GPS World

Tag: open service

  • Directions 2020: Galileo Moves Ahead

    Directions 2020: Galileo Moves Ahead

    By Javier Benedicto
    Head, Galileo Programme department,
    European Space Agency

    Javier Benedicto, left, accept the Satellites Leadership Award on behalf of Giuliano Gatti of the European Space Agency, from Phil Froom of Rockwell Collins. (Photo: Melanie Beus)
    Javier Benedicto, left, accept the 2018 GPS World Satellites Leadership Award on behalf of Giuliano Gatti of the European Space Agency, from Phil Froom of Rockwell Collins. (Photo: Melanie Beus)

    Since the Galileo initial services declaration in December 2016, the Galileo Program has been providing global PNT and search-and-rescue services for users worldwide. The European GNSS Agency (GSA) just issued its GNSS 2019 Market Report in October, providing a complete overview of the current status and trends of the GNSS worldwide market with focus on European GNSS (Galileo and EGNOS) applications and services.

    In parallel with service provision, the Galileo Program is undertaking extensive infrastructure development and deployment activities to reach Full Operational Capability (FOC), incorporating new service capabilities, but above all aiming at increasing the robustness and resilience of the system infrastructure, operations and service provision.

    Galileo’s signal-in-space quality has steadily improved over the past few years, reaching in 2019 a best signal-in-space error (SISE) of about 0.25 meters (95%, global average; Figure 1). This has been achieved through a combination of several factors, including the increased number of operational satellites, enhanced versions of the Ground Mission Segment, and higher uplink rate of the navigation message (lower age of data). This performance is well within Galileo’s initial service accuracy commitments, as defined in the public Open Service – Service Definition Document (OS SDD).

    Figure 1. Long-term historical SISE plot over a 30-day sliding window, constellation averaged. (Image: ESA)
    Figure 1. Long-term historical SISE plot over a 30-day sliding window, constellation averaged. (Image: ESA)

    Figures 2 and 3 (see page 40) show Galileo’s timing performance as broadcast UTC offset and GGTO accuracy. The evaluation was performed with calibrated GPS/Galileo timing receivers operated in UTC(k) laboratory (PTB, INRIM). Again, the initial timing service commitments have been fully met.

    Figure 2. Galileo Broadcast UTC offset accuracy performance. (Image: ESA)
    Figure 2. Galileo Broadcast UTC offset accuracy performance. (Image: ESA)
    Figure 3. Galileo GGTO offset accuracy performance. (Image: ESA)
    Figure 3. Galileo GGTO offset accuracy performance. (Image: ESA)

    Probably the most significant discriminator of Galileo compared to other GNSS is its capability to broadcast multi-frequency (E1, E6, E5) signal components on all operational satellites. The position performance of a dual-frequency user receiver on-ground is shown in Figure 4. This measurement from June 2019 demonstrates a Galileo position accuracy well below 2 m (95%).

    Figure 4. Galileo position accuracy performance, dual-frequency, June 2019. (Image: ESA)
    Figure 4. Galileo position accuracy performance, dual-frequency, June 2019. (Image: ESA)

    With the aim of further improving the Open Service (OS) performance, three newly introduced I/NAV message improvements on Galileo E1-B are under implementation, namely FEC2 Reed-Solomon Clock and Ephemeris (CED), Reduced CED, and Secondary Synchronization Pattern (SSP). Galileo Open Service (OS) users will benefit from improved robustness in terms of navigation data retrieval in challenging environments, in addition to facilitating a reduced time to first fix. Those I/NAV improvements on Galileo E1-B are backwards compatible with previously released OS SIS ICDs.

    In addition, Galileo infrastructure is currently being upgraded to provide means for OS authentication. The protocol proposed uses the E1B External Data Broadcast Service (EDBS) to provide authentication data to the user. The OS Navigation Message Authentication (NMA) is based on an adaptation of the Timed Efficient Stream Loss-tolerant Authentication (TESLA) protocol.

    Beyond the OS, the Galileo system has been designed to allow for the dissemination of value-added data, such as high accuracy and authentication, in the E6B signal component. The component has been designed to broadcast the Galileo High Accuracy Service based on the provision of accurate satellite data (clocks, orbits and biases) and atmospheric data (mainly ionospheric corrections) to enable multi-frequency multi-constellation PPP with correction data transmitted through an open format in the Galileo E6B signal.

    The introduction in early 2020 of the automatic acknowledgment of the SAR/Galileo Return Link Message (RLM) as part of the Cospas-Sarsat system will enable space assets to be used for search and rescue — persons in distress will get swift acknowledgement that their alert has been detected and located. The Return Link is the means to interact with a SAR beacon, improving the effectiveness of SAR operations. Extensive testing has demonstrated that the median latency for the reception of a return link message on the ground is 14.2 seconds, while 99% of messages are received within 57 seconds, after the request for the RLM transmission is delivered to Galileo (from Cospas-Sarsat to the RLSP). At the same time, the measured rate of reception was 100%, considering line-of-sight availability, thanks to the very robust Galileo navigation data link. This performance has been demonstrated to be uniform across the globe, as shown in Figure 5.

    Figure 5. Beacon activation map and RLM delivery latency through the Galileo system. (Image: ESA)
    Figure 5. Beacon activation map and RLM delivery latency through the Galileo system. (Image: ESA)

    Following the re-profiling of the Galileo Safety-of-Life (SoL) service, Galileo is meant to be exploited through dual-frequency multi-constellation (DFMC) SBAS and will support the provision of integrity through the concept of Horizontal Advanced Receiver Autonomous Integrity Monitoring (H-ARAIM). To allow the exploitation of Galileo for these SoL applications, a thorough analysis of the actual signal-in-space (SiS) performance and of potential feared events critical for SoL users is key. In this context, the Galileo Integrity Failure Mode and Effect Analysis (IFMEA) process is implemented through measurements and review of the system design, including feared-events characterization.

    Ground Segment Brings Robustness

    Galileo telemetry and telecommand ground station. (Photo: ESA)
    Galileo telemetry and telecommand ground station. (Photo: ESA)

    Galileo’s Ground Segment is being upgraded to fully redundant control centers. These include processing and storage, monitoring and control facilities, and security monitoring centers. A worldwide network of Galileo Sensor Stations (GSS) allows monitoring and measuring of satellite signals; uplink stations allow dissemination of the navigation message to users through Galileo satellites; and telemetry, tracking and control (TTC) stations allow monitoring and control of the satellites.

    Ground segment upgrades under production by Thales Alenia Space France (in charge of the ground mission segment and security monitoring) and GMV Spain (in charge of the ground control segment) are addressing increased service robustness, through the introduction of a more flexible infrastructure with a significant technology refresh, improved security, service continuity, enhanced service performances, and enhanced operability features.

    One important objective of the ongoing upgrades is to implement a modern infrastructure, based on leading virtualization technologies. This modernized infrastructure will make it possible to easily accommodate hardware and software changes without requiring significant redesign or requalification, and will minimize the impact to Galileo service operations — under responsibility of Spaceopal GmbH — during future deployment activities.

    Batch 3, Ariane 6 Under Production

    Ariane 6 on the launchpad. (Artist's concept: ESA)
    Ariane 6 on the launchpad. (Artist’s concept: ESA)

    The production of Batch 3 of 12 additional Galileo FOC satellites is proceeding, aiming at readiness for launch by the end of 2020 onward. The satellite design includes a selected number of improvements compared to the 22 FOC satellites launched previously and built by the same satellite manufacturer OHB Systems.

    The different stages of assembly, integration and initial test phase in the OHB production plant in Bremen have already started, before shipment to ESA-ESTEC in the Netherlands for the environmental test campaign consisting of thermal vacuum, mechanical tests, interface verification with the launcher and system end-to-end performance tests with the elements of the Galileo ground segment.

    Following the phasing out of the Ariane 5 SE launcher, the third batch of Galileo satellites will be progressively launched with the new Ariane 62 launcher vehicle, the two solid-booster variant of Ariane 6 now in the final stages of development.

    Evolution to Meet User Needs

    The Galileo Second Generation roadmap has achieved maturity in 2019 and is now entering the preliminary design and implementation phase. Based on the EU’s H2020 Galileo Second Generation activities managed by ESA, and the GSA prospective market analysis, the European Commission, in close consultation with EU member states, has agreed on an ambitious set of long-term PNT goals for the future European GNSS infrastructures.

    Technology pre-developments, critical engineering activities and synergic design activities between space and ground infrastructure are being conducted. This will translate into the progressive deployment of a complete set of space/ground infrastructure that is tailored to satisfy the diversified user needs in four main dimensions:

    • Satellite and ground segment infrastructure with capabilities that can dynamically adapt to current and future user needs. Key drivers are flexibility and robustness, ensuring fast time to market to meet user needs.
    • Full synergy between GNSS and SBAS systems infrastructure, to complement and enhance the service portfolio. This will allow segmentation and complementarity of safety-critical services and extension to all new PNT services available today, including high-accuracy positioning integrity.
    • Enhanced integration with terrestrial systems — 5G/6G, signals of opportunity (SOOP), terrestrial beacon systems (TBS). ESA and GSA have been actively leading the 5G positioning standardization worldwide in collaboration with public and private institutions inside 3GPP and will soon move toward the start of standardization of 6G terrestrial positioning and GNSS interconnection technologies.
    • Full complementarity with external sensors (such as INS, barometer and lidar) and application environments (low-power devices and internet of things) so that the Galileo Second Generation Infrastructure enhances and complements the capabilities provided by these external means.

    A key pillar for this long-term strategy is the Galileo transition satellites. The competitive procurement procedure for the first batch of transition satellites is coming in 2020. The flexibility and robustness of these satellites will allow the European PNT infrastructure to satisfy all the different user needs in the next decade. This procurement — together with others at system, ground segment and technology level — will enable the start of the in-orbit validation of second-generation capabilities from 2025 onward.

    Additional ground and test infrastructure are in early engineering analysis, design and technology development, in order to proceed with additional procurements for experimental and operational usage, starting early in the 2020s.

  • Galileo constellation grows by 4 satellites

    Galileo constellation grows by 4 satellites

    Galileo satellites GSAT0215, GSAT0216, GSAT0217 and GSAT0218, launched in December 2017, were commissioned for operational use as of Oct. 12, with all signals usable: Open Service, Public Regulated Service and Search and Rescue Service.

    This increases the number of Galileo satellites that are available for service provision to 18. Initial operational capability for the constellation was declared on December 15 2016.

    The additions to the GNSS almanac include the following:

    GSAT0215:  space vehicle E21 aka Nicole, occupying slot A03 if the constellation, with its payload running on a phased hydrogen maser (PHM) clock.

    GSAT0216: E25, Zofia, slot A07, PHM clock.

    GSAT02017: E27, Alexandre, slot A04, PHM clock.

    GSAT0218: E31, Irina, slot A01, PHM clock

    Each satellite weighs 715 kilo;  measures 2.7 x 1.2 x 1.1 meters with a deployed solar array span of 14.67 meters; has onboard power of 1,900 W; and broadcasts navigation signals in 3 bands: E5, E6 and E1. Design life of the new satellites is more than 12 years.

    Satellites GSAT-219 (Tara), GSAT-220 (Samuel), GSAT-221 (Anna) and GSAT-222 (Ellen) were launched on July 25 and are currently listed as under commissioning.

    Galileo status information

    Updated information on the status of the Galileo constellation can be found in the Constellation Status section of the European GNSS Service Centre’s (GSC’s) website.

    Delivery person uses Galileo on a mobile device to deliver a package. (Photo: GSA)
    Delivery person uses Galileo on a mobile device to deliver a package. (Photo: GSA)

    According the the European GNSS Agency (GSA), more than 100 million devices are using Galileo today.

    For more information on user technology, see GSA’s 2nd User Technology Report and a commentary, “Farewell to the Golden Age of GPS.”

    To keep track of Galileo-enabled devices serving a variety of needs as they become available, visit usegalileo.eu.

    The Galileo Initial Services allow the use of Galileo Open Service (OS), which enables a free of charge, global ranging, positioning and timing service for the OS users.

    Galileo is interoperable with the GNSS constellations (GPS, GLONASS, Beidou). By offering dual frequencies as standard, Galileo is set to deliver real-time positioning accuracy down to the meter range.

    For questions about Galileo, contact the GSC Helpdesk.

    Four Galileo satellites were added to constellation in October 2018. (Image: GSA)
    Four Galileo satellites were added to constellation in October 2018. (Image: GSA)
  • Galileo provides healthy signals 97.33 percent of the time

    Galileo provides healthy signals 97.33 percent of the time

    Europe’s Galileo satellite navigation system has undergone its first performance report since it started work at the end of last year, and it passed with flying colors, said the European Space Agency.

    The European GNSS Agency, GSA, through its GNSS Service Centre, has published the first of its regular quarterly performance reports on Galileo. This European GNSS (Galileo) Initial Services Open Service report, now available online, covers the first three months of 2017 and documents the good performance of Galileo Initial Services to date.

    The report shows the 11 satellites then operating in the Galileo constellation were able to provide healthy signals 97.33 percent of the time on a per satellite basis, with a ranging accuracy better than 1.07 m and disseminating global UTC time within its signal to within 30 billionths of a second on a 95 percentile monthly basis.

    “Galileo Initial Services were declared by the European Commission on 15 December 2016,” said Joerg Hahn of ESA’s Galileo System Office.

    “It was thanks to the tremendous effort of ESA’s Galileo team working closely together with colleagues from the commission and GSA that this milestone could be achieved: the key pillars for reaching are the currently deployed Galileo satellites in combination with the global Galileo ground segment infrastructure, defined and implemented by the ESA team with their respective industry partners.”

    The Initial Service performance levels achieved by the system are monitored using two complementary monitoring platforms: the Time and Geodetic Validation Facility, an independent precision time-measuring system accurate to a billionth of a second — using an ensemble of atomic clocks located at ESA’s ESTEC technical centre in Noordwijk, the Netherlands — and the Galileo System Evaluation Equipment, GALSEE, based in Rome.

    The steadily declining Signal in Space Ranging Error (SISE) of the Galileo constellation from 2014 to the present.

    In the future, the independent monitoring of the services will be carried out by GSA’s Galileo Reference Centre, currently taking shape beside ESTEC in Noordwijk. The results for the first quarter of 2017 show the measured performances are generally far better than the minimum performance levels identified in the Service Definition Documents.

    “Looking back over the ranging accuracy of the Galileo constellation from the time of the very first positioning fix in 2014 to the present, the overall performance trend for the Open Service is very positive,” Joerg said.

    “It has reached values of less than 1 m in recent months, being already competitive with other satellite navigation systems.

    “The high-quality ranging service enables user level positioning with a typical accuracy of around 3 m on the ground and 5 m in altitude during periods when four satellites are visible. With the limited infrastructure so far deployed, current horizontal position fixes can be achieved during more than 80 percent of the time with accuracies better than 10 meters.

    “This user level performance is expected to improve with the launch of more satellites making the provided Galileo services more accurate, more available and more robust for end users.”

  • First Galileo open service performance report published

    Click for PDF.

    The European GNSS Agency (GSA) has published its first Galileo Open Service quarterly performance report.

    The report, which covers the first three months of 2017, is available online in the GSC Electronic Library, or directly here.

    Following the Declaration of Initial Services in December 2016, the GSA will publish a new Galileo Initial Services Open Service report after each quarter. The quarterly reports aim to provide the public with the latest information on the Galileo Open Service’s performance.

    The document reports on such parameters as:

    • Galileo Initial Open Service ranging performance
    • Galileo Coordinated Universal Time (UTC) dissemination and Galileo to GPS time offset (GGTO) determination performance
    • Galileo positioning performance
    • Timely publication of Notice Advisory to Galileo Users

    Each of these parameters is examined with respect to their minimum performance levels (MPLs), as declared in the European GNSS (Galileo) Open Service Definition Document (OS-SDD).

    Highlights from Q1 2017

    In the first quarterly reporting period after the Declaration of Galileo Initial Services, the measured Galileo Initial Open Service performance figures generally exceeded the MPL targets specified in the OS-SDD by significant margins.

    Some highlights from the report:

    • Availability of the Galileo ranging service at the worst user location, with monthly values of 100 percent, is significantly above expectations, where the MPL is 87 percent.
    • The signal in space ranging accuracy shows a 95th percentile monthly accuracy better than 1.07 [m] for individual space vehicles.
    • Availability of the Galileo UTC time determination service was achieved, with a monthly value of 100 percent, compared to the [OS-SDD] MPL target of 87 percent.
    • Availability of GGTO determination (not declared as a service in this phase) was 100 percent in January and March. February showed a slightly lower figure of 96.44 percent, although still well above the [OS-SDD] MPL target of 80 percent.
    • Excellent values were achieved for UTC time dissemination service accuracy. The measured Galileo Initial Open Service performance figures generally exceeded the MPL targets specified in the OS-SDD by significant margins.

    For up-to-date information, check the European GNSS Service Centre (GSC) website. For all support related to Galileo, contact the Galileo Help Desk. The Help Desk allows close interaction with users, both to support the exploitation of Galileo services and to collect relevant information on signal performance as observed by the users themselves.

  • Rockwell Collins and QinetiQ join on next-generation GNSS receivers

    Rockwell Collins and QinetiQ have signed a global alliance agreement to collaborate on the development of next-generation, multi-constellation open-service and secure GNSS receivers.

    The effort will support the mission needs of military, government and critical national infrastructure.

    The family of receivers being developed will provide military, government and professional users the flexibility of selecting relevant GNSS capability to meet operational, geographical or budgetary needs and provide GNSS accuracy and timing.

    This will improve safety, increase mission effectiveness and reduce operational costs for ground troops, vehicles and high-dynamics GNSS-guided weapons, Rockwell Collins said.

    Rockwell Collins is major contractor for secure military GPS receivers and QinetiQ is an expert in the field of open-service solutions with access to critical satellite navigation system technologies that enable the development of multi-constellation solutions.

    “This alliance agreement with QinetiQ is a great opportunity to bring together our strengths,” said Colin Mahoney, senior vice president of international and service solutions for Rockwell Collins. “Working together, our customers will experience unprecedented levels of availability, accuracy and assurance of positioning, navigation and timing for conducting their missions.”

    “As we move into the era of multi-constellation satellite receivers, this market-leading agreement and the investments of both companies sends a clear message to our customers and shareholders that QinetiQ and Rockwell Collins are taking every step necessary to stay at the forefront of GNSS technical development and product delivery,” said Steve Wadey, CEO of QinetiQ. “The development will be centered in Europe, led from the U.K., supporting the global market.”