European Geostationary Navigation Overlay Service
European Geostationary Navigation Overlay Service ( EGNOS ) is a European Differential Global Positioning System (DGPS) as an extension system for satellite navigation . It increases the positional accuracy of GNSS regionally limited to Europe and is functionally and protocol-wise fully compatible with the American WAAS , the Japanese MSAS and the Indian GAGAN , which also distribute their correction data via satellites ( Satellite Based Augmentation System , SBAS). Reception of EGNOS requires a line of sight to a geostationary satellite in the south.
In addition to data to improve position accuracy, EGNOS also provides information about the integrity of the GNSS: users of the Safety-of-Life service find out within 6 seconds if the positioning systems are sending incorrect data or reception is severely disturbed. The Safety of Life service is used when correct position information is vital, such as in air traffic.
background
After the artificial phase fluctuations of the civilly usable C / A code were switched off by GPS ( Selective Availability ) in May 2000, the largest remaining sources of error are runtime effects in the ionosphere . The speed of the radio signals from the GNSS satellites when passing through the ionosphere depends on the degree of ionization . The transit time therefore depends not only on the distance to the satellite, but also on the ionospheric state. This effect could be corrected by comparing the transit times on two or more different GNSS transmission frequency bands, but civil, portable navigation devices usually only receive the signal from the GNSS satellites on one frequency band. The Broadcom BCM 47755 chip, which came onto the market in 2018, is considered to be the first two-frequency band GNSS receiver suitable for the mass market.
Conventional differential GPS , based on a single reference station with a known position, allows a highly accurate correction, but only at a short distance from this station. The tomographic linking of the transit times observed by many reference stations leads to an interpolating map of the electron density of the ionosphere, which allows the recipients to make a rough correction in the entire area covered by the reference stations.
System structure
EGNOS ground stations
40 reference stations ( Ranging and Integrity Monitoring Station , RIMS ) in Europe, North Africa and the Middle East receive the signals from GPS, GLONASS and Galileo satellites. Since the stations are typically much farther apart than the height of the ionosphere, in order to cover the entire ionosphere they have to receive the satellites up to just above the horizon. Special choke ring antennas are used to suppress disruptive multi-path reception caused by reflections on the floor .
Two redundant control centers ( Master Control Center , MCC ) near Madrid and Rome use the data from the RIMS to calculate both satellite position corrections and current maps of the electron density of the ionosphere for time correction .
Six up-link stations ( Navigation Land Earth Station , NLES ), two redundant per satellite orbit, send the correction data to the geostationary satellites for area-wide distribution.
EGNOS satellites
Transponders currently in operation
The following geostationary satellites broadcast the EGNOS correction signal:
| EGNOS operation | PRN | ID | Signals | Orbit position | satellite | comment |
|---|---|---|---|---|---|---|
| Test mode | 120 | 33 | L1 | 15.5 ° west | Inmarsat-3F2, AOR-E | started on September 6, 1996, EGNOS operation since March 2, 2011 |
| Service of Life | 136 | 49 | L1, L5 | 5.0 ° East | SES-5 | started on July 9, 2012, EGNOS operation since August 13, 2015 |
| Service of Life | 123 | 36 | L1, L5 | 31.5 ° East | Astra-5B | started on March 22, 2014, EGNOS operation since December 11, 2014 |
In addition to the regular EGNOS signal, which has been broadcast since 2006, the EGNOS signal from one of the satellites is only intended for test purposes (EGNOS System Test Bed (ESTB)).
So that simple GNSS receivers do not need an additional receiving unit, the geostationary satellites send the correction data on the GPS L1 frequency. For separation by means of CDMA , C / A codes from PRN 120 are used, regular GPS satellites use the identification range from 1 to 32.
To increase the positioning accuracy, paths should be chosen during surveying or navigation work in such a way that there is a line of sight to at least one EGNOS satellite for a long time at the starting point and areas with complete shadowing are avoided or quickly crossed.
Out of order transponders
In the past, a signal was also sent via the satellites ARTEMIS (PRN 124; ID 37) and Inmarsat IND-W (PRN 126; ID 39).
Distribution of EGNOS correction data via the Internet
Since the geostationary satellites are not high in the sky in Europe and their signals are therefore difficult to receive, especially for mobile users in cities, the data is also distributed promptly over the Internet.
All data records sent are archived and are freely available via FTP . This allows the subsequent correction ( postprocessing ) of GNSS positions (if GNSS raw data were recorded ) and facilitates application development.
The correction data distributed free of charge in this way only has a low data rate. The much more extensive raw data of all RIMS are available for a fee via an access point. They allow a more precise correction, especially in the RIMS environment, and have guaranteed availability.
EGNOS compatible GNSS receivers
Many GNSS receivers support the reception of the EGNOS correction signal via the EGNOS satellites and can process the EGNOS correction data. If there is no line of sight to an EGNOS satellite, high-quality GNSS receivers allow the EGNOS correction data to be received via mobile communications from the Internet. Use of the EGNOS Open Service is free.
The design specification is based on the fact that 99% of the determined positions are within a circle with a 40 meter radius around the true position. If this accuracy can no longer be guaranteed due to system anomalies, a warning is issued within six seconds.
EGNOS versions
EGNOS v2
The system has been in official operation since October 1, 2009. The release for safety-of-life applications was announced for 2010. In July 2010 the signal was certified for system integrity, but the go live initially failed (at the beginning of August) due to a software error. This signal has been sent since December 2010 and has been used by the provider since March 2, 2011. On December 15, 2011, the Federal Supervisory Office for Air Traffic Control (BAF) for Germany gave its approval for the use of the Safety-of-Life service .
The characteristic values of the Safety of Life service with EGNOS v2-compatible GNSS receivers are:
- Correction data for: GPS L1 C / A
- Accuracy (horizontal): 3 meters (with 95% probability)
- Accuracy (vertical): 4 meters (with 95% probability)
The operation of the Safety of Life service with EGNOS v2-compatible GNSS receivers is guaranteed until 2030.
EGNOS v3
On November 20, 2013, the European Parliament approved the further funding of EGNOS and the Galileo satellite navigation system in the amount of 7 billion euros for the period 2014-2020. Airbus is working with several partners on EGNOS v3, an evolutionary stage of the system that will increase the position accuracy of both GPS and Galileo . EGNOS v3 will support the correction data for two different frequency bands: L1 / E1 (1575 MHz) and L5 / E5 (1176 MHz). EGNOS v3 will also support dual frequency band GNSS receivers for the Safety of Life service , which increases position accuracy.
The characteristic values of the Safety of Life service with EGNOS v3-compatible GNSS receivers are:
- Correction data for: GPS L1, GPS L5, Galileo E1 and Galileo E5
- Accuracy (Horizontal): probably <1 meter
- Accuracy (vertical): probably <1 meter
From 2023 to 2025 , EGNOS v3 is to be put into operation in several stages.
administration
EGNOS is a joint project of ESA , the EU and the European air traffic control Eurocontrol , who jointly prepared the project as the European Tripartite Group (ETP). It is regarded as the entry of the Europeans into satellite navigation and as a preliminary stage to the European satellite navigation system Galileo . ESA is responsible for design and development. European Satellite Service Provider SAS (ESSP), based in Toulouse (France), operates and markets EGNOS on behalf of the EU.
literature
- Javier Ventura-Traveset, Didier Flament (Ed.): EGNOS: The European Geostationary Navigation Overlay System - A cornerstone of Galileo. ESA Publications Division, Noordwijk 2006, ISBN 92-9092-453-5
Web links
- EGNOS portal page of the EU
- EGNOS info pages of ESA (English, technical details as of 2006, plus glossy newsletter)
Individual evidence
- ↑ https://www.golem.de/news/satellitennavigation-neuer-broadcom-chip-macht-ortung-per-mobilgeraet-viel-genauer-1709-130203.html Golem.de - New Broadcom chip makes location via mobile device much more accurate
- ↑ https://spectrum.ieee.org/tech-talk/semiconductors/design/superaccurate-gps-chips-coming-to-smartphones-in-2018 Spectrum.IEEE.org - Superaccurate GPS Chips Coming to Smartphones in 2018
- ↑ https://www.nsl-gnss.com/about-nsl/nsl-blog/15-products-and-services/55-xiaomi-mi8 NSL - Initial Tests of the Xiaomi MI 8 Dual Frequency GNSS Smartphone
- ↑ https://www.nsl-gnss.com/about-nsl/nsl-blog/15-products-and-services/56-xiaomi-mi8-2 NSL - Data Quality from the Dual Frequency Xiaomi MI 8
- ↑ EGSA: EGNOS system .
- ^ Javad Navigation Systems. Retrieved May 29, 2019 .
- ↑ Modification for broadband reception (satellites of several systems)
- ↑ EGNOS SERVICE NOTICE No. 015 (Rev. 2.1, August 31, 2018)
- ↑ SISNeT (PDF; 216 kB)
- ↑ EGNOS Message Server
- ↑ EGNOS Data Access Service, EDAS details
- ↑ EGNOS's integrity mechanisms for safety-of-life applications ( Memento from August 6, 2016 in the Internet Archive )
- ↑ Commission launches EGNOS Open Service - free access for citizens and companies
- ↑ EU Commission: Status of EGNOS SoL introduction - 9 September 2010 ( Memento from 9 March 2012 in the Internet Archive ) (PDF; 12 kB)
- ↑ ESSP News: Status on the EGNOS Safety-of-Life Service Introduction
- ↑ DFS press release ( Memento from June 3, 2012 in the Internet Archive )
- ↑ https://www.gsa.europa.eu/sites/default/files/brochure_sol-sept_2016.pdf EGNOS Safety of Life (SoL) - Service Definition Document
- ↑ https://www.gps.gov/systems/gps/modernization/civilsignals/ GPS.gov - New Civil Signals
- ↑ https://gssc.esa.int/navipedia/index.php/EGNOS_Future_and_Evolutions EGNOS Future and Evolutions
- ↑ http://europa.eu/rapid/press-release_IP-13-1129_de.htm
- ↑ http://insidegnss.com/gsa-eutelsat-contract-marks-major-milestone-for-egnos-v3/ InsideGNSS.com - GSA, Eutelsat Contract Marks Major Milestone for EGNOS V3
- ↑ https://gssc.esa.int/navipedia/index.php/EGNOS_Future_and_Evolutions EGNOS Future and Evolutions
- ↑ Airbus press release
- ^ European Satellite Services Provider. Retrieved May 29, 2019 .
Global Systems
Historically:
Transit ·
Parus / Zikada
In operation:
GPS ·
GLONASS ·
Galileo ·
BeiDou-2
Regional systems or regional supplementary systems
Historically:
BeiDou-1
Under construction:
QZSS ·
IRNSS 
Supporting satellite-based systems ( SBAS )
In operation:
WAAS ·
MSAS ·
EGNOS
Under construction:
GAGAN ·
QZSS-SAIF ·
SDKM
See also list of navigation satellites