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{{Article Infobox2
{{Article Infobox2
|Category=EGNOS
|Category=EGNOS
|Title={{PAGENAME}}
|Editors=GMV
|Authors=GMV.
|Level=Basic
|Level=Basic
|YearOfPublication=2011
|YearOfPublication=2011
|Logo=GMV
|Logo=GMV
|Title={{PAGENAME}}
}}
}}
SISNeT is a technology that combines the powerful capabilities of satellite navigation and the Internet. The accurate navigation and integrity information that comes from the EGNOS (European Geostationary Navigation Overlay Service) Signal-In-Space (SIS) is available over the Internet and in real time via SISNeT.<ref name=" ESA SISNeT Portal">[http://www.egnos-pro.esa.int/sisnet/index.html  ESA SISNeT Portal ]</ref> Today, SISNeT is included in [[EGNOS Data Access Service (EDAS)|EDAS service]].


 
EGNOS broadcasts augmentation signals for GNSS through Geostationary Earth Orbit (GEO) satellites. GEO broadcasting is proved to be an efficient strategy for avionic applications and other modes of transport. For some applications, though, it may be of interest to complement GEO broadcasting through other transmission means. For instance, building obstacles in cities or rural canyons may difficult the GEO reception. In those situations, complementary real-time Internet-based broadcasting of the EGNOS signal is of major interest as a way to continue taking the most of the EGNOS potential, irrespectively of the user environment.<ref name=" The ESA SISNeT Project: Current Status and Future Plans">The ESA SISNeT Project: Current Status and Future Plans; Félix Torán-Martí and Javier Ventura-Traveset ESA GNSS-1 Project Office. European Space Agency (ESA). Toulouse (France). </ref>
SISNeT is a technology that combines the powerful capabilities of satellite navigation and the Internet. The highly accurate navigation information that comes from the EGNOS (European Geostationary Navigation Overlay Service) Signal-In-Space (SIS) is now available over the Internet and in real time via SISNeT.<ref name=" ESA SISNeT Portal">[http://www.egnos-pro.esa.int/sisnet/index.html  ESA SISNeT Portal ]</ref>
 
EGNOS broadcasts augmentation signals for GPS through Geostationary Earth Orbit (GEO) satellites. GEO broadcasting is proved to be an efficient strategy for avionic applications and other modes of transport. For some applications, though, it may be of interest to complement GEO broadcasting through other transmission means. For instance, building obstacles in cities or rural canyons may difficult the GEO reception. In those situations, complementary real-time Internet-based broadcasting of the EGNOS signal is of major interest as a way to continue taking the most of the EGNOS potential, irrespectively of the user environment.<ref name=" The ESA SISNeT Project: Current Status and Future Plans">The ESA SISNeT Project: Current Status and Future Plans; Félix Torán-Martí and Javier Ventura-Traveset ESA GNSS-1 Project Office. European Space Agency (ESA). Toulouse (France). </ref>


Responding to that need, ESA developed and launched the SISNeT service in 2002. SISNeT allows retrieving the EGNOS messages across the Internet in real-time, usually through wireless networks, like GSM or GPRS. Thanks to SISNeT, any user with access to the Internet (e.g. through wireless GSM or GPRS networks) may access the EGNOS product, irrespectively of the GEO visibility conditions.
Responding to that need, ESA developed and launched the SISNeT service in 2002. SISNeT allows retrieving the EGNOS messages across the Internet in real-time, usually through wireless networks, like GSM or GPRS. Thanks to SISNeT, any user with access to the Internet (e.g. through wireless GSM or GPRS networks) may access the EGNOS product, irrespectively of the GEO visibility conditions.
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In the early days of SISNeT, advanced simulation activities revealed that the combination of EGNOS and the almost unlimited capabilities of the Internet could open the door to a lot of innovative applications for Satellite Navigation. The evolution of SISNeT to the date has demonstrated and justified what simulations were anticipating, mainly thanks to:
In the early days of SISNeT, advanced simulation activities revealed that the combination of EGNOS and the almost unlimited capabilities of the Internet could open the door to a lot of innovative applications for Satellite Navigation. The evolution of SISNeT to the date has demonstrated and justified what simulations were anticipating, mainly thanks to:
[[File:SISNeT.jpg | EGNOS access through SISNeT.  |320px|thumb|left]]


* The launch of a number of ESA contracts with European industry, on SISNeT developments.
* The launch of a number of ESA contracts with European industry, on SISNeT developments.
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* The ESA internal work on SISNeT.
* The ESA internal work on SISNeT.


In fact, new application fields based on SISNeT have been identified, like educational applications, help to impaired people, quick initialisation of SBAS receivers, etc. The possibilities of SISNeT have revealed to be beyond ESA initial expectations.
In fact, new application fields based on SISNeT were identified, like educational applications, help to impaired people, quick initialisation of SBAS receivers, etc. The possibilities of SISNeT revealed to be beyond ESA initial expectations.


On the other hand, the Scientific and Engineering community may find major advantages in using SISNeT: the EGNOS signal can be received and processed without having to invest in an EGNOS receiver. Just a connection to the Internet is necessary. These benefits are also applicable to Educational environments (e.g. laboratory exercises based on the EGNOS signal do not imply acquiring receivers, only requiring computers connected to the Internet).
On the other hand, the Scientific and Engineering community may find major advantages in using SISNeT: the EGNOS signal can be received and processed without having to invest in an EGNOS receiver. Just a connection to the Internet is necessary. These benefits are also applicable to Educational environments (e.g. laboratory exercises based on the EGNOS signal do not imply acquiring receivers, only requiring computers connected to the Internet).
Line 33: Line 29:
==Current SISNeT Status==
==Current SISNeT Status==


For a wide range of EGNOS applications it may be of interest to complement GEO broadcasting through other transmission means. For instance, building obstacles in cities or rural canyons may difficult the GEO reception. In those situations, complementary means of broadcasting (e.g. FM, Digital Audio Broadcasting – DAB – and the Internet) have a remarkable interest. In this context, the European Space Agency (ESA) launched an internal project to provide access to the EGNOS messages in real time
For a wide range of EGNOS applications it may be of interest to complement GEO broadcasting through other transmission means. For instance, building obstacles in cities or rural canyons may difficult the GEO reception. In those situations, complementary means of broadcasting (e.g. FM, Digital Audio Broadcasting – DAB – and the Internet) have a remarkable interest. In this context, the European Space Agency (ESA)<ref name=" ESA Web Site">[http://www.esa.int/esaCP/index.html  ESA Web Site ]</ref> launched an internal project to provide access to the EGNOS messages in real time through the Internet. The product of this project was a new technology, called SISNeT (Signal in Space through the Internet), whose interest has greatly grown since the initial SISNet service was put in place by ESA in 2001.
through the Internet. The product of this project has been a new technology, called SISNeT (Signal in Space through the Internet), whose interest has greatly grown since the initial SISNet service was put in place by ESA in 2001.


A first prototype of the SISNeT concept was set-up by the ESA GNSS-1 Project Office, in 2001. Since February 2002, the SISNeT service is accessible through the open Internet, via an authentication procedure. SISNeT accounts are free of charge, and can be requested by contacting the SISNeT team at SISNET@esa.int. Each account consists on a username, a password, the IP address of the SISNeT Data Server and the port to use. The SISNeT project is managed from the EGNOS Project Office (Toulouse, France), where the full platform design and development takes place. Maintenance of the SISNeT platform components is performed from the ESA ESTEC centre (Noordwijk, The Netherlands).
A first prototype of the SISNeT concept was set-up by the ESA GNSS-1 Project Office, in 2001. Since February 2002, the SISNeT service is accessible through the open Internet, via an authentication procedure.
Currently, SISNet is nowadays integrated in EDAS service. Please refer to EDAS Service Definition document<ref name=" EDAS SDD">[https://egnos-user-support.essp-sas.eu/new_egnos_ops/sites/default/files/library/official_docs/egnos_edas_sdd_in_force.pdf  EDAS SDD ]</ref> for guidelines for the access and usage of the EDAS SISNet service.


Providing online access to sharpened satnav accuracy, ESA’s SISNeT system has entered its 10th year of operations.<ref name=" ESA news on SISNeT">[http://www.esa.int/esaNA/SEMFKYFMTGG_egnos_0.html   ESA news on SISNeT System ]</ref>
The SISNet status can be consulted through EDAS in EGNOS monitoring website from ESSP.<ref name=" EDAS Status">[https://egnos-user-support.essp-sas.eu/new_egnos_ops/services/edas-service/realtime   EDAS Status ]</ref>  


==Deployed SISNeT Applications==
==Deployed SISNeT Applications==


The SISNeT project can grant important advantages to the GPS land-user community as a user equipped with a GPS receiver and a GSM (or GPRS) modem can access the SISNeT services, thus being able to benefit from the EGNOS augmentation signals, even under situations of GEO blocking. A series of SISNeT based projects have been successfully completed, some of which are briefly described hereafter:<ref name=" The ESA SISNeT Project: Current Status and Future Plans"></ref>
The SISNeT project can grant important advantages to the GPS land-user community as a user equipped with a GPS receiver and a GSM (or GPRS) modem can access the SISNeT services, thus being able to benefit from the EGNOS augmentation signals, even under situations of GEO blocking. A series of SISNeT based projects were successfully completed, some of which are briefly described hereafter:<ref name=" The ESA SISNeT Project: Current Status and Future Plans"></ref>


* '''Handheld SISNeT receiver'''.<ref name=" Handheld Internet-Based EGNOS Receiver">Handheld Internet-Based EGNOS Receiver: The First Product of the ESA SISNET Technology; F. Toran, J. Ventura-Traveset and R. Chen; GNSS 2003, Graz (Austria), 22 – 25 April 2003. </ref> <ref name=" Navigate via the Web with the SISNeT receiver">Navigate via the Web with the SISNeT receiver: ESA Press Release, 6 September 2002, European Space Agency. Available at (http://www.esa.int/export/esaSA/ESAW0OZPD4D_navigation_0.html)  </ref> <ref name=" Access to the EGNOS Signal In Space Over Mobile-IP">Access to the EGNOS Signal In Space Over Mobile-IP; R. Chen, F. Toran-Marti and J. Ventura-Traveset. GPS Solutions (2003). </ref> This device is based on a Pocket PC Personal Digital Assistant (PDA) device. It includes a GPS card, and the Internet is reached through a GSM / GPRS wireless modem. Specific software is embedded, combining GPS measurements with the EGNOS corrections got via SISNeT. As a result, position accuracy is considerably improved.


[[File: ShPIDER_receiver.JPG| SISNeT-based ShPIDER receiver  |250px|thumb|right]]
[[File: ShPIDER_receiver.JPG| SISNeT-based ShPIDER receiver  |250px|thumb|right]]


* '''SISNeT technology applied to fleet management'''.<ref name=" Toulouse bus test-drives European satellite navigation">Toulouse bus test-drives European satellite navigation; ESA Press Release, 14 February 2003, available at (http://www.esa.int/export/esaSA/SEM4HZ1A6BD_navigation_0.html). </ref> A one-box handheld SISNeT receiver was developed, based on a Psion NetPad device, equipped with the Windows CE .net operating system.A mechanical adaptation was made to integrate a GPS receiver chipset. The link to the Internet is achieved through an integrated GSM / GPRS modem. Almost any commercial GIS software can be used with SISNeT positioning, thanks to a specific driver.
* '''Handheld SISNeT receiver'''.<ref name=" Handheld Internet-Based EGNOS Receiver">Handheld Internet-Based EGNOS Receiver: The First Product of the ESA SISNET Technology; F. Toran, J. Ventura-Traveset and R. Chen; GNSS 2003, Graz (Austria), 22 – 25 April 2003. </ref> <ref name=" Navigate via the Web with the SISNeT receiver">[http://www.esa.int/Our_Activities/Navigation/Navigate_via_the_web_with_the_SISNeT_receiver Navigate via the Web with the SISNeT receiver: ESA Press Release, 6 September 2002, European Space Agency.]</ref> <ref name=" Access to the EGNOS Signal In Space Over Mobile-IP">Access to the EGNOS Signal In Space Over Mobile-IP; R. Chen, F. Toran-Marti and J. Ventura-Traveset. GPS Solutions (2003). </ref> This device is based on a Pocket PC Personal Digital Assistant (PDA) device. It includes a GPS card, and the Internet is reached through a GSM / GPRS wireless modem. Specific software is embedded, combining GPS measurements with the EGNOS corrections got via SISNeT. As a result, position accuracy is considerably improved.
 
* '''SISNeT technology applied to fleet management'''.<ref name=" Toulouse bus test-drives European satellite navigation">[http://www.esa.int/Our_Activities/Navigation/Toulouse_bus_test-drives_European_satellite_navigation Toulouse bus test-drives European satellite navigation; ESA Press Release, 14 February 2003.]</ref> A one-box handheld SISNeT receiver was developed, based on a Psion NetPad device, equipped with the Windows CE .net operating system. A mechanical adaptation was made to integrate a GPS receiver chipset. The link to the Internet is achieved through an integrated GSM / GPRS modem. Almost any commercial GIS software can be used with SISNeT positioning, thanks to a specific driver.
 
* '''Application of the SISNeT technology to help blind pedestrians'''. This activity consisted on assessing the feasibility of applying the SISNeT concept to improve the performance of a navigation device for the blind. The selected device, called TORMES, was developed by the Spanish company GMV and ONCE (the Spanish organisation for the blind) before the start of the activity.<ref name=" Space technology to help the blind">[http://www.esa.int/esaNA/ESAKN58708D_egnos_0.html Space technology to help the blind; ESA Press Release, 30 December 2003.]</ref> <ref name=" Blind Pedestrian Navigator: Operating Features, Performances and EGNOS / SISNET Benefits">Blind Pedestrian Navigator: Operating Features, Performances and EGNOS / SISNET Benefits; Catalina A., March J., Davila R., Paniagua J., Busnadiego C., Ventura-Traveset J., Toran-Marti F., Fernandez-Coya J.L., Lorente J.L.; Proceedings of GNSS 2003, Graz (Austria), 22 – 25 April 2003.</ref>


* '''Application of the SISNeT technology to help blind pedestrians'''. This activity consisted on assessing the feasibility of applying the SISNeT concept to improve the performance of a navigation device for the blind. The selected device, called TORMES, was developed by the Spanish company GMV Sistemas and ONCE (the Spanish organisation for the blind) before the start of the activity.<ref name=" Space technology to help the blind">Space technology to help the blind; ESA Press Release, 30 December 2003,
* '''EDAS SISNeT Service''': The EDAS SISNeT service provides access to messages from EGNOS GEO satellites transmitted through the Internet using the SISNeT protocol, a full description of which is available in the SISNeT User Interface Document. Specific guidelines on how to access and use the EDAS SISNeT service are available in the EDAS SISNeT User Information Package. <ref>https://egnos-user-support.essp-sas.eu/new_egnos_ops/services/about-edas</ref>
available at (http://www.esa.int/export/esaSA/SEM4HZ1A6BD_navigation_0.html). </ref> <ref name=" Blind Pedestrian Navigator: Operating Features, Performances and EGNOS / SISNET Benefits">Blind Pedestrian Navigator: Operating Features, Performances and EGNOS / SISNET Benefits; Catalina A., March J., Davila R., Paniagua J., Busnadiego C., Ventura-Traveset J., Toran-Marti F., Fernandez-Coya J.L., Lorente J.L.; Proceedings of GNSS 2003, Graz (Austria), 22 – 25 April 2003.</ref>


==Potential SISNeT Applications==
==Potential SISNeT Applications==


ESA has also identified additional benefits that could be obtained from SISNeT, remarking the following:
ESA also identified additional benefits that could be obtained from SISNeT, remarking the following:


* The indoor penetration of wireless networks as GSM or GPRS offers a lot of benefits for SBAS receiver initialisation. For vehicles, the SBAS receiver can be initialised in the garage, being ready to use (with EGNOS corrections) once reaching the street.
* The indoor penetration of wireless networks as GSM or GPRS offers a lot of benefits for SBAS receiver initialisation. For vehicles, the SBAS receiver can be initialised in the garage, being ready to use (with EGNOS corrections) once reaching the street.
Line 61: Line 59:
* Prior to reaching the urban environment (e.g. while a vehicle is in the garage or a person is inside a building), the GPS ephemeris information can be initialised from SISNeT, instead of waiting for the GPS message to be received (once on the urban scenario), reducing very much then the time to first fix.
* Prior to reaching the urban environment (e.g. while a vehicle is in the garage or a person is inside a building), the GPS ephemeris information can be initialised from SISNeT, instead of waiting for the GPS message to be received (once on the urban scenario), reducing very much then the time to first fix.


However, SISNeT remains a prototype system, with no guaranteed service levels. In order to cover this necessity, [[EGNOS Data Access Service (EDAS) | EGNOS Data Access Service (EDAS)]] is offering reliable performance levels on a warranty basis.
SISNeT started as a prototype system, although currently it is an operational one.  


EDAS has been developed by the European Commission with ESA technical support and it offers a next step for services initially based on SISNeT.
==Credits==
This article has been mainly based on information published by ESA, according to the references cited.


==Notes==
==Notes==

Latest revision as of 08:20, 18 March 2020


EGNOSEGNOS
Title SISNET
Edited by GMV
Level Basic
Year of Publication 2011
Logo GMV.png

SISNeT is a technology that combines the powerful capabilities of satellite navigation and the Internet. The accurate navigation and integrity information that comes from the EGNOS (European Geostationary Navigation Overlay Service) Signal-In-Space (SIS) is available over the Internet and in real time via SISNeT.[1] Today, SISNeT is included in EDAS service.

EGNOS broadcasts augmentation signals for GNSS through Geostationary Earth Orbit (GEO) satellites. GEO broadcasting is proved to be an efficient strategy for avionic applications and other modes of transport. For some applications, though, it may be of interest to complement GEO broadcasting through other transmission means. For instance, building obstacles in cities or rural canyons may difficult the GEO reception. In those situations, complementary real-time Internet-based broadcasting of the EGNOS signal is of major interest as a way to continue taking the most of the EGNOS potential, irrespectively of the user environment.[2]

Responding to that need, ESA developed and launched the SISNeT service in 2002. SISNeT allows retrieving the EGNOS messages across the Internet in real-time, usually through wireless networks, like GSM or GPRS. Thanks to SISNeT, any user with access to the Internet (e.g. through wireless GSM or GPRS networks) may access the EGNOS product, irrespectively of the GEO visibility conditions.

SISNeT Advantages

In the early days of SISNeT, advanced simulation activities revealed that the combination of EGNOS and the almost unlimited capabilities of the Internet could open the door to a lot of innovative applications for Satellite Navigation. The evolution of SISNeT to the date has demonstrated and justified what simulations were anticipating, mainly thanks to:

  • The launch of a number of ESA contracts with European industry, on SISNeT developments.
  • The interest of worldwide companies, organisations and universities on applying SISNeT to a large variety of applications, research and development projects.
  • The ESA internal work on SISNeT.

In fact, new application fields based on SISNeT were identified, like educational applications, help to impaired people, quick initialisation of SBAS receivers, etc. The possibilities of SISNeT revealed to be beyond ESA initial expectations.

On the other hand, the Scientific and Engineering community may find major advantages in using SISNeT: the EGNOS signal can be received and processed without having to invest in an EGNOS receiver. Just a connection to the Internet is necessary. These benefits are also applicable to Educational environments (e.g. laboratory exercises based on the EGNOS signal do not imply acquiring receivers, only requiring computers connected to the Internet).

Another advantage is centred in the low bandwidth requirements of SISNeT: the transfer rate ranges from 300 bps to 700 bps, being 470 bps the average value. These characteristics make SISNeT very adequate to be used with GSM / GPRS wireless networks.

Current SISNeT Status

For a wide range of EGNOS applications it may be of interest to complement GEO broadcasting through other transmission means. For instance, building obstacles in cities or rural canyons may difficult the GEO reception. In those situations, complementary means of broadcasting (e.g. FM, Digital Audio Broadcasting – DAB – and the Internet) have a remarkable interest. In this context, the European Space Agency (ESA)[3] launched an internal project to provide access to the EGNOS messages in real time through the Internet. The product of this project was a new technology, called SISNeT (Signal in Space through the Internet), whose interest has greatly grown since the initial SISNet service was put in place by ESA in 2001.

A first prototype of the SISNeT concept was set-up by the ESA GNSS-1 Project Office, in 2001. Since February 2002, the SISNeT service is accessible through the open Internet, via an authentication procedure. Currently, SISNet is nowadays integrated in EDAS service. Please refer to EDAS Service Definition document[4] for guidelines for the access and usage of the EDAS SISNet service.

The SISNet status can be consulted through EDAS in EGNOS monitoring website from ESSP.[5]

Deployed SISNeT Applications

The SISNeT project can grant important advantages to the GPS land-user community as a user equipped with a GPS receiver and a GSM (or GPRS) modem can access the SISNeT services, thus being able to benefit from the EGNOS augmentation signals, even under situations of GEO blocking. A series of SISNeT based projects were successfully completed, some of which are briefly described hereafter:[2]


SISNeT-based ShPIDER receiver
  • Handheld SISNeT receiver.[6] [7] [8] This device is based on a Pocket PC Personal Digital Assistant (PDA) device. It includes a GPS card, and the Internet is reached through a GSM / GPRS wireless modem. Specific software is embedded, combining GPS measurements with the EGNOS corrections got via SISNeT. As a result, position accuracy is considerably improved.
  • SISNeT technology applied to fleet management.[9] A one-box handheld SISNeT receiver was developed, based on a Psion NetPad device, equipped with the Windows CE .net operating system. A mechanical adaptation was made to integrate a GPS receiver chipset. The link to the Internet is achieved through an integrated GSM / GPRS modem. Almost any commercial GIS software can be used with SISNeT positioning, thanks to a specific driver.
  • Application of the SISNeT technology to help blind pedestrians. This activity consisted on assessing the feasibility of applying the SISNeT concept to improve the performance of a navigation device for the blind. The selected device, called TORMES, was developed by the Spanish company GMV and ONCE (the Spanish organisation for the blind) before the start of the activity.[10] [11]
  • EDAS SISNeT Service: The EDAS SISNeT service provides access to messages from EGNOS GEO satellites transmitted through the Internet using the SISNeT protocol, a full description of which is available in the SISNeT User Interface Document. Specific guidelines on how to access and use the EDAS SISNeT service are available in the EDAS SISNeT User Information Package. [12]

Potential SISNeT Applications

ESA also identified additional benefits that could be obtained from SISNeT, remarking the following:

  • The indoor penetration of wireless networks as GSM or GPRS offers a lot of benefits for SBAS receiver initialisation. For vehicles, the SBAS receiver can be initialised in the garage, being ready to use (with EGNOS corrections) once reaching the street.
  • In addition, when crossing long tunnels (or other segments with no GPS / GEO satellite visibility) SBAS/SISNeT receiver can start getting the necessary information before leaving the tunnel, since GSM /GPRS signals are normally accessible before reaching the exit. Considering the capability to retrieve previously broadcast messages via SISNeT, the SBAS system can be immediately used after leaving the tunnel in most of the cases, and the benefits of GEO ranging available without delay, just immediately after the EGNOS GEO(s) are again in visibility.
  • Prior to reaching the urban environment (e.g. while a vehicle is in the garage or a person is inside a building), the GPS ephemeris information can be initialised from SISNeT, instead of waiting for the GPS message to be received (once on the urban scenario), reducing very much then the time to first fix.

SISNeT started as a prototype system, although currently it is an operational one.

Credits

This article has been mainly based on information published by ESA, according to the references cited.

Notes

References

  1. ^ ESA SISNeT Portal
  2. ^ a b The ESA SISNeT Project: Current Status and Future Plans; Félix Torán-Martí and Javier Ventura-Traveset ESA GNSS-1 Project Office. European Space Agency (ESA). Toulouse (France).
  3. ^ ESA Web Site
  4. ^ EDAS SDD
  5. ^ EDAS Status
  6. ^ Handheld Internet-Based EGNOS Receiver: The First Product of the ESA SISNET Technology; F. Toran, J. Ventura-Traveset and R. Chen; GNSS 2003, Graz (Austria), 22 – 25 April 2003.
  7. ^ Navigate via the Web with the SISNeT receiver: ESA Press Release, 6 September 2002, European Space Agency.
  8. ^ Access to the EGNOS Signal In Space Over Mobile-IP; R. Chen, F. Toran-Marti and J. Ventura-Traveset. GPS Solutions (2003).
  9. ^ Toulouse bus test-drives European satellite navigation; ESA Press Release, 14 February 2003.
  10. ^ Space technology to help the blind; ESA Press Release, 30 December 2003.
  11. ^ Blind Pedestrian Navigator: Operating Features, Performances and EGNOS / SISNET Benefits; Catalina A., March J., Davila R., Paniagua J., Busnadiego C., Ventura-Traveset J., Toran-Marti F., Fernandez-Coya J.L., Lorente J.L.; Proceedings of GNSS 2003, Graz (Austria), 22 – 25 April 2003.
  12. ^ https://egnos-user-support.essp-sas.eu/new_egnos_ops/services/about-edas