September 11, 2015, raising the total number of satellites in the constellation to 10. <ref>[http://insidegnss.com/esa-launches-two-galileo-satellites/ ESA Launches Two Galileo Satellites]</ref>
Several stations participating in the International GNSS Service Multi-GNSS Experiment started tracking the new satellites on October 12th, 2015. <ref>[http://gpsworld.com/newest-gnss-satellites-being-tracked/ Newest GNSS Satellites Being Tracked]</ref><br>
The 11th and 12th Galileo satellites were launched on December 17, 2015 <ref>[http://insidegnss.com/galileo-program-adds-pair-of-satellites-to-constellation/ Galileo Program Adds Pair of Satellites to Constellation]</ref> and became operational in the end of April 2016 <ref>[http://insidegnss.com/two-more-galileo-satellites-set-healthy/ Two More Galileo Satellites Set Healthy]</ref>.<br>
The total number of satellites in the constellation was increased to 14 on May 24, 2016, with the launch of two additional satellites from the French Guiana <ref>[http://insidegnss.com/successful-launch-continues-build-out-of-galileo-constellation/ Successful Launch Continues Build-Out of Galileo Constellation]</ref>

On November 17th, 2016, the Galileo constellation was reinforced with another 4 satellites. <ref>[http://gpsworld.com/the-launch-of-4-and-declaration-of-galileo-operations/ The launch of 4 and declaration of Galileo operations]</ref>

With this last launch, Galileo became operational for initial services on December 15th, 2016. <ref name ="goes live">[http://europa.eu/rapid/press-release_IP-16-4366_en.htm Galileo goes live!]</ref>. Four new Galileo satellites were successfully launched on December 12th, 2017. This last launch brings the Galileo constellation to a total of 22 satellites.

On April 2017, the Galileo Search And Rescue (SAR) service was officially launched. This new service reduces the detection delay of a distress signal from up to several hours to 10 minutes. The a return link, a signal informing the person in distress that the signal has been received and localized, was declared in January 2020.<ref>[https://www.gsa.europa.eu/newsroom/news/galileo-return-link-service-declared-european-space-conference Galileo Return Link Service declaration]</ref>

[[Galileo Open Service Navigation Message Authentication | Galileo OS-NMA]] capability is gradually being added to Galileo Open Service in the short term. It is a data authentication function for the Galileo Open Service worldwide users, freely accessible to all. OSNMA provides receivers with the assurance that the received Galileo navigation message is coming from the system itself and has not been modified.

OSNMA is authenticating data for geolocation information from the Open Service through the Navigation Message (I/NAV) broadcast on the E1-B signal component. This is realised by transmitting authentication-specific data in previously reserved fields of the E1 I/NAV message. By using these fields, OSNMA does not introduce any overhead to the system, thus the OS navigation performance remains untouched<ref name="OS-NMA">[https://www.gsc-europa.eu/galileo/services/galileo-open-service-navigation-message-authentication-osnma Galileo OS-NMA Roadmap]</ref>.
[[File:OSNMA_Roadmap.png|450px|center|Galileo OSNMA Roadmap|thumb]]
Also, [https://www.euspa.europa.eu/newsroom-events/news/implementation-quasi-pilot-g2g-signals| G2G is developing dedicated quasi-pilot signals], for easing the acquisition process at the receiver level, would further support these developments in user technology to reduce the power consumption in the processes of signal acquisition for a faster first fix. This is a real differentiator of Galileo that would significantly reduce the time of acquisition of the Galileo signals, in single and multifrequency scenarios. This is relevant for different Galileo use cases and applications where a requirement at the receiver level is to minimize the energy spent on signal acquisition for the first position fix.

The G2G system and technological development are being supported through ESA's HSNAV GNSS and H2020 Programmes, delegating their technical definition and the management of their activities related to their implementation, guaranteeing compatibility with previous versions, the continuity of Galileo services and their possible integration with Augmentation Systems (SBAS), in the European case, is the EGNOS system, which consists of three additional satellites.

Regarding [[Galileo High Accuracy Service (HAS) | Galileo High Accuracy]], this service will be implemented in a three-step approach<ref name="HAS_note">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_HAS_Info_Note.pdf Galileo High Accuracy Service, Info Note]</ref><ref name="HAS_GSC">[https://www.gsc-europa.eu/galileo/services/galileo-high-accuracy-service-has Galileo HAS in GSC website]</ref>:
*Phase 0 (HA testing and experimentation), starting in Q2 2021 focusing on activities aimed at validating Galileo’s dissemination capabilities through the E6B channel and performing initial high-accuracy testing. Internal testing is ongoing since 2019.
*Phase 1 (HA Initial Service) from 2022. Provision of an initial Galileo High Accuracy Service resulting from the implementation of a high-accuracy data generation system processing Galileo system data only. The HA initial service will deliver Service Level 1 only with a reduced performance (below the full service’s targets).
*Phase 2 (HA Full Service). Full provision of the Galileo High Accuracy Service starting from 2023, including Service Level 1 and Service Level 2, fulfilling its target performance (e.g. 20 cm positioning performance).

==Galileo Evolutions==
[[File:Galileo_clock.jpg‎‎|300px|Galileo Clock (artistic interpretation)|thumb]]
The European Parliament and the Council allocated the management of the Galileo programme to the European Commission.<ref>[http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:196:0001:0011:en:PDF Regulation (EC) No 683/2008 of the European Parliament and of the Council of 9 July 2008 on the further implementation of the European satellite navigation programmes (EGNOS and Galileo)]</ref>
The European Commission set up a consultative group of GNSS experts called the Mission Evolution Advisory Group (MEAG). MEAG aims at providing EC with independent advice and ''recommendations on potential evolutions of the mission objectives and the service definitions for the European satellite navigation programmes Galileo and EGNOS''.

In April 2013, the member states' Permanent Representatives (Coreper) endorsed the compromise reached between the Council and the European Parliament in their negotiations on a new financial and governance framework for the European satellite navigation systems (EGNOS and Galileo) for the period covered by the multi-annual financial framework for 2014-2020<ref name="EUpress">[http://www.consilium.europa.eu/uedocs/cms_data/docs/pressdata/en/trans/136813.pdf "Council and European Parliament reach agreement on financing and governance of the European satellite navigation systems]</ref>.

The draft regulation contains the following key elements based on a first proposal presented by the Commission in December 2011, excluding the financial envelope<ref name="EUpress"/>:
*A tentative budget of EUR 6.3 billion (at constant 2011 prices), to be fully financed from the EU budget.
*A definition of the EU satellite navigation systems and Programmes and of the services they will provide;
*A new governance framework that establishes a strict division of tasks between the Commission, the European GNSS Agency and the European Space Agency;
*Rules on public procurement, promoting the widest participation possible throughout the Union and ensuring fair competition conditions.

The Galileo Evolutions are currently under technical study within the European GNSS Evolution Programme
(EGEP),<ref name="EGEP">[http://www.esa.int/SPECIALS/GNSS_Evolution/index.html European GNSS Evolution Programme website]</ref> an ESA optional programme supported by 17 Member States and Canada. Its primary aim is to undertake research and development in verification of technologies relating to regional space-based augmentation systems (SBAS) and global navigation satellite systems (GNSS).
Regarding Galileo, EGEP objectives are:
* define future system architectures for Galileo and prepare the technology for future versions of the system;
* provide testbeds and system tools;
* improve Agency knowledge of GNSS performance monitoring and the principal environmental factors influencing performance;
* promote and support scientific exploitation of Galileo.

Another main objective of the EGEP is the preparation of the future generation of Galileo (Galileo Second Generation, G2G), Galileo Second Generation teams are hard at work building twelve satellites that will integrate seamlessly with the current Galileo navigation fleet. With two families of six satellites, developed by Thales Alenia Space (TAS) and Airbus Defence and Space (ADS), the upgraded models will bring countless benefits to users in Europe and around the world. But before they are ready for launch, each satellite must undergo rigorous testing on the ground.

A crucial phase in the development of a new satellite is the System Compatibility Test Campaign (SCTC), a comprehensive round of tests to ensure their full compatibility with ground segment. For the G2 programme, the ground segment is being developed by Thales Alenia Space, GMV, Thales SIX GTS and their industrial partners. The SCTC is divided into multiple phases, with each test case gradually increasing in complexity.<ref name="Galileo 2G">[https://www.esa.int/Applications/Satellite_navigation/Galileo/Galileo_Second_Generation_developing_at_full_speed Galileo Second Generation]</ref>

The Galileo Second Generation (G2G) is expected to deliver improved performance and RNP (Required Navigation Performances) features such as reliability, maintainability, availability, continuity, accuracy and integrity. This is why the European Commission (EC) has decided to launch a Transition Programme with ESA for technical definition and implementation.

The constant need for orbital spare parts to replace end-of-life GALILEO satellites must be taken into account, which will ensure that the European system continues to operate without losing the availability of services. In 2017, twelve additional satellites were requested from the industry to serve as a transition to a future generation, with the objective of maintaining and improving the precision, robustness, availability and integrity performance in its main PNT (Positioning, Navigation and Time) function, as a permanent part of the European and global landscape in the Global Navigation Satellite System (GNSS) and to confer European autonomy over its constellation, for civil use and with governmental applications.

==Notes==
<references group="footnotes"/>
==References==
<references/>

[[Category:GALILEO|Future]]
[[Category:GALILEO Future and Evolutions]]

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2025-07-14T13:21:18Z

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NTCM G Ionospheric Model

2025-07-14T12:13:45Z

Vicente.Navarro:

{{Article Infobox2
|Category=Fundamentals
|Authors=
|Level=Intermediate
|YearOfPublication=2025
|Title={{PAGENAME}}
}}
__TOC__
The '''NTCM G''' (Neustrelitz Total Electron Content Model) ionospheric model is designed to compute ionospheric corrections based on the broadcast coefficients in the navigation message for Galileo single-frequency users. NTCM-G is proposed as an alternative to the [[NeQuick_Ionospheric_Model|NeQuick-G ionospheric model]], whose high computational load poses a constraint in those user-segments where the user equipment has limited resources available. This is typically the case of the receivers used in civil aviation and location-based services (e.g., smartphones, UAVs, IoT devices).

The NTCM G electron density model was developed by the German Aerospace Center [https://www.dlr.de/en (DLR)]. The validation of NTCM G single-frequency ionospheric correction algorithm has been performed by DLR with the support of ESA, and the Joint Research Centre [https://joint-research-centre.ec.europa.eu (JRC)]<ref name="NTCMG_ICD2022">[https://www.gsc-europa.eu/sites/default/files/NTCM-G_Ionospheric_Model_Description_-_v1.0.pdf NTCM G Ionospheric Model Description, Issue 1.0, May 2022]</ref>.

The NTCM is an empirical model designed to provide a practical and cost-effective solution for estimating global TEC (Total Electron Content). It relies on 12 model coefficients (k₁ to k₁₂), a few fixed empirical parameters, and the solar radio flux index F10.7. To use the NTCM with the broadcast Galileo Effective Ionisation Level coefficients of the navigation message (aᵢ₀, aᵢ₁, aᵢ₂)<ref name="GALOSICD2023">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.1.pdf EU, SIGNAL-IN-SPACE INTERFACE CONTROL DOCUMENT, Issue 2.1, November 2023]</ref>, the F10.7 solar index is replaced by the term '''Azpar'''. This term is used as a proxy measure of the solar activity level and is determined as follows:
<math>
Azpar = \left| \sqrt{a_{i0}^2 + 1633.33 \cdot a_{i1}^2 + 4802000 \cdot a_{i2}^2 + 3266.67 \cdot a_{i0} \cdot a_{i2}} \right|
</math>

Where (aᵢ₀, aᵢ₁, aᵢ₂) are the three Effective Ionisation Level coefficients broadcast in the Galileo navigation message. The Azpar term is used to account for the solar activity dependency (F₅) in the estimation of VTEC (Vertical Total Electron Content) explained below.

NTCM G modeling approach consists of five major dependencies of TEC:
* Local time dependency (F₁)
* Seasonal dependency (F₂)
* Geomagnetic field dependency (F₃)
* Equatorial anomaly dependency (F₄)
* Solar activity dependency (F₅)

The dependencies are combined in a multiplicative way to compute a value of the VTEC:

<math>
VTEC_{NTCM-G} = F_1 \cdot F_2 \cdot F_3 \cdot F_4 \cdot F_5
</math>

Each F<sub>i</sub> factor contains the model coefficients (k₁ to k₁₂) for its computation, whose values are provided in Table 3 of the model description document<ref name="DLR2022">[https://www.gsc-europa.eu/sites/default/files/NTCM-G_Ionospheric_Model_Description_-_v1.0.pdf DLR, NTCM-G Ionospheric Model Description, mayo de 2022]</ref>.

===Input parameters===
The input parameters required by the NTCM G model to estimate each TEC dependency (F₁ to F₅), and consequently the VTEC value, include:
* Galileo Effective Ionisation Level coefficients (aᵢ₀, aᵢ₁, aᵢ₂)
* User receiver and satellite positions in WGS-84 ellipsoidal coordinates (φ<sub>u</sub>, λ<sub>u</sub>, h<sub>u</sub>) and (φ<sub>s</sub>, λ<sub>s</sub>, h<sub>s</sub>)
* Universal Time (UT)
* Day of Year (DOY)

The output of NTCM G is the VTEC in TECU for each line of sight between satellite and receiver.

The estimated VTEC output can be converted to STEC (Slant Total Electron Content) using the following equation:

<math>
STEC = MF_{MSLM} \cdot VTEC_{NTCM-G}
</math>

Where the Modified Single Layer Model (MSLM) mapping function is:

<math>
MF_{MSLM} = \frac{1}{\sqrt{1 - (\sin z)^2}}
</math>

<math>
\sin z = \frac{R_e}{R_e + h_I} \cdot \sin(0.9782 \cdot (\frac{\pi}{2} - E))
</math>

With:
* R<sub>e</sub> = 6371 km (Earth's mean radius)
* h<sub>I</sub> = 450 km (ionospheric pierce point height)
* E = satellite elevation angle in radians

=== Ionospheric Delay Calculation ===
Once the STEC is estimated, the ionospheric propagation delay (in meters) can be computed:

<math>
I_f = \frac{40.3 \cdot 10^{16}}{f^2} \cdot STEC
</math>

Where:
* ''f'' is the signal frequency in Hz
* The constant 40.3 is in m³/s²/electrons
* 10<sup>16</sup> converts TECU to electrons/m²

Higher-order ionospheric terms are generally neglected due to their small magnitude (e.g., < 20 cm for Galileo E1)<ref name="Hoque2008">M. M. Hoque y N. Jakowski, "Estimate of higher order ionospheric errors in GNSS positioning", Radio Sci., vol. 43, no. 5, 2008, doi:10.1029/2007RS003817.</ref>.

=== Algorithm Steps ===
To implement the ionospheric correction using NTCM G for Galileo single-frequency receivers, follow these steps<ref name="DLR2022" /> for each satellite-user line-of-sight:
# Obtain receiver (φ<sub>u</sub>, λ<sub>u</sub>, h<sub>u</sub>) and satellite (φ<sub>s</sub>, λ<sub>s</sub>, h<sub>s</sub>) positions, and Universal Time (UT), in terms of time of day and month.
# Compute Effectiove Ionization Level Azpar using the broadcast coefficients (aᵢ₀, aᵢ₁, aᵢ₂).
# Calculate satellite elevation (E) and azimuth (A) angles.
# Determine ionospheric pierce point location (φ<sub>pp</sub>, λ<sub>pp</sub>) for the user-to-satellite link at 450km height, and Local Time (LT).
# Use NTCM G to compute VTEC at (φ<sub>pp</sub>, λ<sub>pp</sub>), LT.
# Calculate mapping function (MF).
# Convert VTEC to STEC using the MF.
# Compute delay using equation for I<sub>f</sub> for the corresponfing frequency to obtain the correction.
# Apply correction to pseudorange.
# Repeat for each satellite.

Under normal ionospheric conditions, variations occur slowly, making high-rate recomputation of delay corrections unnecessary for most applications. A 30-second update interval is generally adequate for stationary receivers or pedestrian users applying the NTCM G ionospheric model.<ref name="DLR2022" />.

=== Performance ===
The performance of the NTCM G model has been validated and compared to the NeQuick-G model. Results indicate that NTCM G provides generally comparable and sometimes slightly better performance than NeQuick-G<ref name="DLR2022" />. Validation includes comparisons with ground-based VTEC maps from IGS (International GNSS Service), STEC observations, and SPP-based (Single Point Positioning) 3D positioning errors under various geographic and solar activity conditions.

::[[File: VTEC_RMS_NeQuick_vs_NTCM.png |800px|center|thumb|'''''Figure 1:''''' VTEC RMS residual error distribution in 2014 and 2015 for daytime hours 12-15 LT for NeQuick-G (left panel) and NTCM (right panel) <ref>M. M. Hoque, N. Jakowski, y J. A. Cahuasqui, «Fast Ionospheric Correction Algorithm for Galileo Single Frequency Users», 2020 Eur. Navig. Conf. ENC, pp. 1-10, nov. 2020, doi: 10.23919/ENC48637.2020.9317502.</ref> ]]
==References==
<references/>

[[Category:Fundamentals]]

Who is who

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__NOTOC__
<div style="text-align: center;"><span style="font-size:x-large; font-weight:normal;">Navipedia is maintained by the [https://gssc.esa.int/ ESA GNSS Science Support Centre].</span></div>
=History Contributors=
==The NAVIPEDIA Team==

===Project and Content Manager===
{|cellspacing="4" cellpadding="4"
|[[File:Guenter_H.png|100px|alt=Gunter Hein|link= ]]
|[[File:Javier_V1.jpg|100px|alt=Javier Ventura-Traveset|link= ]]
|-
|'''Günter Hein'''
|'''Javier Ventura-Traveset'''
|}

Günter and Javier have been in charge at ESA for the Project and Content Management of NAVIPEDIA

===The Vision===
[[File:Javier_V1.jpg|100px|alt=Javier Ventura-Traveset|link= ]]

'''Javier Ventura-Traveset'''

Javier was the one who had the idea of creating a knowledgebase of GNSS and making it available to users worldwide. It was Javier who came up with the name NAVIPEDIA.

===Editor===
[[File:Carlos.png|100px|alt=Carlos López de Echazarreta|link= ]]

'''Carlos López de Echazarreta'''

Carlos has been involved in the development of NAVIPEDIA since its inception and edited a large number of articles. Carlos is also responsible for the Content Development Plans and reviews articles submitted to NAVIPEDIA. He coordinated the ESA editorial team that included the following people:

:* Dr Günter Hein
:* Dr Javier Ventura-Traveset
:* Dr Bertram Arbesser
:* Rafael Lucas
:* Dr Jose Ángel Avila Rodríguez
:* Stefan Wallner
:* Michel Tossaint
:* Roberto Prieto

===Main NAVIPEDIA Contributors===
{|cellspacing="4" cellpadding="4"
|[[File:Jauma.png|100px|alt=Jaume Sanz Subirana|link= ]]
|[[File:Jose.png|100px|alt=Jose Ángel Ávila Rodríguez|link= ]]
|-
|'''Jaume Sanz Subirana'''
|'''Jose Ángel Ávila Rodríguez'''
|}
Jaume and Jose Ángel had a major contribution to the section of [[:Category:Fundamentals|GNSS Fundamentals]] in NAVIPEDIA. Their articles are the foundations of NAVIPEDIA.

{|cellspacing="4" cellpadding="4"
|[[File:Gmv_logo.png‎|100px|alt=GMV|link= ]]
|-
|'''GMV'''
|}
A large number of the NAVIPEDIA articles have been produced and edited by engineers and scientists from the company GMV.

===System Design===
{|cellspacing="4" cellpadding="4"
|[[File:Timo.jpg|100px|alt=Timo Kouwenhoven|link= ]]
|[[File:DNVGL Logo.png|250px|alt=DNV-GL logo|link=http://www.dnvgl.com/km]]
|-
|'''Timo Kouwenhoven (DNVGL)'''
|
|}
Timo is the technical expert behind NAVIPEDIA.

User Guides

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== What Is GNSS ==
:[[GNSS]]
==How Does GNSS Work?==
:[[An intuitive approach to the GNSS positioning]]
:[[GNSS signal]]
:[[GNSS Basic Observables]]
:[[Code Based Positioning (SPS)]]

==GNSS Receiver Basic Principles==
:[[GNSS Receivers General Introduction]]
:[[Generic Receiver Description]]
:[[Data Demodulation and Processing]]
:[[Receiver Characteristics]]

==Augmentation Systems==
:[[GNSS Augmentation]]
:[[SBAS General Introduction]]
:[[Ground-Based Augmentation System (GBAS)]]
:[[Differential GNSS]]

== Global Navigation Satellite Systems==
:[[Galileo General Introduction]]
:[[GPS General Introduction]]
:[[GLONASS General Introduction]]
:[[BeiDou General Introduction]]

== European GNSS Overview ==
;EGNOS
:[[EGNOS General Introduction]]
:[[EGNOS Future and Evolutions]]
:[[EGNOS Performances]]
:[[EGNOS Services]]
;Galileo
:[[GALILEO General Introduction]]
:[[GALILEO Services]]
:[[GALILEO Performances]]
:[[GALILEO Future and Evolutions]]

Main Page

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<div style="text-align: center;"><span style="font-size:x-large; font-weight:normal;">[[File:quoteOpen.png|super|link=]] The reference for Global Navigation Satellite Systems.[[File:quoteClose.png|super|link=]]</span></div>

{| style="width:100%" border="0" cellpadding="5" cellspacing="2" align="center"
|-

| style="width:60%; border:1px solid #d5d6d2; align:center; vertical-align:top" |
{| style="width:99%; border:3px solid #8b8d8e; border-top:none; border-left:none; border-right:none;" border="0" cellpadding="5" cellspacing="2" align="center" |
|-
|style="font-size:large; font-weight:bold;"|Browse Articles by Category
|}

{|style= "width:100%" cellpadding="5" cellspacing="2"
|-
|colspan=4|
{|style="width:99%; border:2px solid #d5d6d2; border-top:none; border-bottom:none; border-left:none; border-right:none;" border="0" cellpadding="0" align="center"
|align=center|[[File:Global-Navigation-Satellite-Systems.png|link= ]]
|}
|-
|align=center|[[File:GALILEO.png|100px|link=:Category:GALILEO|GALILEO]]
|align=center|[[File:GPS.png|100px|link=:Category:GPS|GPS]]
|align=center|[[File:GLONASS.png|100px|link=:Category:GLONASS|GLONASS]]
|align=center|[[File:BEIDOU.png|100px|link=:Category:BEIDOU|BEIDOU]]
|-
|colspan=4|
{|style="width:99%; border:2px solid #d5d6d2; border-bottom:none; border-left:none; border-right:none;" border="0" cellpadding="0" align="center"
|align=center|[[File:Satellite-Based-Augmentation-Systems.png|link= ]]
|}
|-
|align=center|[[File:EGNOS.png|100px|link=:Category:EGNOS|EGNOS]]
|align=center|[[File:WAAS.png|100px|link=:Category:WAAS|WAAS]]
|align=center|[[File:MSAS.png|100px|link=:Category:MSAS|MSAS]]
|align=center|[[File:Other SBAS.png|100px|link=:Category:Other SBAS|Other SBAS]]
|-
|colspan=4|
{|style="width:99%; border:2px solid #d5d6d2; border-bottom:none; border-left:none; border-right:none;" border="0" cellpadding="0" align="center"
|align=center|[[File:Regional-Navigation-Satellite-Systems.png|link= ]]
|}
|-
|align=center|[[File:IRNSS.png|100px|link=:Category:IRNSS|IRNSS]]
|align=center|[[File:QZSS.png|100px|link=:Category:QZSS|QZSS]]
|align=center|[[File:Other Regional Systems.png|100px|link=:Category:Other Regional Systems|Other Regional Systems]]
|
|-
|colspan=4|
{|style="width:99%; border:2px solid #d5d6d2; border-bottom:none; border-left:none; border-right:none;" border="0" cellpadding="0" align="center"
|align=center|[[File:Fundamentals-Receivers-and-Applications.png|link= ]]
|}
|-
|align=center|[[File:Fundamentals.png|100px|link=:Category:Fundamentals|Fundamentals]]
|align=center|[[File:Receivers.png|100px|link=:Category:Receivers|Receivers]]
|align=center|[[File:Applications.png|100px|link=:Category:Applications|Applications]]
|
|}



| style="width:40%; border:1px solid #d5d6d2; align:center; vertical-align:top" |
{|

{| style="width:99%; font-weight:bold; border:3px solid #8b8d8e; border-top:none; border-left:none; border-right:none;" border="0" cellpadding="5" cellspacing="2" align="center"
|-
| <span style="font-size:large; font-weight:bold;">News</span>
|}

{| style="width:99%; border:0px solid #8b8d8e;" border="0" cellpadding="0" cellspacing="0" align="center"
|-
* [http://www.esa.int/Our_Activities/Navigation/(archive) ESA Navigation news]
* [https://www.gsa.europa.eu/newsroom/news GSA news]
* [http://insidegnss.com/ Inside GNSS news]
* [http://gpsworld.com/ GPSWorld news]
* [https://gssc.esa.int/news/ GNSS Science Support Centre news]

|-

|}


{| style="width:99%; font-weight:bold; border:3px solid #8b8d8e; border-top:none; border-left:none; border-right:none;" border="0" cellpadding="5" cellspacing="2" align="center" -->
|-
| <span style="font-size:large; font-weight:bold;">GNSS Science Support Centre (GSSC)</span>
|}


{|style="width:99%" border="0" cellpadding="5" cellspacing="2" align="left"
|The GNSS Science Support Centre (GSSC) is a joint initiative of ESA’s Navigation and Science Directorates and a facility of part of their joint Navigation Science Office. [[GSSC|'''Read More''']]
|}


{| style="width:99%; font-weight:bold; border:3px solid #8b8d8e; border-top:none; border-left:none; border-right:none;" border="0" cellpadding="5" cellspacing="2" align="center"
|-






















| <span style="font-size:large; font-weight:bold;">Quick References</span>
|}


{|style="width:50%" border="0" cellpadding="5" cellspacing="2" align="left"
|
* [{{SERVER}}/navipedia/bookshelf/books/1.pdf GALILEO Brochure (ESA)]
* [{{SERVER}}/navipedia/bookshelf/books/2.pdf Current and Planned Global and Regional Navigation Systems (UNOOSA-ICG)]
* [{{SERVER}}/navipedia/bookshelf/books/4.pdf Galileo IOV Factsheet]
* [{{SERVER}}/navipedia/bookshelf/books/3.pdf Galileo FOC Factsheet]
* [[GNSS:Tools|ESA GNSS Data Processing Book]]
|}
{|style="width:50%" border="0" cellpadding="5" cellspacing="2" align="right"


|[[File:ESA GNSS Data Processing Vol I and II.gif|x220px|link=GNSS:Tools|ESA GNSS Data Processing Book]]
|}

|}

|}

GSSC

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{{Article Infobox2
|Category=Fundamentals
|Editors=GMV
|Level=Basic
|YearOfPublication=2021
|Logo=GMV
|Title={{PAGENAME}}
}}
The [//gssc.esa.int GNSS Science Support Centre (GSSC)] is a joint initiative of ESA’s Navigation and Science Directorates and a facility of part of their joint Navigation Science Office. The GSSC, hosted at the European Space Astronomy Centre near Madrid, integrates a wide range of GNSS assets including data, products and processing tools in a single environment promoting scientific collaboration and innovative research.

==History==
[[File:GSSC.jpeg‎|upright=1.5|thumb]]
The Navigation Science Office was set up in 2016 as a joint initiative between ESA’s Navigation and Science Directorates, coordinating scientific opportunities through interaction with the scientific community and ESA’s independent GNSS Science Advisory Committee.
Since the conception of the Navigation Science Office, the set-up of a dedicated facility, the GNSS Science Support Centre, supporting the implementation of its strategy lines, was considered a key objective. Announced in October 2017 at the 6th International Colloquium on Scientific and Fundamental Aspects of GNSS/Galileo, GSSC integrates IT and GNSS infrastructure to deliver advanced data and processing services for the scientific community.
In July 2018, GSSC initiated Pre-Operations providing a meeting point where the science community would be able to engage in activities carried out by the office such us:
* GBIGDATA - GNSS BIG DATA processing for monitoring, assessment of innovative techniques and science;
* GCROWD - GNSS CROWD sourcing applications for science;
* GESTA - GNSS Experiment for Scientific Tests in Antarctica;
* GREAT - GNSS General RElAtivity ExperimenT;
* GSSC Pilot - GNSS Science Thematic Exploitation Platform;
* WMCROWD - Weather Monitoring based on collaborative CROWDsourcing;
* NAVIPEDIA - NAVIgation WikiPEDIA;
All these activities have steadily contributed to GSSC in the form of data, products and analysis tools for GNSS Science.
In December 2018, GSSC moved into Operations, confirming ESA’s concrete answer to the need expressed by the scientific community for a "one-stop-shop" for long-term GNSS data, products, results of scientific experiments and analysis tools to enhance GNSS scientific research and collaboration.

==Mission==
GSSC supports adequate exploitation of the navigation systems infrastructure as a unique tool for scientific research. In addition, GSSC supports information exchange across the scientific community and ESA GNSS Teams.
Hence, GSSC aims at fostering the consolidation of a world-wide reference for the GNSS Scientific Community, maximising possibilities to perform GNSS Science activities and utilisation of European GNSS Infrastructures (Galileo & EGNOS).
The GSSC facility includes all the technological infrastructure required to efficiently provide GNSS data services, operational services with advanced archiving systems, scientific receivers data, GNSS data processors, training/education tools and access to ESA member states experts.

==GSSC's Thematic Exploitation Platform==
The core of the GSSC Project is a large GNSS repository, including global providers namely the International GNSS Service (IGS), regional ground-based GNSS receiver networks, space-based GNSS receivers from multiple missions and data from other services that can be of scientific use, such as laser ranging data from the International Laser Ranging Service (ILRS).
Since the start of operations in 2018, GSSC developments have leveraged on mainstream Big Data, Cloud, Virtualisation and Container technologies to implement the GSSC's Thematic Exploitation Platform. This platform evolves GSSC's repository with state-of-the-art discovery and analysis services to enable a paradigm shift characterised by moving the processing components closer to the data.
GSSC cyber-infrastructure allows the scientific community to extend processing systems executed at Data Centres, like quality checks and product generation, with new ones like [//jupyter.org Jupyter Notebooks] to carry out on-the-fly, interactive, data analysis without the need to download the data.

==Future and Evolution==
GSSC is to play a key role in ESA efforts to ensure long term access to GNSS scientific resources produced by ESA throughout the different research programmes, among which, for example, the innovative GNSS Intermediate Frequency Recording Station (GIFRES), which assesses feasibility of storing receiver's Intermediate Frequency (Big) data.
GSSC's Thematic Exploitation Platform (currently in the [//gssc.esa.int/news/gsscs-new-beginning-gnss-thematic-exploitation-platform Private Beta phase]) will be available to the public, extending community involvement for increased feedback and validation purposes. As soon as the feedback from users is injected into the final version and testing is complete, the Beta version will be declared production-ready.
GSSC will continue integrating outputs from GNSS projects such as:
* CAMALIOT - Application of Machine Learning Technology For GNSS IoT Data Fusion;
* GNSS Big Data - GNSS Big Data Processing for Monitoring, Assessment of Innovative Techniques and Science;
* UbiSAP - Ubiquitous Science Analytics Platform for IoT;
* Relativistic Positioning System - Study of the use of Intersatellite links in the definition of an autonomous system as part of the implementation of a Relativistic Positioning System;
* LIFELINE - Study on the feasibility and benefits of using a Relativistic Positioning System;
* A distributed network of Gamma-ray Burst detectors on Galileo;
* GASTON - Galileo Survey of Transient Objects Network (dark matter search);
* General Relativistic Effects in the orbits of Galileo Satellites;
* Requirements Definition Study for a Measurement of the Gravitomagnetic Clock Effect.
The GSSC is also expected to provide a major support to the scientific operations of all future GNSS-dedicated science missions on which ESA may be involved.

==Related Links==
For further information, please refer to the following links:<br>
https://gssc.esa.int/<br>
https://gssc.esa.int/news/gsscs-new-beginning-gnss-thematic-exploitation-platform/<br>

Content Management

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Vicente.Navarro: Protected "Content Management" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite))

==What is NAVIPEDIA?==
NAVIPEDIA is an electronic repository of knowledge related to GNSS. It is a common entry point, that enables users to access an updated information of the existing GNSS Systems, applications, receivers and fundamentals.
NAVIPEDIA adopts the concept of Media-wiki products. However, there is an important difference that distinguishes NAVIPEDIA from other wikies. A robust content management and control process ensures the needed quality, reliability and consistency of stored safety data.

==Generic Content Management Principles==
Developing NAVIPEDIA content and achieving the related targets requires well defined and systematic content management process. Content development needs are identified by research and monitoring of NAVIPEDIA user community needs, analysis of the current content and identification of missing knowledge elements or of existing knowledge elements, which need further enhancement. A Content Development Plans (CDP) have been established for all knowledge categories to ensure an efficient content development and update process, as well as an effective content development oversight. The CDP is subject to periodic review and update to ensure currency and comprehensiveness of NAVIPEDIA knowledgebase.

The task of content management is assigned to the NAVIPEDIA Content Manager.

==Content Quality Assurance==
The basic content management principle is that article content is developed using information derived from qualified sources. The article information source and the content control responsibility are indicated accordingly in the “Article Information” meta-data box, associated to each article and displayed in the upper right corner of the article page.
The integrity, consistency and correctness of article content are ensured through the formal compliance with the established:
* Article authorship, review and approval process and procedures
* Dedicated user rights management procedures and system support
* Procedure for peer review by NAVIPEDIA Fellows

The task of content quality assurance is assigned to the NAVIPEDIA Content Validation Manager.

==Article Creation and Upload==
Proposals for new articles, modifications to existing ones or new draft articles should be submitted to the Editor or Content manager through the “Contact us” feature of NAVIPEDIA, accessible from the left navigation bar.

The Editor only is entitled to integrate a draft article into the relevant NAVIPEDIA knowledge category following completion of article editorial and validation process.

==Article Review Cycle==
All NAVIPEDIA knowledge items, including articles are subject to review in order to ensure the required content quality, reliability, scope and relevance. The review process can be generally described as:
* '''''Random.''''' The review is carried out by the users and is not subject to control by the NAVIPEDIA development team. However, the recommendations and suggestions passed by the users will be given due consideration.
* '''''Periodic.''''' The review is carried out by the members of the NAVIPEDIA development team (Editor, Validation manager, Content manager, Moderator, Authors) in line with the established review procedure and schedule

Contact editor

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NAVIPEDIA is hosted by [https://gssc.esa.int/ GNSS Science Support Centre]

Please contact [https://gssc.esa.int/contact/ GSSC Contact and Support] for:
* All enquiries regarding editorial content or ideas for new articles.
* All enquiries regarding content development and content quality assurance.

Acronym List

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{{#get_db_data:
|server=serverID
|from=acronym
|where=acronym like '%'
|data=acro=acronym,mean=meaning}}

{| {{Prettytable}}
{{#for_external_table:<nowiki/>
{{!}}-
{{!}} [[{{{acro}}}]]
{{!}} {{{mean}}} }}
|}

About navipedia

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[[File:InsideGNSSNavipedia.jpg|right|thumb|500px|link=http://www.insidegnss.com/node/3265|Navipedia in [http://www.insidegnss.com/node/3265 Inside GNSS] Magazine]]
== '''What is NAVIPEDIA?''' ==
NAVIPEDIA is an initiative of the European Space Agency aiming at becoming the reference for Global Navigation Satellite Systems general knowledge on the Internet. It is conceived as a collaborative GNSS encyclopaedia with the objective to foster the transfer of knowledge in the field of GNSS

NAVIPEDIA is an electronic repository of knowledge related to GNSS. It is a common entry point, that enables users to access updated information of the existing GNSS Systems, applications, receivers and fundamentals.

NAVIPEDIA adopts the concept of Media-wiki products. However, there is an important difference that distinguishes NAVIPEDIA from other wikies. A robust content management and control process ensures the needed quality, reliability and consistency of stored GNSS information.

NAVIPEDIA is hosted by the [https://gssc.esa.int/home/ GNSS Science Support Centre].

More detailed information on content development and quality assurance procedures can be obtained from the dedicated article on [[Content Management]].

NAVIPEDIA content development priorities remain, being focused on:
* '''Who''': GNSS
* '''Where''': Globally
* '''What''': GNSS Systems, GNSS Fundamentals, GNSS Applications, GNSS Receivers
* '''GNSS Community''': General users, University, GNSS expert users, GNSS Industry, and GNSS Application developers

Our Content Development objectives were to achieve core GNSS subject coverage in the following categories:
* ''GNSS Systems'': Galileo, GPS, GLONASS, BeiDou
* ''Augmented GNSS Systems'': EGNOS, WAAS, MSAS, GAGAN and SDCM
* ''GNSS Fundamentals''
* ''GNSS Applications''
* ''GNSS Receivers''

== NAVIPEDIA Partners ==
NAVIPEDIA has been initiated by ESA in partnership with the following organisations:
* [http://www.oosa.unvienna.org UNOOSA] – United Nations Office for Outer Space Affairs

The initiative aims at developing a comprehensive source of GNSS information and making it available to users worldwide.

== NAVIPEDIA's Strategic Objective ==
NAVIPEDIA's objective is to become a single point of reference for GNSS knowledge. The NAVIPEDIA knowledgebase is a dynamic enterprise and has taken several years to develop. To develop further, and maintain the accuracy and relevance of the knowledgebase, will require the support and active participation of all those interested in promoting best practice and knowledge in GNSS.

== The NAVIPEDIA team ==
The NAVIPEDIA content development team has a wealth of experience in GNSS. To learn more about the individuals who have contributed knowledge to, and guided the development of, NAVIPEDIA see the separate page "[[Who is who]]".

== The NAVIPEDIA wiki platform ==
NAVIPEDIA is set up as a wiki, using the same platform as wikipedia, with some additions and some restrictions. If you want to learn more, do check Help.
If you would like to contribute an article to NAVIPEDIA, click [[Contact editor|here]]

Help:Contents

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{|
|width="18%" valign="top"|
;Reading
*[[Help:Navigation|Navigation]]
*[[Help:Searching|Searching]]
*[[Help:Tracking changes|Tracking changes]]
|width="18%" valign="top"|
;Editing
*[[Help:Starting a new page|Starting a new page]]
*[[Help:Writing a navipedia article|Writing a navipedia article]]
*[[Help:Editing pages|Editing pages]]
*[[Help:Formatting|Formatting]]
*[[Help:Links|Links]]
*[[Help:Categories|Categories]]
|width="18%" valign="top"|
;Advanced Editing
*[[Help:Images|Images]]
*[[Help:Tables|Tables]]
*[[Help:Templates|Templates]]
*[[Help:Variables|Variables]]
*[[Help:Managing files|Managing files]]
*[[Help:Colours|Colours]]
|width="18%" valign="top"|
;Customizing
*[[Help:Preferences|Preferences]]
*[[Help:Skins|Skins]]
|width="18%" valign="top"|
;Administration
*[[Help:Interwiki linking|Interwiki linking]]
*[[Help:Namespaces|Namespaces]]
*[[Help:User accounts|User accounts]]
|width="18%" valign="top"|
;Other
*[[Help:Math|Math]]
*[[Help:Footnotes|Footnotes]]
*[[Help:ApprovedRevs|Approved Revisions]]
*[[Help:Books|Books]]
|}

For help with Navipedia editing, see the [[:File:Navipedia_Help_Document.pdf|editing guide in PDF]].

===Current categories in use===
{|
|width="25%" valign="top"|
; GNSS
* GNSS Fundamentals
|width="25%" valign="top"|
; GALILEO
* GALILEO Fundamentals
|width="25%" valign="top"|
; GBAS
* GBAS Fundamentals
|-
|width="25%" valign="top"|
; EGNOS
* EGNOS Fundamentals
|width="25%" valign="top"|
; GPS
* GPS Fundamentals
|width="25%" valign="top"|
; GLONASS
* GLONASS Fundamentals
|-
|width="25%" valign="top"|
; Resources
* Icon
* Diagram
* Illustration
* Graph
|width="25%" valign="top"|
;Miscellaneous
* General
* Help
|}

__NOTOC__
__NOEDITSECTION__

[[Category:Help]]

Writing a navipedia article

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#REDIRECT [[Help:Writing a navipedia article]]

Help:Writing a navipedia article

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Vicente.Navarro: Vicente.Navarro moved page Writing a navipedia article to Help:Writing a navipedia article

This article provides general guidance on writing articles for NAVIPEDIA.

==Do You Have Author Rights?==
Whether a user can create new pages depends on the rights of the user group he or she belongs to. If you do not have the appropriate author rights, or are not comfortable writing in wiki mark-up language, you can still contribute articles to NAVIPEDIA by sending your material, in Microsoft Word , to the [https://gssc.esa.int/navipedia/index.php/Contact_editor editor]

The editor will then place your article in '''Work in Progress'''.

New articles are created in the '''Work in Progress''' section and, once approved, are moved by the editor to the main section of NAVIPEDIA. If you have been granted the appropriate rights, you can place your article directly into '''Work in Progress'''. For information on how to do this, see the help page: [[Help:Starting a new page]].

==Guidance on Writing an Article==
While the majority of NAVIPEDIA visitors are general public looking for GNSS information or GNSS professionals such as engineers, professors, etc.., not all of them speak English as a first language. Authors should therefore avoid complicated language and the use of words which are not in common usage.

As an example of a typical article using this structure click here.

If you have any questions about writing and submitting articles, contact the [https://gssc.esa.int/navipedia/index.php/Contact_editor Editor]

[[Category:Help]]

Help:Writing a navipedia article

2025-07-14T07:58:40Z

Vicente.Navarro:

Galileo Safety of Life (SoL)

2025-07-14T07:56:52Z

Vicente.Navarro:

As of 2011, the SoL service is being re-profiled, one of the solutions under assessment being [[ARAIM|ARAIM]].

[[Category:GALILEO]]
[[Category:GALILEO Integrity]]

Galileo Integrity Concept

2025-07-14T07:55:57Z

Vicente.Navarro:

{{Article Infobox2
|Category=Fundamentals
|Authors=GMV
|Level=Basic
|YearOfPublication=2013
|Logo=GMV
|Title={{PAGENAME}}
}}
As of 2011, the SoL service is being re-profiled, one of the solutions under assessment being [[ARAIM]].

[[Category:Fundamentals]]
[[Category:GALILEO]]
[[Category:GALILEO Integrity]]

Category:GALILEO Integrity

2025-07-14T07:54:47Z

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MediaWiki:Centralnotice-template-Maintenance

2025-07-10T10:00:21Z

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MediaWiki:Centralnotice-template-Maintenance

2025-05-23T15:03:59Z

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<h3 style="margin-top: 0;">🔧 Planned Maintenance Notification 🔧</h3>
<p>Please be advised that a scheduled maintenance window is planned for
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<p>During this period, Navipedia may experience
<strong style="color: #e67e22;">intermittent availability issues</strong>.
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<p>We apologise for any inconvenience this may cause and appreciate your understanding as we work to improve our systems.</p>
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MSAS Signal Structure

2025-04-23T07:49:42Z

Vicente.Navarro:

{{Article Infobox2
|Category=MSAS
|Editors=GMV
|Level=Basic
|YearOfPublication=2011
|Logo=GMV
|Title={{PAGENAME}}
}}
The MTSAT Satellite Augmentation System ([[MSAS General Introduction|MSAS]]) is the Japanese [[SBAS General Introduction|Satellite Based Augmentation System (SBAS)]] System, a GNSS Augmentation system with the goal of improving its accuracy, integrity, and availability.
First tests were accomplished successfully, and MSAS system for aviation use was declared operational in September 27, 2007,<ref name="MSAS_STATUS_2007_2">QZSS / MSAS Status, CGSIC –47th Meeting ,Fort Worth, Texas September25, 2007, Satoshi KOGURE, [http://www.jaxa.jp/index_e.html Japan Aerospace Exploration Agency,] QZSS Project Team</ref><ref name="MSAS_GPSW">[http://www.gpsworld.com/surveyperspectives-late-april-2008-7289 Eric Gakstatter, Perspectives - Late April 2008, GPSworld, April 15, 2008]</ref><ref name=MSAS_WIKI_2>[http://en.wikipedia.org/wiki/Multi-functional_Satellite_Augmentation_System Multi-functional Satellite Augmentation System] in [http://en.wikipedia.org/ Wikipedia]</ref> providing a service of horizontal guidance for En-route through Non-Precision Approach.
The SBAS signal used to be transmitted from MTSAT (Multi-functional Transport Satellites) operated by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). The SBAS signal that is made by MLIT is now transmitted from the QZS-3 GEO satellite using the QZSS SBAS transmission service since April 2020.<ref name="QZSS_SBAS">[https://qzss.go.jp/en/overview/services/sv12_sbas.html SBAS Transmission Service], QZSS Official Website</ref>

==MSAS Signal Structure==

[[SBAS Fundamentals|Signal characteristics]] are compliant with ICAO Standards and Recommended Practices (SARPs), Annex 10 - Aeronautical Telecommunications, Volume I - Radio Navigational Aids, July 2023.
*Frequency ; L1 = 1575.42MHz.
*Bandwidth ; L1 ±2.2 MHz band.
*Data Rate; 500 symbols per Second, 1/2 convolutional encoded with a Forward Error Correction (FEC) code (250 effective bits per second).
*Signal strength on the earth surface >-161dBw at 5 degrees elevation.

The future lines of improvement of MSAS signals are:
*Band width expansion for L1.
*DFMC L5 SBAS experiments are being conducted successfully, confirming that L5 SBAS augments multi-constellation of GPS + GLONASS + Galileo + BeiDou + QZSS. <ref name="QZSS_Update">[https://www.unoosa.org/documents/pdf/icg/2018/icg13/06.pdf QZSS Update] ICG-13 Providers System and Service Updates, Nov. 5, 2018, Xi’an, China
</ref>

For an introduction on the signal structure, please refer to the article [[The EGNOS SBAS Message Format Explained]].

==Notes==
<references group="footnotes"/>
==References==
<references/>

[[Category:MSAS]]

MSAS Signal Structure

2025-04-23T07:47:14Z

Vicente.Navarro:

{{Article Infobox2
|Category=MSAS
|Editors=GMV
|Level=Basic
|YearOfPublication=2011
|Logo=GMV
|Title={{PAGENAME}}
}}
The MTSAT Satellite Augmentation System ([[MSAS General Introduction|MSAS]]) is the Japanese [[SBAS General Introduction|Satellite Based Augmentation System (SBAS)]] System:<ref name="MSAS_STATUS_2007">[http://www.unoosa.org/ MSAS Current Status, Japan Civil Aviation Bureau,] [http://www.oosa.unvienna.org/oosa/SAP/gnss/icg/icg02/presentations.html Second Meeting of the International Committee on Global Navigation Satellite Systems (ICG) organized by the International Space Research Organization, Bangalore, India , 5 - 7 September 2007]</ref> a GPS Augmentation system with the goal of improving its accuracy, integrity, and availability.
First tests were accomplished successfully, and MSAS system for aviation use was declared operational in September 27, 2007,<ref name="MSAS_STATUS_2007_2">QZSS / MSAS Status, CGSIC –47th Meeting ,Fort Worth, Texas September25, 2007, Satoshi KOGURE, [http://www.jaxa.jp/index_e.html Japan Aerospace Exploration Agency,] QZSS Project Team</ref><ref name="MSAS_GPSW">[http://www.gpsworld.com/surveyperspectives-late-april-2008-7289 Eric Gakstatter, Perspectives - Late April 2008, GPSworld, April 15, 2008]</ref><ref name=MSAS_WIKI_2>[http://en.wikipedia.org/wiki/Multi-functional_Satellite_Augmentation_System Multi-functional Satellite Augmentation System] in [http://en.wikipedia.org/ Wikipedia]</ref> providing a service of horizontal guidance for En-route through Non-Precision Approach.
The SBAS signal used to be transmitted from MTSAT (Multi-functional Transport Satellites) operated by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). The SBAS signal that is made by MLIT is now transmitted from the QZS-3 GEO satellite using the QZSS SBAS transmission service since April 2020.<ref name="QZSS_SBAS">[https://qzss.go.jp/en/overview/services/sv12_sbas.html SBAS Transmission Service], QZSS Official Website</ref>

==MSAS Signal Structure==

[[SBAS Fundamentals|Signal characteristics]] are compliant with ICAO Standards and Recommended Practices (SARPs), Annex 10 - Aeronautical Telecommunications, Volume I - Radio Navigational Aids, July 2023.
*Frequency ; L1 = 1575.42MHz.
*Bandwidth ; L1 ±2.2 MHz band.
*Data Rate; 500 symbols per Second, 1/2 convolutional encoded with a Forward Error Correction (FEC) code (250 effective bits per second).
*Signal strength on the earth surface >-161dBw at 5 degrees elevation.

The future lines of improvement of MSAS signals are:<ref name="MSAS_STATUS_2008"/>
*Band width expansion for L1.
*DFMC L5 SBAS experiments are being conducted successfully, confirming that L5 SBAS augments multi-constellation of GPS + GLONASS + Galileo + BeiDou + QZSS. <ref name="QZSS_Update">[https://www.unoosa.org/documents/pdf/icg/2018/icg13/06.pdf QZSS Update] ICG-13 Providers System and Service Updates, Nov. 5, 2018, Xi’an, China
</ref>

For an introduction on the signal structure, please refer to the article [[The EGNOS SBAS Message Format Explained]].

==Notes==
<references group="footnotes"/>
==References==
<references/>

[[Category:MSAS]]

GBAS Fundamentals

2025-04-23T07:43:08Z

Vicente.Navarro:

{{Article Infobox2
|Category=Fundamentals
|Editors=GMV
|Level=Basic
|YearOfPublication=2011
|Logo=GMV
|Title={{PAGENAME}}
}}
A [[Ground-Based Augmentation System (GBAS)]] is a civil-aviation safety-critical system that supports local augmentation –at airport level– of the primary GNSS constellation(s) by providing enhanced levels of service that support all phases of approach, landing, departure and surface operations. While the main goal of GBAS is to provide [[Integrity|integrity]] assurance, it also increases the [[Accuracy|accuracy]] with position errors below 1 m (1 sigma).<ref name="GNSS Aug">[[Wikipedia:GNSS augmentation|GNSS augmentation in Wikipedia]]</ref><ref name="Kaplan">E.D. Kaplan, C.J. Hegarty, ''Understanding GPS Principles and Applications”, 2nd Ed., Artch House, ISBN 1-58053-894-0, 2006.</ref>

The Ground Based Augmentation System (GBAS) is intended primarily to support precision approach operations. It consists of a GBAS Ground Subsystem and a GBAS Aircraft Subsystem.

==Introduction: How a GBAS works==
(The information in this section has been taken from [http://www.faa.gov/ FAA] homepage.)

A Ground Based Augmentation System (GBAS) augments the Global Positioning System (GPS) to improve aircraft safety during airport approaches and landings. It is expected that the end-state configuration will pinpoint the aircraft's position to within one meter or less with a significant improvement in service flexibility and user operating costs. GBAS is comprised of ground equipment and avionics. The ground equipment includes 4 reference receivers, a GBAS ground facility, and a VHF data broadcast transmitter. This ground equipment is complemented by GBAS avionics installed on the aircraft.<ref>[http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/laas/howitworks/ LAAS-How it works] by FAA.</ref>

Signals from GPS satellites are received by the GBAS GPS Reference Receivers at the GBAS-equipped airport. The reference receivers calculate their position using GPS. The GPS Reference Receivers and GBAS Ground Facility work together to measure errors in GPS-provided position. The GBAS Ground Facility produces a GBAS correction message based on the difference between actual and GPS-calculated position which includes as well integrity parameters and approach path information. This GBAS correction message is then sent to a VHF data broadcast (VDB) transmitter.

The VDB broadcasts the GBAS signal throughout the GBAS coverage area to avionics in GBAS-equipped aircraft. GBAS provides its service to a local area (approximately a 30 kilometer radius). The signal coverage is designed to support the aircraft's transition from en route airspace into and throughout the terminal area airspace.

The GBAS equipment in the aircraft uses the corrections provided on position, velocity, and time to guide the aircraft safely to the runway. This signal provides ILS-look-alike guidance as low as 200 feet (60 m) above touchdown. GBAS will eventually support landings all the way to the runway surface.

<gallery>
Image:Laas_step1.jpg‎
Image:Laas_step2.jpg‎
Image:Laas_step3.jpg‎
Image:Laas_step4.jpg‎
</gallery>

==GBAS Architecture==
[[File:LAAS_Architecture.png|GBAS architecture|350px|thumb|right]]

A GBAS is a safety critical system designed to augment one or several satellite navigation systems. The main components of a general GBAS architecture are:
* GBAS Ground Subsystem
* GBAS Aircraft Subsystem
* GNSS Satellites Subsystem

===GBAS Ground Subsystem===

The main purposes of the GBAS Ground Subsystem are:
*reception and decoding of signals-in-space;
*computation of the differential corrections to the carrier-smoothed codes;
*integrity monitoring;
*generation and broadcasting of GBAS messages.

The GBAS Ground Subsystem consists of:
*2 to 4 GNSS Reference Receivers and their respective geographically separated antennas;
*A VHF data broadcast (VDB) transmitter;
*A monitor system;
*Approach Database (FAS data);
*Ground processing functions.

===GBAS Aircraft Subsystem===

The main element of GBAS Aircraft Subsystem is the aircraft GBAS Receivers.

The primary functions of the GBAS aircraft subsystem are:
* receive and decode the GNSS satellite and GBAS signals;
* determine the aircraft position;
* provide availability of the service;
* compute deviations from the desired flight path calculated from the Final Approach Segment (FAS) data;
* provide guidance signals and integrity information.

The GBAS aircraft subsystem essential elements are:
* An Aircraft GNSS Receiver Function that receives, tracks, and decodes the GNSS satellite signals.
* A VHF Data Broadcast Receiver Function that receives and decodes the messages broadcast by the GBAS Ground Subsystem.
* An Aircraft Navigation Processing Function that receives the measurement of the pseudo-ranges from the GNSS Receiver Function, applies the differential corrections received from the VHF Data Broadcast Receiver Function and calculates the differentially corrected aircraft position. The Aircraft Navigation Processing Function extracts from the different FAS path construction data received, the one having the Reference Path Selector selected by the crew through the GLS Channel Number Selector. The Aircraft Navigation Processing Function also calculates deviations from the selected FAS path based on its differentially corrected position.

===GNSS Satellites Subsystem===

The GBAS Satellites Subsystem is mainly the GNSS constellations declared operational for civil use. The minimum requirements of a GBAS system are limited for the use of GNSS satellites ranging sources, with additional ranging sources being supplied by SBAS as an option.

==GBAS Signal==

The GBAS Signal in Space is defined to be only the data broadcast from the ground to the aircraft subsystem. The Satellite Signals in Space are part of the basic GNSS satellite constellations.

The GBAS ground subsystem differential computed corrections (contained in Type 1 message), GBAS ground subsystem related data (contained in Type 2 message) and Final Approach Segments (FAS) (contained in Type 4 message) are transmitted to the aircraft users via VHF Data Broadcast (VDB) Signal. The GBAS Messages are encoded in this signal. The specification of GBAS message data format is contained in the [https://www.icao.int ICAO] Standards and Recommended Practices (SARPS) in Annex 10, Volume I, Appendix B for the aspects related with the signal in space, as well as in the RTCA MOPS DO-253C for the minimum operational performance requirements applicable to the airborne GBAS receiver equipment and EUROCAE ED-114A MOPS for Global Navigation Satellite Ground Based Augmentation System Ground Equipment to Support Category I Operations.

The VDB radio frequencies used shall be selected from the radio frequencies in the band 108-117.975 MHz. The lowest assignable frequency shall be 108.025 MHz and the highest frequency assignable shall be 117.950 MHz. The separation between assignable frequencies (channel spacing) shall be 25 kHz.

The GBAS message types are summarized in the following table:

{| class="wikitable" align="center"
!Message type identifier
!Message Name
|-align="center"
|0
| Spare
|-align="center"
|1
| GBAS Differential Corrections
|-align="center"
|2
| GBAS Related Data
|-align="center"
|3
| Reserved for ground–based ranging source
|-align="center"
|4
| Final Approach Segment (FAS) data
|-align="center"
|5
| Predicted ranging source availability
|-align="center"
|6
| Reserved
|-align="center"
|7
| Reserved for national applications
|-align="center"
|8
| Reserved for test applications
|-align="center"
|9-255
| Spare
|}

==GBAS Performances==

The GBAS performances are defined with respect to the level of service that the system is designed to provide. The main source for GBAS performances comes from civil aviation navigation safety requirements and they are different for each civil aviation operation, as specified in ICAO Standards and Recommended Practices (SARPs), Annex 10 - Aeronautical Telecommunications, Volume I - Radio Navigational Aids, July 2023.

{| class="wikitable"
|-
!Typical Operation
!Horizontal Accuracy (95%)
!Vertical Accuracy (95%)
!Integrity
!Time-To-Alert (TTA)
!Continuity
!Availability
|-
|Initial approach, Intermediate approach, Non-precision approach (NPA), Departure
|align="center"|220m (720ft)
|align="center"|N/A
|align="center"|1–1×10<sup>-7</sup>/h
|align="center"|10s
|align="center"|1–1×10<sup>-4</sup>/h to 1–1×10<sup>-8</sup>/h
|align="center"|0.99 to 0.99999
|-
|Non Precision Approach with vertical guidance (NPV-I)
|align="center"| 220m (720ft)
|align="center"| 20m (66ft)
|align="center"| 1–2×10<sup>-7</sup> per approach
|align="center"| 10s
|align="center"| 1–8×10<sup>-6</sup> in any 15s
|align="center"| 0.99 to 0.99999
|-
|Non Precision Approach with vertical guidance (NPV-II)
|align="center"| 16m (52ft)
|align="center"| 8m (26ft)
|align="center"| 1–2×10<sup>-7</sup> per approach
|align="center"| 6s
|align="center"| 1–8×10<sup>-6</sup> in any 15s
|align="center"| 0.99 to 0.99999
|-
|Category I (CAT-I) Precision Approach
|align="center"| 16m (52ft)
|align="center"| 6.0m to 4.0m (20ft to 13ft)
|align="center"| 1–2×10<sup>-7</sup> per approach
|align="center"| 6s
|align="center"| 1–8×10<sup>-6</sup> in any 15s
|align="center"| 0.99 to 0.99999
|}

Usually a GBAS system is designed to fulfil CAT-I Precision Approach.

As indicated in the table above, the performance requirements are expressed in terms of four quantitative concepts, many of them to be interpreted as probabilistic figures:
* '''Accuracy''': is expressed in terms of Navigation System Error (NSE) as the difference between the real position of the aircraft and the position provided by the airborne equipment.
* '''Integrity''': is defined by [https://www.icao.int ICAO] as a measure of the trust that can be placed in the correctness of the information supplied by the system.

* '''Continuity''': is the probability that the specified system performance will be maintained for the duration of a phase of operation, presuming that the system was available at the beginning of that phase of operation and was predicted to operate throughout the operation. Lack of continuity means that the operation must be aborted (with the associated risk).
* '''Availability''': is the probability that the navigation service is available at the beginning of the planned operation. A GBAS system is considered available when the accuracy, integrity and continuity requirements are met throughout the coverage region.

==Notes==
<references group="footnotes"/>

==References==
<references/>

[[Category:Fundamentals]]
[[Category:GBAS]]

GBAS Fundamentals

2025-04-23T07:37:24Z

Vicente.Navarro:

{{Article Infobox2
|Category=Fundamentals
|Editors=GMV
|Level=Basic
|YearOfPublication=2011
|Logo=GMV
|Title={{PAGENAME}}
}}
A [[Ground-Based Augmentation System (GBAS)]] is a civil-aviation safety-critical system that supports local augmentation –at airport level– of the primary GNSS constellation(s) by providing enhanced levels of service that support all phases of approach, landing, departure and surface operations. While the main goal of GBAS is to provide [[Integrity|integrity]] assurance, it also increases the [[Accuracy|accuracy]] with position errors below 1 m (1 sigma).<ref name="GNSS Aug">[[Wikipedia:GNSS augmentation|GNSS augmentation in Wikipedia]]</ref><ref name="Kaplan">E.D. Kaplan, C.J. Hegarty, ''Understanding GPS Principles and Applications”, 2nd Ed., Artch House, ISBN 1-58053-894-0, 2006.</ref>

The Ground Based Augmentation System (GBAS) is intended primarily to support precision approach operations. It consists of a GBAS Ground Subsystem and a GBAS Aircraft Subsystem.

==Introduction: How a GBAS works==
(The information in this section has been taken from [http://www.faa.gov/ FAA] homepage.)

A Ground Based Augmentation System (GBAS) augments the Global Positioning System (GPS) to improve aircraft safety during airport approaches and landings. It is expected that the end-state configuration will pinpoint the aircraft's position to within one meter or less with a significant improvement in service flexibility and user operating costs. GBAS is comprised of ground equipment and avionics. The ground equipment includes 4 reference receivers, a GBAS ground facility, and a VHF data broadcast transmitter. This ground equipment is complemented by GBAS avionics installed on the aircraft.<ref>[http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/laas/howitworks/ LAAS-How it works] by FAA.</ref>

Signals from GPS satellites are received by the GBAS GPS Reference Receivers at the GBAS-equipped airport. The reference receivers calculate their position using GPS. The GPS Reference Receivers and GBAS Ground Facility work together to measure errors in GPS-provided position. The GBAS Ground Facility produces a GBAS correction message based on the difference between actual and GPS-calculated position which includes as well integrity parameters and approach path information. This GBAS correction message is then sent to a VHF data broadcast (VDB) transmitter.

The VDB broadcasts the GBAS signal throughout the GBAS coverage area to avionics in GBAS-equipped aircraft. GBAS provides its service to a local area (approximately a 30 kilometer radius). The signal coverage is designed to support the aircraft's transition from en route airspace into and throughout the terminal area airspace.

The GBAS equipment in the aircraft uses the corrections provided on position, velocity, and time to guide the aircraft safely to the runway. This signal provides ILS-look-alike guidance as low as 200 feet (60 m) above touchdown. GBAS will eventually support landings all the way to the runway surface.

<gallery>
Image:Laas_step1.jpg‎
Image:Laas_step2.jpg‎
Image:Laas_step3.jpg‎
Image:Laas_step4.jpg‎
</gallery>

==GBAS Architecture==
[[File:LAAS_Architecture.png|GBAS architecture|350px|thumb|right]]

A GBAS is a safety critical system designed to augment one or several satellite navigation systems. The main components of a general GBAS architecture are:
* GBAS Ground Subsystem
* GBAS Aircraft Subsystem
* GNSS Satellites Subsystem

===GBAS Ground Subsystem===

The main purposes of the GBAS Ground Subsystem are:
*reception and decoding of signals-in-space;
*computation of the differential corrections to the carrier-smoothed codes;
*integrity monitoring;
*generation and broadcasting of GBAS messages.

The GBAS Ground Subsystem consists of:
*2 to 4 GNSS Reference Receivers and their respective geographically separated antennas;
*A VHF data broadcast (VDB) transmitter;
*A monitor system;
*Approach Database (FAS data);
*Ground processing functions.

===GBAS Aircraft Subsystem===

The main element of GBAS Aircraft Subsystem is the aircraft GBAS Receivers.

The primary functions of the GBAS aircraft subsystem are:
* receive and decode the GNSS satellite and GBAS signals;
* determine the aircraft position;
* provide availability of the service;
* compute deviations from the desired flight path calculated from the Final Approach Segment (FAS) data;
* provide guidance signals and integrity information.

The GBAS aircraft subsystem essential elements are:
* An Aircraft GNSS Receiver Function that receives, tracks, and decodes the GNSS satellite signals.
* A VHF Data Broadcast Receiver Function that receives and decodes the messages broadcast by the GBAS Ground Subsystem.
* An Aircraft Navigation Processing Function that receives the measurement of the pseudo-ranges from the GNSS Receiver Function, applies the differential corrections received from the VHF Data Broadcast Receiver Function and calculates the differentially corrected aircraft position. The Aircraft Navigation Processing Function extracts from the different FAS path construction data received, the one having the Reference Path Selector selected by the crew through the GLS Channel Number Selector. The Aircraft Navigation Processing Function also calculates deviations from the selected FAS path based on its differentially corrected position.

===GNSS Satellites Subsystem===

The GBAS Satellites Subsystem is mainly the GNSS constellations declared operational for civil use. The minimum requirements of a GBAS system are limited for the use of GNSS satellites ranging sources, with additional ranging sources being supplied by SBAS as an option.

==GBAS Signal==

The GBAS Signal in Space is defined to be only the data broadcast from the ground to the aircraft subsystem. The Satellite Signals in Space are part of the basic GNSS satellite constellations.

The GBAS ground subsystem differential computed corrections (contained in Type 1 message), GBAS ground subsystem related data (contained in Type 2 message) and Final Approach Segments (FAS) (contained in Type 4 message) are transmitted to the aircraft users via VHF Data Broadcast (VDB) Signal. The GBAS Messages are encoded in this signal. The specification of GBAS message data format is contained in the [https://www.icao.int ICAO] SARPS Appendix B for the aspects related with the signal in space, as well as in the RTCA MOPS DO-253C for the minimum operational performance requirements applicable to the airborne GBAS receiver equipment.

The VDB radio frequencies used shall be selected from the radio frequencies in the band 108-117.975 MHz. The lowest assignable frequency shall be 108.025 MHz and the highest frequency assignable shall be 117.950 MHz. The separation between assignable frequencies (channel spacing) shall be 25 kHz.

The GBAS message types are summarized in the following table:

{| class="wikitable" align="center"
!Message type identifier
!Message Name
|-align="center"
|0
| Spare
|-align="center"
|1
| GBAS Differential Corrections
|-align="center"
|2
| GBAS Related Data
|-align="center"
|3
| Reserved for ground–based ranging source
|-align="center"
|4
| Final Approach Segment (FAS) data
|-align="center"
|5
| Predicted ranging source availability
|-align="center"
|6
| Reserved
|-align="center"
|7
| Reserved for national applications
|-align="center"
|8
| Reserved for test applications
|-align="center"
|9-255
| Spare
|}

==GBAS Performances==

The GBAS performances are defined with respect to the level of service that the system is designed to provide. The main source for GBAS performances comes from civil aviation navigation safety requirements and they are different for each civil aviation operation, as specified in ICAO Standards and Recommended Practices, Annex 10 - Aeronautical Telecommunications, Volume I - Radio Navigational Aids, July 2023.

{| class="wikitable"
|-
!Typical Operation
!Horizontal Accuracy (95%)
!Vertical Accuracy (95%)
!Integrity
!Time-To-Alert (TTA)
!Continuity
!Availability
|-
|Initial approach, Intermediate approach, Non-precision approach (NPA), Departure
|align="center"|220m (720ft)
|align="center"|N/A
|align="center"|1–1×10<sup>-7</sup>/h
|align="center"|10s
|align="center"|1–1×10<sup>-4</sup>/h to 1–1×10<sup>-8</sup>/h
|align="center"|0.99 to 0.99999
|-
|Non Precision Approach with vertical guidance (NPV-I)
|align="center"| 220m (720ft)
|align="center"| 20m (66ft)
|align="center"| 1–2×10<sup>-7</sup> per approach
|align="center"| 10s
|align="center"| 1–8×10<sup>-6</sup> in any 15s
|align="center"| 0.99 to 0.99999
|-
|Non Precision Approach with vertical guidance (NPV-II)
|align="center"| 16m (52ft)
|align="center"| 8m (26ft)
|align="center"| 1–2×10<sup>-7</sup> per approach
|align="center"| 6s
|align="center"| 1–8×10<sup>-6</sup> in any 15s
|align="center"| 0.99 to 0.99999
|-
|Category I (CAT-I) Precision Approach
|align="center"| 16m (52ft)
|align="center"| 6.0m to 4.0m (20ft to 13ft)
|align="center"| 1–2×10<sup>-7</sup> per approach
|align="center"| 6s
|align="center"| 1–8×10<sup>-6</sup> in any 15s
|align="center"| 0.99 to 0.99999
|}

Usually a GBAS system is designed to fulfil CAT-I Precision Approach.

As indicated in the table above, the performance requirements are expressed in terms of four quantitative concepts, many of them to be interpreted as probabilistic figures:
* '''Accuracy''': is expressed in terms of Navigation System Error (NSE) as the difference between the real position of the aircraft and the position provided by the airborne equipment.
* '''Integrity''': is defined by [https://www.icao.int ICAO] as a measure of the trust that can be placed in the correctness of the information supplied by the system.

* '''Continuity''': is the probability that the specified system performance will be maintained for the duration of a phase of operation, presuming that the system was available at the beginning of that phase of operation and was predicted to operate throughout the operation. Lack of continuity means that the operation must be aborted (with the associated risk).
* '''Availability''': is the probability that the navigation service is available at the beginning of the planned operation. A GBAS system is considered available when the accuracy, integrity and continuity requirements are met throughout the coverage region.

==Notes==
<references group="footnotes"/>

==References==
<references/>

[[Category:Fundamentals]]
[[Category:GBAS]]

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