The European GNSS Agency (GSA) has officially launched the equipment for dual frequency Galileo, GPS and EGNOS project (EDG²E) with a consortium led by Thales. The four-year project intends to develop a dual-frequency multi-constellation receiver, enabling enhanced navigation capabilities, support standardization and certification preparation, and facilitate the expected increase in air traffic, both in Europe and globally.
The prototype EDG²E receiver use GPS and Galileo signals as well as those from the European SBAS multi-constellation EGNOS. The project aims to achieve a prototype demonstration by 2021. At the end of the EDG²E project, the first SBAS dual-frequency GPS+Galileo receivers for aviation will be ready for final development and use in the aviation sector and in other safety-critical applications. Fully achieved receivers are foreseen to be installed in commercial aircraft by 2025.
EGNOS, certified for use in aviation since February 2011, is developing its own next generation, called EGNOS V3, to further enhance performance by complementing both the EU Galileo and the US GPS satellite navigation constellations.
“EGNOS v3 will provide aviation users with an increased quality of services, better accuracy and extended coverage area among other key performance indicators” said Jean-Marc Pieplu, GSA head of the EGNOS Services Programme. “Fundamental Element Programme is a medium that supports development of terminals and antennae fostering use of E-GNSS in all domains. In this perspective,EDG²E is an important step for GSA as it will contribute to availability of high technology products on the aviation market, taking benefit of Dual Frequency Multi Constellation feature offered by EGNOS v3.”
The consortium includes Thales, Thales Alenia Space and ATR, as well as contributions from Dassault Aviation and the French Civil Aviation Authority.
Feature image courtesy of the European Space Agency (ESA).
The next generation of Europe’s satellite navigation overlay service, EGNOS, will combine use of GPS and Galileo signals to improve accuracy and robustness of navigation for air traffic and other uses where lives are at stake.
A contract was signed Jan. 26 at ESA’s technical centre in the Netherlands for the second generation of the European Geostationary Navigation Overlay Service, EGNOS V3, planned to enter service in 2025.
ESA Director of Navigation Paul Verhoef signs the EGNOS V3 contract Jan. 26 with Senior Vice President of Airbus Defence and Space, Mathilde Royer Germain. (Photo: ESA)
ESA Director of Navigation Paul Verhoef signed the contract with the senior vice president of Airbus Defence and Space, Mathilde Royer Germain, in the presence of senior managers of the European Global Navigation Satellite System Agency (GSA) and of the European Commission.
This improved version of the service will take advantage of in-operation Galileo signals as well as new frequencies from an improved class of GPS satellites. Use of the L5 second frequency will improve service robustness against errors and propagation delays caused by the ionosphere, an electrically active outer layer of Earth’s atmosphere.
“This will be the first such regional satellite augmentation systems worldwide to employ dual frequency, GPS and Galileo signals,” comments Didier Flament, overseeing EGNOS development for ESA.
For aircraft with the latest avionics, EGNOS V3 will be able to guide them accurately and safely down to Category 1, a 10 m Vertical Alert Limit (also called Cat1 Autoland capability), while also providing legacy users equipped with current avionics a more robust version of the current LPV200, or 35 m vertical limit vertical guidance service.
As well as improving services for civil aviation, the plan is to introduce new services for other sectors such as maritime navigation and rail, and extend service coverage from the European continent to link up seamlessly with other interoperable augmentation systems worldwide.
EGNOS is Europe’s other satellite navigation system, next to the global Galileo system. Comparable to the US WAAS, the Wide Area Augmentation System, and other regional augmentation systems in the rest of the world, EGNOS is an overlay system based on a network of ground stations and transponders on geostationary satellites. These stations gather data on the current accuracy of US GPS signals and embed correction data in the EGNOS signal, which is uplinked via geostationary satellites to EGNOS users.
The current EGNOS augments the accuracy of GPS signals across Europe and informs users of their current reliability level within six seconds. EGNOS belongs to a family of systems called Satellite Based Augmentation Systems (SBAS); the EGNOS V3 second generation will augment both GPS and Galileo.
Designed against global standards set by the International Civil Aviation Organisation, EGNOS began offering its Open Service for non-safety-of-life uses in October 2009. In March 2011 its Safety-of-Life Service became available for aircraft navigation.
Dozens of European airports are today employing EGNOS for vertical guidance approaches, as an economic alternative to ground-based infrastructure, like Instrument Landing Systems. It is estimated that that around 110 000 aircrafts worldwide are today equipped and using SBAS systems.
The development of satellite-based augmentation systems around the world is being coordinated in particular by the international SBAS Interoperability Working Group, which last week held its 33rd meeting at ESA’s centre in Madrid, chaired by ESA and the US Federal Avigation Authority, joined by current or planned service providers from Africa, Australia, Canada, China, India, Japan, Russia and South Korea.
Initiated by ESA in cooperation with the EU and Eurocontrol, the EGNOS Exploitation phase is managed by GSA and funded by the EU. ESA manages the EGNOS development under a working arrangement signed between GSA and ESA.
EGNOS V3 will offer improved and secure Civil Aviation Safety of Life services for the next decade over Europe. The program will ensure a full continuity of service and will be the first operational SBAS using both GPS and Galileo.
Airbus has been selected by the European Space Agency (ESA) as the prime contractor to develop EGNOS V3, the next generation of the European Satellite Based Augmentation System (SBAS) planned to provide the civil aviation community with advanced safety-of-life services and new services to maritime and land users.
Developed by ESA on behalf of the European Commission and the European GNSS Agency (GSA), EGNOS V3 (European Geostationary Navigation Overlay Service) will provide augmented operational safety-of-life services over Europe that improve the accuracy and availability of user positioning services from existing GNSS (Galileo and GPS).
EGNOS also provides crucial integrity messages to EGNOS users with alerts within a few seconds in case of system degradation, consolidating EGNOS’ position as one of the leading edge GNSS systems in the future.
Besides improved safety-of-life services, EGNOS V3 will improve robustness against increasing security risk, in particular cyber-security risks.
EGNOS V3 will ensure a full continuity of service for the next decade and will be the first operational SBAS implementing the dual-frequency and multi-constellation world standard, with both GPS and Galileo, replacing EGNOS V2 which has been in operation since 2011.
“This programme is strategic for Airbus to strengthen our position in the Navigation field. The signature of this contract is the result of more than 5 years of intense team work and investment,” said Nicolas Chamussy, head of Space Systems at Airbus. “With our consortium, we bring a large pool of resources and experience in Europe covering the successful development of critical and secure ground segment. I am confident that we will make EGNOS V3 a success story.”
As prime contractor, Airbus will be leading a consortium with partners from France, Germany, Spain and Switzerland. Airbus will be responsible for the development, integration, deployment and preparation of EGNOS V3 operations, the overall performance of the system and the Central Processing Facility, which is the heart of the real-time navigation algorithms.
During the 6.5-year contract, around 100 people and 20 subcontractors will work on delivering the EGNOS V3 system. In 2023, the single-frequency version will be available to replace the current operational version and, 18 months later, the final version in dual frequency will be delivered.
EGNOS is composed of a large network of about 50 ground stations deployed over Europe, Africa and North America, two master control centers near Rome and Madrid, and a System Operation Support Centre in Toulouse. EGNOS will also use geostationary satellite navigation payloads.
By Paul Verhoef
Director of the Galileo Programme and Navigation-related Activities,
European Space Agency
Paul Verhoef, director of the Galileo Programme. (Photo: ESA)
The European Space Agency (ESA) and the European GNSS Agency (GSA) are starting 2018 with the commissioning and In-Orbit Testing (IOT) of four new Galileo satellites.
This work is fairly routine for us as we have achieved the process successfully many times. But the impact of four new satellites for Galileo services is a different story.
This batch of satellites provided by OHB of Germany — 19, 20, 21 and 22 — will bring our constellation to 22 satellites. Together with the necessary ground segment delivered by Thales Alenia Space (TAS) and Airbus Defense and Space (ADS) and their many subcontractors throughout Europe, this will be providing availability to users anywhere in the world in order to achieve a high-quality position solution 99.8% of the time. “High quality” is hereby meant that the position dilution of precision (PDOP) will be smaller than 5, with our final accuracy for a full 24 FOC satellites operating at full potential being PDOP ~ 2.4.
This achievement will create a step change in the ability of service providers and equipment manufacturers to utilize the Galileo service. For all intents and purposes, it means the Galileo signal can always be relied upon to be there, and industry can sell products and design the power budget of devices based upon that fact.
Dual Frequency. The first mass-market GNSS receiver chip for smartphones and mobile devices that is able to utilize dual-frequency Galileo signals was released by Broadcom in September, able to employ both L1/E1 and L5/E5 signals. In 2018, dual-frequency technology like this will provide an order of magnitude increase in the performance of mobile device location-based services (LBS), especially in urban environments, and Broadcom advertises a 50% reduction in power consumption. The world of mobile-device LBS is going to change in 2018, and it will be due to the availability of Galileo.
It will not be the first time the partnership of ESA, the European Commission (EC) and the GSA has made a service available that has changed the nature of the marketplace. The GSA already has in service the ESA-designed EGNOS LPV200 aircraft approach service performing so well that countries like France have taken the decision to phase out the terrestrial Instrument Landing System that has burdened the capital expenditure budgets of airports in the past.
We have had discussions with several commercial organizations that are interested in building products around Galileo, and I am excited to see what they are going to come up with. With Galileo Initial Services the world had a new navigation signal to study and trial. In 2018 the world will have a new star to navigate by — well, a new constellation of 22 to 24 stars, I should say!
FOC. In the summer of 2018 we will launch the final part of the Galileo FOC constellation (geometrically speaking) with four more satellites taking us beyond the 24 needed for 100% coverage and minimum performance limitation from satellite geometry. The launch will also provide our first in-orbit spares, enabling us to plan for the end of life of our old validation phase satellites or otherwise supplement the constellation to improve performance.
What might we do with these in-orbit spares? Our first priority is to complete a constellation of 24 satellites in the correct orbits for minimum PDOP; as you know, a Fregat upper-stage malfunction left GSAT 0201 and 0202 in orbits too elliptical to correct fully, so the current plan is to complete the 24-satellite geometry. 0201 and 0202 are foreseen to be fully integrated in the Galileo operational system in 2018 following further testing and preparations, allowing us to have a 24+2 constellation with “hot back-up” from 0201 and 0202 contributing at around current GPS satellite levels of accuracy.
“It will not be the first — nor the last — time the partnership of ESA, the EC and the GSA has made a service available that has changed the nature of the marketplace.”
Of course, as is known to the community, the validation-phase satellite GSAT 0104 is down to single frequency, and we routinely monitor the health of all satellites. 0104 is the only satellite that has lost part of its function; designed-in redundancy has managed all other problems.
However, obviously we will be examining all options for deployment to ensure that the Galileo schedule is not impacted by in-orbit failures, and those we have experienced we have learned from and mitigated successfully without impacting the service.
The first two spares are not the end of our ability to maintain the constellation and our system performance. All four validation phase satellites will need to be replaced, and so the “Batch 3” satellite procurement will continue to regularly roll out satellites for replenishment of the constellation.
Enhancements. That won’t mean we will be resting on our laurels. In 2018 we also plan to release enhancements to the ground segment for Galileo, a process that will be a first as the system is already being operated by the GSA.
The process of managing an in-service upgrade program with the GSA is going to be new and challenging, but we have a strong engineering support team deployed as part of our working arrangement with the GSA to help ensure the process goes smoothly.
Of course, the need for GSA to be able to continue smooth operations imposes extra discipline and imposes on us a balance between stable operations and continued build-out of the infrastructure. We do not consider this to be a problem; on the contrary, the focus will be on robust operations and availability to the user.
Back at base (ESTEC in the Netherlands for Galileo and Toulouse, France, for EGNOS) we are full steam ahead on preparing the future. We are moving forward at considerable pace with our next-generation designs that develop new functionality for continuous service improvements.
Free PPP. Galileo was designed to broadcast a Commercial Service signal providing services such as precise point positioning to paying customers, but we are pleased to able to report that the EC has confirmed that this service will be provided for free by the European Union. In 2018/2019 the GSA will select the providers and get that unique, free service on the air.
In 2017 the EC confirmed the decision to implement the commercial service using E6-B with both encrypted and open components so all users could benefit for all frequency bands. Now, with the decision to make the service available free of charge, all users of Galileo, with the right type of receiver, will be able to achieve position fixes with an accuracy around 10 cm from Galileo’s first-generation constellation by 2020/2021.
The Galileo Public Regulated Service will also be a focus, with the EC soon to decide upon release dates for the first milestones on the service roadmap. The infrastructure and equipment to support a secure service is being put in place, and I can’t say more for security!
The next generation of European GNSS technology will include multi-constellation EGNOS, Galileo 2nd Generation (G2G) and a transition batch of satellites between the first and second generations to get the best technology proven in flight and working for Galileo users as soon as possible. G2G will reach its System Requirements Review stage in the first half of 2019. To be ready for that we are looking at:
clock technology and ensembles
inter satellite links
propulsion technology
flexible payloads and power allocation
5G telecoms networks standards and what we need to do ensure we provide the timing services those networks will need and new signals with time to first fix (TTFF) and power requirements for acquisition of signal that are compatible with 5G devices. Look out for a new pilot signal E1-D to move forward on this.
Open Service authentication and support for ARAIM (Advanced Receiver Autonomous Integrity Monitoring).
Finally, 2018 will see the first contract awards of the Navigation Innovation Support Programme. This is a programme specifically designed to encourage R&D, new concepts and new products and to ensure that 2018 is not the last time ESA with the EC and its industrial partners deploy a GNSS service for GSA to operate that changes the world.
A Belgian container terminal is about to become Europe’s largest, and GNSS technoloy will be integrated.
The MSC PSA European Terminal (MPET) in Antwerp, Belgium, is moving its operations from the Delwaidedock on the right bank of the river Schelde to the Deurganckdock on the left bank.
The move is part of an expansion of its capacity of 9 million TEUs annually. TEUs are a 20-foot equivalent unit, a term used to describe the capacity of container ships and container terminals.
When fully moved and operational, the left bank terminal will feature a total of 41 quay cranes across 10 berths, 200 straddle carriers and a quay length of 3,550 meters.
“For this project, we were looking for a positioning solution that was compatible with the solution that has been in use on the terminal since 2008,” said Douwe Witteveen, senior project manager at PSA MPET. “We need to accurately know where every container is picked up and dropped off without interfering with the actions of the driver. “Based on sensors in the vehicle, the GNSS unit must detect a pick-up or drop-off and provide a position to our system. Unfortunately, the receivers used previously were no longer available, so we needed to find someone who could make a new custom integration fast.”
Multipath mitigation copes with GNSS reflections caused by metal cargo containers. (Photo: Airobot)
Airobot was selected by MPET to create a solution, and did so in less than four months, said Jan Leyssens, managing director at Airobot.
The SC-PSA-GNSS unit integrates the AsteRx-m GNSS receiver from Septentrio NV and uses EGNOS to provide submeter accurate positions. The receiver has multipath mitigation technology on board to cope with the many GNSS reflections caused by all the metal containers, and combines GPS and GLONASS to provide a solution close to the quay cranes.
“We started discussions about the requirements in January and have delivered 100 units in less than four months’ time,” Leyssens said. “Fortunately, we have a lot of experience integrating GNSS technology into our drone solutions, so we could act fast. We also listened to the people in the field to make sure the unit is easy to install and existing cable installations could be used.”
“We believed that the know-how and expertise of the Airobot team could help us to get a solution fast, and they delivered what they promised,” said Douwe.
We examine the performance of EGNOS in Finland, which lies near the northeast periphery of the coverage area, and how this performance can be improved now and in the future.
By Mohammad Zahidul H. Bhuiyan, Heidi Kuusniemi, Auryn Soderini, Salomon Honkala and Simo Marila
INNOVATION INSIGHTS with Richard Langley
“[O]NE ORBIT, WITH A RADIUS OF 42,000 KM, has a period of exactly 24 hours. A body in such an orbit, if its plane coincided with that of the earth’s equator, would revolve with the earth and would thus be stationary above the same spot on the planet. … [A] transmission received from any point on the hemisphere could be broadcast to the whole of the visible face of the globe, and thus the requirements of all possible services would be met.” So wrote writer and futurist Arthur C. Clarke in his October 1945 Wireless World article “Extra-terrestrial Relays: Can Rocket Stations Give World-wide Radio Coverage?,” envisaging the geostationary orbit (GEO) communication satellite.
The first GEO satellite was Syncom III, orbited by the United States in August 1964. Since then, more than 1,000 satellites have been launched into what is known as the Clarke Belt and around 450 are presently active. Most of them are used for civil or military communication. Some are used for direct-to-user TV and radio. Some are used for weather monitoring and other kinds of surveillance. And some are used for augmenting GPS.
While GPS is a remarkable positioning system, its real-time accuracy using L1-frequency pseudorange measurements and its instantaneous integrity are not sufficient for some applications such as aircraft navigation. That is why the U.S. Federal Aviation Administration developed the Wide Area Augmentation System (WAAS), the first satellite-based augmentation system (SBAS). WAAS provides differential correction data and integrity information to GPS users in real time throughout most of North America using a “bent pipe” from a ground station through the GEO satellite to a user’s equipment. It uses a state-space-domain correction approach, which provides corrections for the satellite orbit and clock data transmitted by GPS satellites along with ionospheric propagation delays, all computed from measurements collected by a continent-wide tracking network.
The WAAS concept has been duplicated for other regions. Three other SBASs are in full operation: the European Geostationary Navigation Overlay Service (EGNOS), Japan’s Multifunctional Transport Satellite Satellite-based Augmentation System, and India’s GPS-aided GEO Augmented Navigation System. Russia’s System for Differential Correction and Monitoring is currently in development.
One hitch with GEO satellites whatever their function is their inability to service high latitudes well. At a latitude of 65°, a GEO satellite has an elevation angle of only around 17° at most and at 75°, it’s about 6° or less. Even if a GEO satellite is above the local horizon, communication might be difficult due to the longer signal path length between the satellite and the user.
And so it is with GEO satellites used for SBAS at high latitudes. And there is an additional problem that even if the signals from an SBAS satellite can be received, corrections for some GPS satellites will not be received if they are outside the coverage area of the SBAS tracking network. In this month’s column, we examine the performance of EGNOS in Finland, which lies near the northeast periphery of the EGNOS coverage area, and how this performance can be improved now and in the future.
FIGURE 1. Finnish national GNSS network, FinnRef. The three stations highlighted in red had the worst positioning accuracy in our analyses.
The European Geostationary Navigation Overlay Service (EGNOS) is the first European-operated satellite navigation system and is a precursor to Galileo, Europe’s independent global navigation satellite system (GNSS), now being deployed. EGNOS, as a satellite-based augmentation system (SBAS) similar to the U.S. Wide Area Augmentation System (WAAS), was developed with the vision to improve the performance of GNSSs, such as GPS and Galileo. At the moment, EGNOS only augments GPS, making it suitable for safety-critical applications such as flying aircraft or navigating ships through narrow channels.
Additionally, EGNOS also supports new applications in many different sectors, such as agriculture (for high-precision spraying of fertilizers), transport (enabling automatic road-tolling or pay-per-use insurance schemes) or even precise personal navigation services for general and specific use.
At present, there are two operational geostationary Earth orbiting (GEO) satellites and until March 2017, these satellites had pseudorandom noise code (PRN) numbers 120 and 136 that simultaneously broadcast EGNOS correction messages to European GPS users. The PRN satellites 120 and 136 are located at 15.5°W and 5.0°E. (Since March, PRN 123 has replaced PRN 136 as one of the operational EGNOS satellites.) The use of EGNOS in the northern Europe is much more challenging than elsewhere in Europe due to the relatively low-elevation angle of some EGNOS satellites as seen from there of about 14° or less.
To improve our understanding of the true performance of EGNOS in Finnish territory, we recently carried out a project entitled “Finland’s EGNOS Monitoring and Performance Evaluation (FEGNOS).” At the northeastern edge of the EGNOS coverage area, the availability of the EGNOS geostationary satellites is compromised due to their low-elevation angles. The Finnish Geospatial Research Institute (FGI) at the National Land Survey of Finland (NLS) maintains a network of 20 permanent GNSS reference stations (FinnRef) all over Finland. The core objective of the FEGNOS project is to evaluate the performance of EGNOS at all of those reference stations to determine if the EGNOS system performance reaches its target in Finland.
Building on our initial research, in this article we report on the analysis of EGNOS performance at all 20 FinnRef stations for a year-long time-frame from November 2015 until October 2016. As it is of importance to compare the performance of EGNOS in a geographic region where EGNOS satellite visibility can be poor due to low-elevation angle, we assessed the performance of EGNOS by comparing the receivers’ own decoded SBAS messages against the SBAS messages provided by the EGNOS Data Access Service (EDAS). The daily EDAS SBAS messages can be freely downloaded from the EDAS server with prior authentication from EDAS. The performance analysis has been carried out for the following three cases:
Applying EGNOS corrections obtained from the EDAS server
Applying EGNOS corrections obtained from the receiver-decoded (Rx-decoded) EGNOS messages
GPS stand-alone solution without any EGNOS corrections.
We carried out the data analysis using the EGNOS analyzing tool called PEGASUS (which originally stood for Prototype EGNOS Analysis Using SAPPHIRE, where SAPPHIRE stands for Satellite and Aircraft Database Programme for System Integrity Research) from Eurocontrol. The results show that the Rx-decoded EGNOS performance is not as good as the performance obtained from the EDAS-offered message corrections. The ongoing experience and knowledge learned from the project has helped to identify weaknesses of the EGNOS system at high northern latitudes.
FINNISH NATIONAL GNSS NETWORK, FINNREF
The Finnish National GNSS network, FinnRef, was established on the initiative of the Nordic Geodetic Commission and the director generals of the Nordic Mapping Authorities in the 1990s. FinnRef is part of the Nordic GNSS network, and some stations of the FinnRef network also contribute to the global International GNSS Service (IGS) network and to the European Permanent Network (EPN). The primary function of FinnRef is to offer geodetic-grade GNSS measurements, which have been continuously used for forming and maintaining the national coordinate system (EUREF-FIN). In addition, the FinnRef network is used for many GNSS-related research activities. For example, it is now possible to analyze the positioning performance of different augmentation services via the FinnRef network. Currently, FinnRef also offers an open positioning service based on the differential GNSS (DGNSS) corrections for GPS and GLONASS.
The FinnRef network was renewed during the 2012–2013 timeframe. The renewed FinnRef network now consists of 20 GNSS reference stations, as shown in FIGURE 1. The raw GNSS data from all 20 reference stations is used in the FEGNOS project for EGNOS performance monitoring and analysis.
DATA COLLECTION
EGNOS signal monitoring at all FinnRef stations was carried out for one year from Nov. 4, 2015, until Oct. 31, 2016. There are in total about 360 days of data from the 20 stations out of a possible 366 days (2016 was a leap year). The day-of-year (DOY) information for the collected data set is detailed in TABLE 1. No data was available during DOY 233 and 234 of 2016 due to a technical fault at the FinnRef stations. There are 57 days of data from the year 2015 and 303 days of data from 2016.
Table 1. DOY information for the year-long data set.
Each FinnRef station is equipped with a dual-frequency geodetic-grade receiver. Each receiver generates 1-hour binary proprietary data files with a 1-Hz data rate. Data is pushed to the network server and saved at the conclusion of each hour. This means that there are in total 24 data sets for each single day for one single station. All the stations’ binary data files are then organized under one directory, which is named after DOY for that particular year. The FEGNOS data Collection Tool (FEGCoT) was developed in Matlab to collect data every day automatically from all 20 FinnRef stations.
These three steps are followed for automatic data collection:
Collect: 1-Hz hourly data is collected from the FinnRef server, and then saved to the local hard disk for further processing.
Convert: The saved raw binary-formatted hourly data files from the receivers are converted to RINEX observation, navigation and SBAS data files via the receiver manufacturer’s converter.
Combine: In this step, all 24 one-hour data sets from each station are combined into one single 24-hour data set for every RINEX file type (that is, observation, navigation and SBAS files).
The combined 24-hour RINEX data file for each station is then processed using the PEGASUS software. The key configuration parameters used in the data analysis are listed in TABLE 2. (Note that airborne accuracy designator refers to specifications in the WAAS Minimum Operational Performance Standards, MOPS.)
TABLE 2. PEGASUS configuration parameters.
Two PEGASUS modules are used for data analysis:
Convertor module: The Convertor module translates the RINEX observation, navigation and SBAS data into a generic format, which can then be used by the GNSS_Solution module for detailed analysis. Convertor can also use input from different GNSS/SBAS receivers and then transform the recorded binary data into readable ASCII data.
GNSS_Solution module: The GNSS_Solution module is used to compute a position solution in conformance with the MOPS for GNSS receivers used in avionics (GPS, SBAS or ground-based augmentation systems). In other words, the GNSS_Solution module can be considered as a post-processing MOPS-compliant GNSS receiver. It interfaces with other PEGASUS components, notably the Convertor module.
The elevation cut-off angle and the minimum accepted signal-to-noise ratio are kept low so as to have more satellites available for user-position computation. (The European Global Navigation Satellite Systems Agency (GSA) advises that range measurements from EGNOS satellites not be used for position computation.)
A Matlab-script was written to download EDAS-provided daily SBAS messages automatically from the EDAS server. All the PEGASUS-related processing was also executed by a Matlab-based script.
ANALYSIS OF RESULTS
We analyzed the EGNOS/GPS performance for the above-mentioned cases with the collected year-long data set from the 20 FinnRef stations. The operational time or uptime of each FinnRef station was monitored throughout the FinnRef network nodes on a daily basis. The average uptime of each station for the one-year data set is shown in FIGURE 2. The “b” in station names indicates one of the two data streams available from each station. The figure shows that most of the stations were up for more than 98% of the time, while only few have uptimes close to 95%.
FIGURE 2. Station uptime for all FinnRef stations for the year-long data set.
According to EGNOS Open Service (OS) horizontal and vertical accuracy requirements, the 95% Horizontal Navigation System Error (HNSE) should be less than 3 meters, and the 95% Vertical Navigation System Error (VNSE) should be less than 4 meters in the EGNOS service provision area. The horizontal and vertical position errors at a defined time epoch are computed as the difference between the estimated navigation position and the actual position in horizontal and vertical planes, respectively. The HNSE (95%) and VNSE (95%) were computed for all FinnRef stations with the year-long data set.
The yearly EGNOS performance in terms of HNSE (95%) and VNSE (95%) are shown in FIGURES 3 and 4, respectively. It can be observed that GPS+EGNOS offers significant accuracy improvement compared to GPS stand-alone solutions for all of the stations. Vertical accuracy improvement for EGNOS is greater than the horizontal improvement, mostly due to the better mitigation of ionospheric error compared to stand-alone GPS. We also observed that the Rx-decoded EGNOS performance is not as good as the performance when corrections are obtained from the EDAS server. This might be due to the poor visibility of the EGNOS satellites at northeastern latitudes, which resulted in data aging or partial data loss of EGNOS messages.
FIGURE 3. HNSE (95%) for all FinnRef stations.FIGURE 4. VNSE (95%) for all FinnRef stations.
In FIGURES 5 and 6, the daily EGNOS performance in terms of VNSE (95%) are shown for the two cases: 1) applying EGNOS corrections from EDAS-provided EGNOS messages, and 2) applying EGNOS corrections from Rx-decoded EGNOS messages, respectively.
FIGURE 5. VNSE (95%) performance over time with GPS+EGNOS (EDAS) corrections.FIGURE 6. VNSE (95%) performance over time with GPS+EGNOS (Rx-decoded) corrections.
For a better understanding, the percentage of EGNOS OS requirement failure when analyzed on a daily basis with EDAS offered corrections is presented in FIGURE 7.
FIGURE 7. Percent of EGNOS OS requirement failure with EDAS-provided EGNOS correction messages.
The percentage of EGNOS OS requirement failure was computed from the number of days where the HNSE (95%) ≥3 meters in the case of horizontal navigation solution error and VNSE (95%) ≥ 4 meters in the case of vertical navigation solution error. As observed from Figures 5 and 7, the EDAS offered EGNOS corrections fail to meet the OS requirement only in a few instances. Similarly, the percentage of EGNOS OS requirement failure when analyzed on a daily basis with Rx-decoded corrections is presented in FIGURE 8. It can be easily seen from Figures 6 and 8 that the Rx-decoded EGNOS performance fails to meet the OS requirement in many instances. However, the daily fluctuations are averaged out when the year-long data is taken into account, providing satisfactory performance on the whole.
FIGURE 8. Percent of EGNOS OS requirement failure with Rx-Decoded EGNOS correction messages.
The yearly EGNOS performance in terms of VNSE (99%) is shown in FIGURE 9.
FIGURE 9. Sorted VNSE (99%) performance with GPS+EGNOS (EDAS) corrections for all FinnRef stations.
The three stations with the worst accuracy are highlighted in red in Figure 1. These stations are located on the northeastern border of the EGNOS coverage area. The EGNOS User Differential Range Error Indicator (UDREI) figure for three stations (FINb, VIRb, and SAVb) is shown in FIGURE 10(a), 10(b) and 10(c), respectively.
FIGURE 10. EGNOS UDREI as seen at (a) FINb, (b) VIRb and (c) SAVb.
The stations were chosen so that they represent a wide geographical spread over Finland. According to Figure 10, the satellite UDREI values are in the range of 14 and 15 (marked as blue) at the northeastern edge of the sky plot. A UDREI of 14 indicates “not monitored” and 15 indicates “do not use” for a particular satellite. Even though the satellites had a moderate elevation angle with respect to the user, the EGNOS system was unable to offer corrections to those satellites in the northeastern sky. Relatively lower availability of GPS satellites coupled with the lower number of EGNOS Ranging and Integrity Monitoring Stations (RIMS) at northeastern latitudes contributed to the poorer than expected positioning performance in the northeastern coverage area of EGNOS.
CONCLUSIONS
In this article, we presented a summary of an analysis of EGNOS in Finland for a year-long period, and we explained our automated data collection and data analysis procedure. The following key observations can be made based on the analysis of the year-long data set:
The use of EGNOS significantly improves the positioning performance compared to GPS stand-alone operation.
The vertical accuracy improvement for EGNOS is higher than the horizontal improvement compared to GPS stand-alone performance.
The performance of EGNOS with the receivers’ own decoded message corrections is not as good as the performance obtained through EDAS-provided EGNOS corrections.
EGNOS does not offer corrections for those GPS satellites that are setting in the northeastern sky of the EGNOS coverage area.
The percentage of EGNOS OS requirement failure when analyzed on a daily basis with Rx-decoded corrections is significant. This is mostly due to the poor visibility of GEO satellites from northeastern latitudes.
These findings emphasize the fact that there is a great need at northeastern latitudes for an alternative solution to the GEO satellites broadcasting EGNOS corrections. The existing alternative solution is to download the corrections from the Internet through EDAS at the cost of an additional communication link. The other possible alternative could be to broadcast corrections via inclined geosynchronous orbit satellites, or by some other means.
ACKNOWLEDGMENTS
This article is based on the paper “Performance of EGNOS in North-East European Latitudes” presented at the 2017 International Technical Meeting of The Institute of Navigation held Jan. 30–Feb. 1, 2017, in Monterey, California. The research was conducted within the FEGNOS project, funded by the Finnish Transport Agency and the Finnish Geospatial Research Institute at the National Land Survey of Finland. More information about the FEGNOS project can be found at www.fegnos.net.
MANUFACTURER
The receivers in the FinnRef network are JAVAD GNSS Inc. Delta-G3Ts and the antennas are JAVAD RingAnt_DMs with SCIS radomes.
MOHAMMAD ZAHIDUL H. BHUIYAN received his Ph.D. degree in 2011 from the Department of Electronics and Communications Engineering, Tampere University of Technology, Finland. He is a research manager in the Department of Navigation and Positioning at the Finnish Geospatial Research Institute (FGI) of the National Land Survey of Finland in Kirkkonummi. He is also the acting deputy head of the institute’s Satellite and Radio Navigation Research Group.
HEIDI KUUSNIEMI is the director of FGI’s Department of Navigation and Positioning. She is also an adjunct professor in the Department of Built Environment at Aalto University in Espoo and in the Department of Electronics and Communications Engineering at Tampere University of Technology. She is also the current president of the Nordic Institute of Navigation. She received her M.Sc. and D.Sc.(Tech.) degrees from Tampere University of Technology in 2002 and 2005, respectively.
AURYN SODERINI is an M.Sc. student in the Department of Electronics and Communication Engineering at Tampere University of Technology. He received his B.Sc. in 2012 from the Department of Electronics Engineering at The Third University of Rome.
SALOMON HONKALA is a researcher at FGI. He holds an M.Sc. (Tech.) degree in electrical engineering from Aalto University.
SIMO MARILA is a research scientist in FGI’s Department of Geodesy and Geodynamics. He received an M.Sc. degree in 2011 from Aalto University.
FURTHER READING
• Authors’ Conference Paper
“Performance of EGNOS in North-East European Latitudes” by M.Z.H. Bhuiyan, H. Kuusniemi, A. Soderini, S. Honkala and S. Marila in Proceedings of the 2017 International Technical Meeting of The Institute of Navigation, Monterey, California, Jan. 30–Feb. 1, 2017, pp. 627–636.
• Authors’ Related Work
“Performance Comparison of Differential GNSS, EGNOS and SDCM in Different User Scenarios in Finland” by S. Marila, M.Z.H. Bhuiyan, J. Kuokkanen, H. Koivula and H. Kuusniemi in Proceedings of ENC 2016, European Navigation Conference 2016, Helsinki, Finland, May 30–June 2, 2016, doi: 10.1109/EURONAV.2016.7530550.
“Low-Cost Precise Positioning Using a National GNSS Network” by M. Kirkko-Jaakkola, S. Söderholm, S. Honkala, H. Koivula, S. Nyberg and H. Kuusniemi in Proceedings of ION GNSS+ 2015, the 28th International Technical Meeting of the Satellite Division of The Institute of Navigation, Tampa, Florida, Sept. 14–18, 2015, pp. 2570-2577.
“Finnish Permanent GNSS Network: From Dual-frequency GPS to Multi-satellite GNSS” by H. Koivula, J. Kuokkanen, S. Marila, T. Tenhunen, P. Häkli, U. Kallio, S. Nyberg and M. Poutanen, in Proceedings of UPINLBS 2012, the 2nd International Conference and Exhibition on Ubiquitous Positioning, Indoor Navigation and Location-Based Service, Helsinki, Finland, Oct. 3–4, 2012, doi: 10.1109/UPINLBS.2012.6409771.
• European Geostationary Navigation Overlay Service
EGNOS – the European Geostationary Navigation Overlay System – A Cornerstone of Galileo, edited by J. Ventura-Traveset and D. Flament, ESA SP-1303, European Space Agency, Noordwijk, The Netherlands, 2006.
• EGNOS Data Access Service
“EDAS (EGNOS Data Access Service): Differential GNSS Corrections for Land Applications” by J. Vázquez, E. Lacarra, M.A. Sánchez and Pedro Gómez in Proceedings of ION GNSS+ 2016, the 29th International Technical Meeting of the Satellite Division of The Institute of Navigation, Portland, Oregon, Sept. 12–16, 2016, pp. 3550–3561.
“Satellite Based Augmentation Systems” by T. Walter, Chapter 12 in Springer Handbook of Global Navigation Satellite Systems, edited by P.J.G. Teunissen and O. Montenbruck, published by Springer International Publishing AG, Cham, Switzerland, 2017.
Minimum Operational Performance Standards for Global Positioning/Satellite-Based Augmentation System Airborne Equipment, RTCA/DO-229E, prepared by SC-159, RTCA Inc., Washington, D.C., Dec. 15, 2016.
The European Space Agency (ESA) has signed a contract with Thales Alenia Space for an upgrade to Europe’s EGNOS satellite navigation augmentation system, which underpins the safety-critical use of satnav across Europe, according to ESA.
Designed by ESA and being exploited by Europe’s GNSS Agency (GSA), the European Geostationary Navigation Overlay Service (EGNOS) improves the precision of GPS signals over most European territory, while also providing continuous and reliable updates on the “integrity” of these GPS signals.
A network of ground monitoring stations throughout Europe performs an independent measurement of GPS signals, so that corrections can be calculated, and then passed to users immediately via a trio of geostationary satellites.
The result is that the EGNOS-augmented signals are guaranteed to meet the extremely high performance standards set out by the International Civil Aviation Organisation standard, adapted for Europe by Eurocontrol, the European Organisation for the Safety of Air Navigation.
Paul Verhoef, ESA director of the Galileo Program, and Philippe Blatt, VP Thales Alenia Space France, sign on June 6 a contract for an upgrade of EGNOS.
Paul Verhoef, ESA’s director of the Galileo programme and navigation-related activities, signed the contract at ESA Headquarters in Paris with Philippe Blatt, vice president of Thales Alenia Space France.
ESA is performing the procurement of EGNOS Version 2.4.2 under the overall program authority of the GSA, which oversees both EGNOS and Europe’s Galileo satellite navigation system.
Two upgraded EGNOS releases will be provided over the course of the development: EGNOS V2.4.2I and EGNOS V2.4.2A.
The releases will resolve various obsolescence issues related to EGNOS’s central processing facility, based in Toulouse, France — which generates the corrections and integrity information to be broadcast across the European continent — to ensure continuity of EGNOS services into the future, including safety-of-life services, to an ever-expanding community of users.
The new contract includes:
a refreshment and enhancement of the Central Processing Facility design without algorithm modification
an optimized qualification process
a guarantee of full compliance to safety-critical software development requirements
the performance of end-to-end verification activities extending to the three geostationary satellites used by the system
ensuring compliance to a new set of technical requirements and international standards.
Upgrades to the monitoring stations underpinning Europe’s EGNOS satnav augmentation system will support its evolution, said the European Space Agency.
The current 40 Ranging and Integrity Monitoring Stations (RIMS) sites across Europe and beyond are the bedrock of the European Geostationary Navigation Overlay Service (EGNOS), supplying highly accurate and robust satnav information that can be relied on for safety-critical purposes.
Thales EGNOS V3 RIMS rack.
Once a second, these stations gather raw satnav data to transmit information on signal quality and range measurements to the GPS satellites, allowing EGNOS to identify and remove any error in the signals.
The resulting corrections are then passed to users via a trio of geostationary satellites, delivering a several-fold increase in precision plus “integrity” — a guarantee of navigation service — for safety-of-life applications.
The result is that the EGNOS-augmented signals are guaranteed to meet the extremely high performance standards set out by the International Civil Aviation Organisation standard, adapted for Europe by Eurocontrol, the European Organisation for the Safety of Air Navigation.
The signals from space can therefore be relied on routinely for safety-critical tasks, such as vertically guiding aircraft during landing approaches.
“These current RIMS V2 stations have some inherent limitations, which we’ve sought to tackle in this upgraded V3 design,” said Didier Flament, ESA’s EGNOS programme manager.
Airbus EGNOS V3 RIMS rack.
“For instance, our current stations work only with GPS frequencies L1/L2 P(Y), while the future post-2020 EGNOS system will be operating on a multi-constellation basis, additionally employing modernized GPS signals, notably on both the L2 (L2C) and L5 frequency bands, as well as other signals from Galileo, on the similar E1 and E5 frequency bands.
“Our experience working with RIMS has emphasized the significance on performance of factors such as signal scintillation — caused by the ever-changing ionosphere, the electrically active layer of the upper atmosphere — as well as other environmental threats such as interference and multipath signal reflection.
“So this upgraded design increased robustness to these factors, based on more stringent development and operating standards, along with innovative radio-frequency environment monitoring.
“It also includes upgraded receiver technology to accurately monitor potential GPS and Galileo signal distortion — ‘evil waveform’ signal anomalies — in full compliance with international standards.”
The RIMS V3 stations will be based in the same or similar secure location as today’s stations — typically airports or space-based telecommunication sites.
Dual tracking antenna concept incorporated in EGNOS V3 RIMS design.
The individual RIMS antennas themselves can be relatively compact, about 50 cm high, with links to receiver and computing equipment.
Most of the RIMS V2 station antennas are currently surrounded by dedicated protection structures that limit the impact of interference and multipath local effects.
The European Global Navigation Satellite Systems Agency (GSA) has selected Eutelsat Communications for the development, integration and operation of the next-generation EGNOS payload on a future Eutelsat satellite.
Credit and copyright: GSA.
Eutelsat and GSA have concluded a long-term contract valued at €102 million covering the preparation and service provision phases for the EGNOS GEO-3 payload that will be hosted on the Eutelsat 5 West B satellite that is due for launch end of 2018.
The new payload marks a replenishment of current EGNOS capacity and is scheduled to start service in 2019 for a duration of 15 years.
With the addition of the EGNOS payload, Eutelsat is further optimizing the Eutelsat 5 West B satellite that was commissioned in October 2016 on a design-to-cost basis from Airbus Defence and Space and Orbital ATK. Airbus Defence and Space is building the satellite’s commercial Ku-band payload and the EGNOS payload while the platform is being manufactured by Orbital ATK.
The EGNOS GEO-3 payload on Eutelsat 5 West B will comprise two L-band transponders that will act as an augmentation, or overlay to GNSS messages. Data from GNSS measurements received by an interconnected ground network of positioning stations across Europe will be transferred to a central computing centre where differential corrections and integrity messages will be calculated and then broadcast by Eutelsat 5 West B to users.
The new payload will be the first step towards the deployment of the EGNOS next generation, EGNOS V3. This new generation of EGNOS will augment both Galileo and GPS and is planned to be qualified by 2022. EGNOS V3 will provide a higher level of performance and robustness than the current EGNOS legacy services, as required by the growing use and reliance on such services.
Established in 1977, Eutelsat Communications specializes in communications satellites. The company provides capacity on 39 satellites to clients that include broadcasters and broadcasting associations, pay-TV operators, video, data and internet service providers, enterprises and government agencies.
On March 20, PRN 123 (now in test) will be introduced in the operational platform, and on March 21, PRN 136 will be moved from the operational platform to the test platform.
Users equipped with non-(E)TSO-certified SBAS receivers (such as those used in agriculture, surveying, mapping and maritime, but not in aviation), it is recommended that users reassess the equipment configuration after the change, to ensure that both operational EGNOS GEO satellites (PRN 120 and PRN 123) are configured in the equipment.
More details on this change are available in the official Service Notice #15.
Depending on the receiver, users can check equipment manuals or contact product manufacturer/dealer. Guidance is provided on the EGNOS website on how to configure an EGNOS receiver for some of the most common equipment used in agriculture.
I write at an especially exciting moment for the Galileo satellite navigation system, as two flagship European programmes combine for the very first time.
Mid-November will see the very first Galileo launch using an Ariane 5 launcher from Europe’s Spaceport in French Guiana, in place of the Soyuz that has served the constellation up until now. Four instead of two Galileo satellites will be launched at a time: The number of satellites girding the globe will rise at a single stroke from 14 to 18.
Meanwhile, the European Union is set to declare Galileo operational for initial services at the end of this year, bringing the system to the point where it can finally start serving users.
Paul Verhoef, director of the Galileo Programme and Navigation-related Activities, European Space Agency.
When Galileo Meets Ariane
November’s launch has been years in the making, employing a specially customized variant of Europe’s heavy-lift workhorse rocket called the Ariane 5 ES (Evolution Storable) Galileo. It has more powerful lower stages and a reignitable upper stage, first used in 2008 to supply the low-Earth orbiting International Space Station.
This new launcher design, adapted beginning in 2012 for Galileo, will carry a lower mass payload — four fully-fuelled 738-kg Galileo satellites plus their supporting dispenser — but must haul it to the much higher altitude of medium-Earth orbit, 23,522 km.
This precisely targeted orbit actually lies 300 km above the Galileo constellation’s final working altitude, leaving Ariane’s upper stage in a stable graveyard orbit, while the quartet of satellites maneuver themselves down to their final height.
Satellites. The satellites continue unchanged from those preceding them: Galileo full operational-capability (FOC) satellites with platforms from OHB in Germany and navigation payloads from Surrey Satellite Technology Ltd in the UK.
All 14 FOC satellites follow the first four in-orbit validation (IOV) satellites launched in 2011 and 2012; these four validated overall Galileo system design with the first wholly European navigation fix in March 2013.
Carrier. The four-satellite dispenser, the interface between the satellites and its launcher, is a wholly new design by Airbus Defence and Space. Its first role is to hold the satellites safely in position during their orbital flight and then to gently release them in separate directions. Its structure has been specially tuned to prevent harmful oscillations being triggered by the vibration and noise of launch. Its design was validated using complex finite-element modeling software, followed by practical testing of the dispenser together with dummy satellites.
Launcher. Ariane’s interstage Vehicle Equipment Bay, hosting the rocket’s avionic brain, underwent a redesign to reduce mass. Engineers also had to take into account this Ariane ES version’s flight time, much longer than any of its predecessors, more than four hours in all.
This involved a reworking of the launcher’s electronics and thermal subsystems, to ensure it maintains an optimal operational environment throughout a ballistic coast phase of more than three hours, between two firings of its EPS storable propellant upper stage. Two further Ariane 5 SE Galileo flights are planned to follow, one each for the remaining orbital planes.
Members of the joint Galileo Launch and Early Operations Phase (LEOP) team at work in CNES Toulouse. A joint team from ESA and France’s CNES space agency oversee Galileo LEOPs – the initial switching on and checking and configuration of satellite systems. LEOP is run from either ESOC or CNES Toulouse, on an alternating basis. (Photo: ESA)
Ground Control. This launch will mark the first time that ESA carries out launch and early operations (LEOP) for four satellites simultaneously. Usually, simply shepherding a spacecraft through the first critical days in orbit is a demanding enough task. A combined team from ESA and France’s CNES space agency based in Toulouse will make contact, establish control, and then see the four satellites through their initial critical activities. Within the combined team, each position is paired with a counterpart from the other agency to provide three mixed shifts around the clock for these first crucial days. This same team has conducted all Galileo early operations to date alternately from Toulouse or ESA’s ESOC control center in Germany.
The work starts with an initial check of on-board health and attitude, progressing to ensure each satellite’s pair of 1 x 5-meter solar wings are deployed and tracking the Sun, and then to point their antennas back towards Earth. Next comes a series of thruster firings to set the satellites onto a drift course into their final orbit, at which point they can be handed over to the Galileo Control Centre in Oberpfaffenhofen, Germany, for routine operations, and to ESA’s Redu Centre in Belgium to commence a few months of detailed payload testing.
Galileo at Your Service
Around the same time as this key launch, GSAT-210 and GSAT-211, the two previous satellites launched in May of this year, will have completed their in-orbit testing, allowing them to be formally certified as operational members of the constellation. The four new satellites should follow them into operational status by mid-2017. However, the Galileo system will reach initial operational status without these latest six satellites. The European Commission on behalf of the European Union expects to declare the system operational and ready to offer initial services before the end of this year.
This will mark a major milestone in the programme, awaited by many citizens in Europe and around the globe. Everyone with a Galileo-enabled receiver will be able to benefit from improved positioning, supplementing the already operational GPS constellation. ESA and the European GNSS Agency (GSA) have been working with European manufacturers of mass-market satnav chips and receivers to ensure that their products are Galileo-ready, offering detailed laboratory testing to close the loop between Galileo and industry.
Transition. In parallel to the declaration of initial services, there will also be an institutional change, as the GSA takes up its role overseeing the exploitation of Galileo. At the start of 2017, the formal handover of Galileo infrastructure will be initiated, targeted to conclude by the middle of the year. This mission includes not only the Galileo satellites in space but also the far-flung ground stations located on every continent, essential to the continued high-performance operations of the Galileo system. It also includes the two European Galileo control centers, with the signals overseen from Fucino in Italy and the platforms monitored from Oberpfaffenhofen, plus the communication infrastructure connecting them all together.
In the history of ESA, a research and development agency, this kind of handover to an operational body is not unprecedented; the agency handed Europe’s Meteosat weather satellites over to the newly created Eumetsat organisation, and pioneering telecommunication satellites came under the control of Eutelsat and Inmarsat. However, the Galileo ground segment will hold a special place in ESA history as one of the most complicated developments it has ever undertaken, serving to maintain the signals from the satellites to a nanosecond-scale of performance.
ESA will maintain its role of system design authority and system procurement agent, continuing to support system exploitation as it prepares for the follow-on Galileo Second Generation (G2G) design, supported through the EU’s Horizon 2020 programme. For example, the current contract of Galileo’s ground support operator will end next year, so ESA is supporting the GSA in initiating the contractual process to select a replacement operator. This contract covers all the interaction between the ground segment elements which are vital to the system as a whole. Maintaining continuity of service with transition to the new operator will certainly present a big challenge to the entire team, but one we are confident of meeting.
Upgrade. In parallel, 2017 will see the upgrade of various elements of the Galileo Ground Segment to reinforce its robustness, including updated releases to the Galileo Control Segment overseeing the satellites and the Galileo Mission Segment, overseeing the navigation signals. A new release of elements of the Galileo Security Facility, for security monitoring of the system, as well as the secure Public Regulated Service, will be deployed at the two Galileo Security Monitoring Centres.
The Galileo Ground Segment will gain a sixth tracking telemetry and control facility, for monitoring the satellite platforms in Papeete, Tahiti, and additional processing chains for increased redundancy will be deployed across the Uplink Stations in Kourou, Reunion and Noumea used to update the navigation message information. Similar redundant chains will be finalized for all 15 current Galileo Sensor Stations, which perform continuous collection of Galileo signals to identify the tiniest clock error or satellite drift.
New Satellites. The production of the satellites themselves continues to maintain a steady rhythm, with a production line stretching from suppliers across Europe to OHB and SSTL and then to ESA’s ESTEC Test Centre in the Netherlands for acceptance testing, based on a wide range of simulated space tests. The acceptance of the next satellites to launch is scheduled for this year’s end. Along with the two more Ariane 5 launches to come — one in the second half of 2017 and another in 2018 — the current plan is to commission further launch services as well as additional satellites in order to have Galileo fully operational by 2020. For these launches, Galileo may be the first customer of the new Ariane-6 launch vehicle.
EGNOS. Along with the progress of Galileo, contracts are planned to cater for the further development of the ESA-designed European Geostationary Navigation Overlay Service, Europe’s first navigation system. EGNOS was certified for safety-of-life aviation use in 2011, and is managed by the European Commission through a contract with operator the European Satellite Services Provider, based in France. ESA will support the technical evolution of EGNOS version 3, intended as multi-constellation in nature, again through the Horizon 2020 framework.
Finally, ESA is also addressing the challenges of satellite navigation beyond Galileo through the creation of the Navigation Innovation and Support Programme (NAVISP), which will be proposed to Europe’s space ministers for approval in December. Applying ESA’s expertise from Galileo and EGNOS, the optional NAVISP will undertake research work in support of ESA Member States’ national objectives and industrial competitiveness in the upstream and downstream navigation sector, including the fusion of satellite navigation with various disruptive technologies and complementary positioning techniques.
The multi-agency team behind the ESA-designed EGNOS augmentation system — making it possible for European aircraft to safely rely on satnav signals — has received a prestigious award from France’s national aerospace academy.
As our region’s own satellite-based augmentation system (SBAS), the European Geostationary Navigation Overlay Service (EGNOS) improves the precision of GPS signals over most European territory, while also providing continuous and reliable updates on their integrity.
Didier Flament, heading ESA’s EGNOS and SBAS Division, joined Mariluz de Mateo of Spain’s ENAIRE air traffic management agency, working on Europe’s Single European Sky Traffic Management Research (SESAR), and Jean-Marc Pieplu, overseeing EGNOS exploitation at the European Global Navigation Satellite System Agency (GSA) in receiving Vermeil Medals from France’s Académie de l’Air et de l’Espace in Toulouse.
The medals were awarded to the trio during the annual Séance Solennelle de l’AAE on Nov. 25.
EGNOS team: (from left) Jean-Marc Pieplu, overseeing EGNOS at the GSA; Mariluz de Mateo of Spain’s ENAIRE air traffic management agency, working on SESAR; and Didier Flament, heading ESA’s EGNOS and SBAS Division.
“This award recognizes the success of the EGNOS programme,” comments Didier. “It has been a long-term effort, which began with a first demonstration step called European Complement to GPS, studied and implemented by CNES, French Civil Aviation and the ONERA national aerospace research centre between 1987 and 1995.
“This was then followed by the European ESA ARTES-9 programme, started 20 years ago this year. So beyond the three nominees, the award goes to the various teams from ESA, CNES, civil aviation agencies and industry which have contributed to its success.“
While Galileo is on the verge of entering initial operational service, EGNOS has already been operational for many years: it began open service in 2009, and became available for ‘safety-of-life’ use including aviation in March 2011.
A network of 40 ground monitoring stations performs an independent measurement of GPS signals, so that corrections can be calculated and then passed to users immediately via a trio of geostationary satellites. A several-fold increase in precision is therefore delivered.
The result is that the EGNOS-augmented signals are guaranteed to meet the extremely high performance standards set out by the International Civil Aviation Organisation standard (ICAO SARPS), as all other similar regional SBAS systems.
Compliance to these standards is also ensuring full interoperability of these systems and seamless transition from one region to another for the end user – the pilot of an equipped aircraft.
The signals from space can therefore be relied on routinely for the safety-critical task of vertically guiding aircraft during landing approaches.
Today, more than 170 European airports in 19 countries use EGNOS, projected to increase to 346 in 25 states by 2020, according to Eurocontrol.
Following its initial design and development by ESA, ownership of the EGNOS system was passed to the European Commission in March 2009, and is currently operated on behalf of the EC’s GSA by an operator based in France, the European Satellite Services Provider.
ESA retains a role in procuring EGNOS’s future evolution, in particular the second generation of EGNOS aiming at augmenting all new modernized GPS signals and Galileo signals. ESA’s role includes liaising with other regional SBAS system providers to agree on common next-generational working standards through the international Interoperability Working Group, including making use of Galileo and additional satnav signals.
The most recent meeting of this working group was hosted by the Agency for Aerial Navigation Safety in Africa and Madagascar Nov. 29–30 in Dakar, Senegal.
