GPS World

Tag: Directions 2022

  • Directions 2022: GPS positioned for the future

    Directions 2022: GPS positioned for the future

    By Michael J. Dunn, Space Systems Command, Capability Area Integrator for Positioning, Navigation and Timing

    The Global Positioning System is the premier positioning, navigation and timing (PNT) source for more than six billion users worldwide. It is vital to the function of all 16 of the United States’ essential critical infrastructure components. Life as we know it relies on the essential services that GPS provides.

    The United States Space Force (USSF) is committed to maintaining a healthy GPS constellation that continues to deliver the “gold standard” of PNT availability and reliability throughout the world. Continuous improvements in equipment and performance have been a hallmark of the enterprise since its inception. 2021 was no exception, with a continued record-setting delivery of new capabilities.

    Space Systems Command (SSC) at Los Angeles Air Force Base in El Segundo, California, is laser-focused on delivering the most important modernization in GPS history. The government and industry team are committed to bringing major upgrades to the space, control and user-equipment segments. It is an exhilarating time for the GPS enterprise. The specific updates within each segment cement the continued evolution in GPS and the USSF commitment to delivering advanced capabilities to the nation and the world.

    Space Segment

    Currently, 37 GPS satellites are on orbit, with 29 satellites set healthy. The baseline constellation requirement is 24 satellites. The system continues to perform in stellar fashion, providing an average 48-centimeter position accuracy throughout 2021.

    Orbital systems modernization is focused on the GPS III satellite fleet, and the program continues to deliver peerless capabilities. GPS III space vehicles (SV) 1–4 were all operationally accepted in 2020. In 2021, the most notable event was the launch of GPS III SV05 in June. The satellite successfully achieved operational acceptance and mission-capable status for USSF in just under two weeks: a new record. SVs 6–8 are available for launch and are awaiting their launch windows. SV09 system-level testing is in progress. SV10 component deliveries continue. GPS III provides up to eight times better anti-jam and a new L1C signal to improve user connectivity.

    For the GPS IIIF program, the long-range picture remains bright as the contract for GPS IIIF SVs 15–17 was awarded in October 2021. The delivery of the first GPS IIIF is expected early in 2026. GPS IIIF will build upon the tremendous increase in capability provided by GPS III with the addition of a search-and-rescue payload, a laser retroreflector array for precise ranging, a fully digital navigation payload, and a Regional Military Protect capability that will provide 60 times greater anti-jam for operations in electromagnetically hostile environments.

    GPS III space vehicle 05 (GPS III-SV05) launched in June 2021 from Cape Canaveral Space Force Base, Florida, aboard a SpaceX Falcon 9 launch vehicle. (Photo: SpaceX)
    GPS III space vehicle 05 (GPS III-SV05) launched in June 2021 from Cape Canaveral Space Force Base, Florida, aboard a SpaceX Falcon 9 launch vehicle. (Photo: SpaceX)

    Control Segment

    The next-generation Operational Control System (OCX) continues to execute within its program baseline. OCX will provide enhanced command and control capabilities, modernized architecture, robust information assurance and cyber security.

    OCX’s incremental development approach began with OCX Block 0, which is the launch and checkout system (LCS) for GPS III. The LCS successfully supported the launch and checkout of GPS III SV 01–05. OCX Blocks 1 and 2 will control all legacy GPS III satellites and both legacy and modernized signals.

    Despite barriers presented by the global COVID-19 pandemic, all 17 global OCX monitoring station installations were completed in July 2021. Most of the remaining equipment was fielded throughout December 2021. System integration and verification continues with transition to operations scheduled for early 2023.

    The Next Generation OCX 3F contract was awarded in April 2021. The program will modify OCX to launch and control GPS IIIF satellites with enhanced capabilities. Acquisition Milestone B is expected in 2022, and operational acceptance is planned for 2027.

    MGUE: The future warfighter’s battlespace edge. (Image: Space Systems Command Production Corps)
    MGUE: The future warfighter’s battlespace edge. (Image: Space Systems Command Production Corps)

    User Equipment Segment

    Millions of GPS receivers are fielded, but very few of them can use the military code (M-code) signal that is being broadcast by 24 GPS SVs. To keep our competitive advantage against the adversary, the GPS enterprise is focused on developing modernized GPS user equipment (MGUE) that takes advantage of these signals. The MGUE program is a joint service program developing modernized, M-code-capable military GPS receivers. The program is broken into two increments (Inc 1 and Inc 2). Both are designed to deliver secure PNT performance, allow navigation warfare operations, enhance anti-jam, anti-spoof and anti-tamper, and enable Blue Force Electronic Attack.

    MGUE Inc 1 achieved a major milestone in September 2021 with successful testing on the Marine Corps Joint Light Tactical Vehicle (JLTV). The event took place in an electromagnetically degraded GPS environment at White Sands Missile Range, New Mexico. The JLTV is a pathfinder lead platform for the MGUE program. Lead platforms for the other services, the Army Stryker combat vehicle, Air Force B-2 bomber, and Navy Arleigh-Burke Class Guided Missile Destroyer, will commence integration testing in FY23 and FY24.

    MGUE Inc 2 development continues to make progress in maturing the next generation ASIC technology required for all weapon-system platforms to provide functionality and backward compatibility. It will deliver a miniature serial interface card in CY26 to support handheld and ground applications. Eventually, MGUE receiver cards will be loaded onto hundreds of Department of Defense (DOD) weapon systems.

    GPS III SV04 in Highbay (Photo: Lockheed Martin)
    GPS III SV04 in Highbay (Photo: Lockheed Martin)

    Partner Community

    The GPS enterprise is committed to cooperation on a global basis. It works closely with the DOD, the armed services, the U.S. Coast Guard, other federal agencies, the International Civil Aviation Organization and all the other global and regional navigation satellite systems toward the development of PNT in the global commons.

    A highlight of this cooperative work is GPS enterprise involvement in the National Executive Committee for Space-Based PNT (PNT EXCOM), which supports the interests of the various federal bodies, especially the Department of Transportation (DOT) and the Federal Aviation Administration (FAA). The PNT EXCOM is applying GPS technology to a broad variety of governmental activities, including the development of the Next Generation Air Transportation System and intelligent transportation systems.

    The GPS enterprise commitment to international partners is unwavering. Our support to the North Atlantic Treaty Organization (NATO) is ongoing with support to the Capability Panel 2 for Navigation working toward the integration of MGUE and compatibility arrangements with Europe’s Galileo system. A highlight this year was the first delivery of MGUE loan equipment to the United Kingdom, Canada, Germany, and the Republic of Korea. Germany is the first country to purchase MGUE equipment.

    Conclusion

    GPS is the foundation of global PNT and a cornerstone of modern life. Improvements to the enterprise are continual. As the nation moves into the complex and dynamic world of the coming decades, the dedicated military, civilian and industry professionals that provide this world-changing capability will continue their challenging and rewarding work. Semper Supra!

    The "encapsulation" of a GPS satellite. (Photo: U.S. Department of Defense)
    The “encapsulation” of a GPS satellite. (Photo: U.S. Department of Defense)
  • Directions 2022: Now 3 years old, QZSS hits its stride

    Directions 2022: Now 3 years old, QZSS hits its stride

    By Satoshi Kogure
    Director, National Space Policy Secretariat Cabinet Office, Japan/QZSS Strategy Office

    At 02:19:37 UTC on Oct. 26, 2021, a new satellite in the QZSS constellation — QZS-1R — was launched from the Tanegashima Space Center in Japan. It is the fifth satellite in the constellation and the replacement of the first satellite, launched in September 2010. 

    As of December 2021, initial on-orbit testing (IOT) and tuning of the precise orbit determination (POD) function in the ground control segment was ongoing. QZS-1R is the first QZSS satellite that will transmit the L1 C/B signal, splitting the power spectrum at the L1 center frequency by adopting BOC modulation on the existing C/A signal, to mitigate interference into the GPS L1 C/A signal. C/B signal transmission was verified during the IOT phase. QZS-1R will transmit the C/A signal continuously until QZS-5, 6 and 7 are launched and the noise floor increased. 

    The launch of QZS-1R was a milestone toward a sustainable national infrastructure for Japan. The Japanese government’s Cabinet Office (CAO) is trying to establish more secure positioning, navigation and timing (PNT) services by deploying seven satellites for the QZSS constellation. It will add three satellites to the current four around 2023. 

    This will give QZSS an independent PNT capability and enhance GNSS performance as well as robustness, and cover a broader area in the Asia Pacific region. CAO is still investigating the future of the QZSS constellation, including its final configuration and how to provide assured PNT services corresponding to future user requirements. However, it is thought that the full operational capability for Japan at minimum may be declared after the completion of the initial seven-satellite constellation. 

    Today, QZSS is providing ranging signals on L1C/A, L1C, L2C and L5 for all users able to acquire and track those signals. Those signals have the same RF properties and almost the same message format as the corresponding GPS signals — they are interoperable. 

    In addition, a unique characteristic of QZSS is that it transmits error correction messages available in Japan on separate channels — L1S, L1Sb and L6 — from those used to broadcast its ranging signals. Messaging functions are also provided through QZSS L1S and S-band two-way communication links on QZS-3 in support of disaster mitigation and relief operations in Japan. 

    CAO launched the QZSS operational services using a four-satellite constellation on Nov. 1, 2018. Its first three years of operation have provided much knowledge to improve their performance. The averaged signal-in-space user ranging error, a 95 percentile daily statistic, has been improved and achieved less than 1.0 meter, while the specification is 2.6 meters; the best daily value in the evaluation period (Aug. 31, 2020 to Sept. 1, 2021) was less than 0.5 meter for QZS-1, 2 and 3. 

    This remarkable improvement was shown on the Centimeter Level Augmentation Service (CLAS). According to the original design of CLAS, transmitted error corrections were for only 11 satellites in the GPS, QZSS and Galileo constellations. After two years of initial operation, we updated the ground control segment for CLAS to increase the number of augmented satellites from 11 to a maximum of 17. This increase in the number of satellites with error corrections leads to excellent improvement of CLAS performance in more challenging user environments such as urban and mountainous areas.  

    To improve the service performance further and measure new observables for satellite orbit clock estimation, inter-satellite ranging and two-way ranging functions between tracking station and satellite will be developed for QZS-5 to -7 and following satellites. The ground control segment will also be updated.

    Multi-GNSS ADvanced Orbit and Clock Augmentation (MADOCA) precise point positioning (PPP) will be implemented as a practical service no later than 2024. It is aiming to provide decimeter-level PPP service with broadcast of globally available satellite orbit and clock error corrections as well as code-phase and carrier-phase biases. 

    PPP has a well-known disadvantage: long convergence time. By using the marginal L6D channel on QZS-5 to -7, the ionospheric delay correction for wide area will be distributed. CAO will try to evaluate how such ionospheric correction could reduce the initial convergence time for the PPP calculation. In an experiment planned in collaboration with Asian Pacific countries, regional stations in the nationwide CORS network will be used for generating such corrections. 

    Early or Emergency Warning Service (EWS) is also expanding its service coverage into the region. The common EWS format is being jointly investigated by India, the European Union and Japan under the UN-ICG framework. The QZSS EWS for the Asia Pacific region through the L1S signal on QZS-1R, 2, 3 and 4 will be established after completion of a ground segment update around 2024. 

    Also see First Transmission of L1C/B by QZS-1R.

  • Directions 2022: Galileo FOC, G2 on the horizon

    Directions 2022: Galileo FOC, G2 on the horizon

    Galileo Second Generation Batch#1A satellites. (Image: ESA).
    Galileo Second Generation Batch#1A satellites. (Image: ESA).

    Successful European Cooperation

    Galileo is Europe’s civil global satellite navigation constellation and a major success, being the world’s most precise satnav system and offering meter-scale accuracy to more than two billion users around the globe.

    The signature of the Financial Framework Partnership Agreement (FFPA) on June 22, 2021, further strengthened effective cooperation between the European Commission (EC), the European Union Agency for the Space Program (EUSPA), and the European Space Agency (ESA) — key to successfully achieving a crucial EU Space Program component like Galileo in the current EU Multi Financial Framework (2021–2028).

    The EC is the program manager, with EUSPA acting as the exploitation manager and ESA as the system development prime.

    Stable Service Performance

    Galileo continues to deliver excellent service performance every month in a safe, secure and seamless manner. Delivery of Galileo services is managed by EUSPA, as the Galileo service provider, with industrial partner SpaceOpal, the Galileo service operator prime contractor. The performance of Galileo services is independently monitored by the Galileo Reference Center (GRC) and regularly published on the GNSS Service Center (GSC) web portal at www.gsc-europa.eu — both agencies were developed by GMV. The security of the Galileo System is monitored by the Galileo Security Monitoring Centers (GSMC), operated by EUSPA.

    With 22 satellites in service, the open service is already delivering more than 99% availability of PDOP <= 6 worldwide. This, together with the excellent ranging accuracy, suggests that most Galileo dual-frequency users are typically experiencing positioning accuracy in the order of only 2 to 3 meters.

    Timing users also continue to receive accurate (in the order of 5 ns) access to Galileo System Time, which they can trace to Universal Coordinated Time (UTC) through the corresponding offset parameters transmitted by the satellites.

    The SAR/Galileo service, contributing to COSPAS/SARSAT, continues to deliver both the Forward Link Service (FLS) and the Return Link Service (RLS) with more than 99% availability, allowing users in distress not only to issue an alert and be located within a few minutes, but also be notified that the alert was successfully processed and rescue is on the way. The SAR/Galileo control center is located in Toulouse (France) and operated by CNES under the authority of EUSPA. The excellent performance of the service has been demonstrated both through several rescue exercises and real-life emergencies.

    Galileo Launch 11

    Soyuz launcher VS-26 lifted off from French Guiana with the first pair of Galileo Batch 3 satellites on Dec. 5, 2021, at 01:19 CET. This marks the 11th Galileo launch of operational satellites in 10 years: a decade of hard work by Europe’s Galileo partners and European industry. With these satellites, the robustness of the constellation has increased, guaranteeing a higher level of service.

    Thanks to an upgrade of the Ground Control Segment, the Launch and Early Orbit Phase has been for the first time conducted directly from the Galileo Control Center, rather than requiring an external mission control site. This version of the ground segment increases overall reliability and cybersecurity and opens the way to significant expansion of the Galileo constellation, allowing command and control of up to 38 satellites. The development has been performed by an industrial consortium led by GMV, harnessing state-of-the-art technology using the latest solutions on the market.

    Galileo launch 11 from Europe’s spaceport in French Guyana. (Photo: ESA)
    Galileo launch 11 from Europe’s spaceport in French Guyana. (Photo: ESA)

    On Route to Full Operational Capability

    This year will pave the way toward Full Operational Capability of Galileo services.

    Industrial prime contractor OHB Systems has nearly completed production of the additional 10 recurrent satellites belonging to Galileo Batch 3. Six of them are undergoing final acceptance testing at the ESA satellite test center, and the other four are under integration at the satellite prime facilities.

    Preparation for Launch 12 has already started, with the satellites’ acceptance for a launch date planned in the first months of 2022, followed by Launch 13 in autumn. This is leading toward completion of the Galileo constellation, providing an increased availability of the Galileo signal in space for both GNSS and search-and-rescue users.

    From 2023 onward, the remaining Batch 3 satellites will be launched with the new Ariane 62 launch vehicle, a variant of Ariane 6 with two strap-on solid boosters. The launcher is undergoing the final stages of development, led by prime contractor ArianeGroup.

    The Galileo Ground Mission Segment will undergo a complete technological refresh, including hardware virtualization and porting of several million lines of code, performed by an industrial consortium led by Thales France. A series of improvements will be introduced to increase system resilience, including an extended mode of operation to improve service continuity and robustness.

    Cybersecurity monitoring of all the ground assets will be introduced as an overlay to the current ground infrastructure. The upgrade will undergo a rigorous level of qualification testing followed by worldwide deployment in a seamless way in both Galileo control centers, in both Galileo security monitoring centers, and at all remote locations without affecting continuity of service.

    The service facilities that contribute to the delivery of Galileo services (the European GNSS Service Center, the Galileo Reference Center, and the SAR data service providers) will also evolve to support not only the transition from Initial Services to Full Operational Capability, but also the early roll-out of service evolutions. In this regard, extensive work is ongoing to deliver an exciting set of improvements, some of which are already in development or testing, to reach the users in the year to come:

    • Improvements of the I/NAV signal to increase robustness and time-to-first-fix, while assuring full backward compatibility with legacy receivers.
    • OS Navigation Message Authentication (OS-NMA) to support applications that require trust in the authenticity of the data transmitted by the Galileo satellites (a public observation campaign was launched in November 2021 to engage stakeholders and collect their feedback before moving to the initial service provision).
    • An initial phase of the High Accuracy Service, delivering corrections in the Galileo E6 signal and over terrestrial network to allow users to perform precise point positioning over Europe; test signals were already transmitted with promising results.
    • A Search and Rescue Beacon Command Service complementing the SAR Return Link, providing improved capabilities to timely locate beacons under authorized emergency situations (such as the disappearance of Flight MH370 in the Indian Ocean in 2014).
    • A first implementation of an Emergency Warning Service over Europe, allowing the authorized national emergency-management authorities of the EU Member States to relay alert messages through Galileo signals, which can reach target areas even in case of disrupted terrestrial communications (such as due to floods or earthquakes).
    Galileo worldwide ground segment. (Credit: ESA)
    Galileo worldwide ground segment. (Credit: ESA)

    Second Generation in the Making

    The FFPA will bring Galileo to the next level with the development of the second generation, a further step forward with the use of many innovative technologies to guarantee the system’s unprecedented precision, robustness and flexibility.

    In parallel to the completion of the first generation of Galileo, Europe has conducted in recent years preparation activities for the Second Generation (G2). Elaborating on market, user and exploitation needs collected by EUSPA, ESA identified a number of system evolution scenarios, which were discussed among relevant EU stakeholders to select the second-generation mission and services baseline to build the system infrastructure.

    The evolution of Galileo capabilities will not only provide better services through advanced technical solutions identified by ESA, but will also ensure continuity of service and backward compatibility for
    first-generation legacy users.

    Two parallel contracts to develop and manufacture each of the six Galileo Second Generation Batch#1 satellites were kicked off in the first half of 2021 with Thales Alenia Space (Italy) and Airbus Defence & Space (Germany). The new G2 satellites will be constructed on a short time scale, with their first launch via Ariane-62 expected in less than four years, allowing them to commence operations in space as soon as possible. Both contracts have already undergone preliminary design reviews.

    Development of the G2 satellites is supported by the Galileo Payload Test Bed, which provides an early proof-of-concept of the advanced G2 payload architecture. These satellites will provide, among others, the following key innovations:

    • Reconfigurable fully digital navigation payload.
    • Point-to-point connection between satellites by Inter-Satellite-Link for command and control and ranging functionalities.
    • Electric propulsion for orbit-raising capabilities.
    • Advanced jamming and spoofing protection mechanisms to safeguard Galileo signals.

    System and Ground Segment definition studies, together with the associated technology pre-developments, have been performed, leading to the definition of the preliminary design and technical requirement baseline for the G2 system, a project involving most of Europe’s space industrial partners.

    The G2 In-Orbit Validation Ground Segment and System Test Bed have been defined and relevant procurement procedures are ongoing, with these objectives:

    • G2 Batch#1 satellites launch and early orbit phase, in-orbit testing and enhanced legacy services provision.
    • G2 new capabilities in-orbit validation, including prototyping and validation of all the novel technologies that can exploit the full capabilities of the G2 Batch#1 satellites.
    Galileo Second Generation Batch#1B satellites. (Image: ESA).
    Galileo Second Generation Batch#1B satellites. (Image: ESA).

    Definition activities for the G2 Initial Orbit Capability (IOC) are progressing well and are expected to converge in the first half of 2022, in order to establish the future roadmap for new G2 services provision in the years to come.

    2022 will be a key year for the evolution of Galileo Second Generation activities, through the consolidation of the first batch of G2 satellite design and development activities and the start of development of associated G2G IOV Ground Segment and System Test Beds.

    A bright future awaits Galileo, both through the completion of its Final Operational Capability and the start of evolution towards Galileo Second Generation.

    Guerric Pont is Galileo Exploitation Program manager for the European Union Agency for the Space Program (EUSPA).

    Marco Falcone is Galileo First Generation Project manager for the European Space Agency (ESA).

    Miguel Manteiga Bautista is Galileo Second Generation Project manager for the European Space Agency (ESA).

  • Directions 2022: A new epoch for GLONASS

    Directions 2022: A new epoch for GLONASS

    Figure 1. GLONASS high inclined space complex. (Image: Institute of Navigation Technology JSC)
    Figure 1. GLONASS high inclined space complex. (Image: Institute of Navigation Technology JSC)

    The digital transformation of the global economy requires precise time synchronization and valid object position information. Global navigation satellite systems (GNSS) are the most accurate tool for such tasks.

    This year will be 40th anniversary of the launch of the first GLONASS satellite, and we see that the quality of navigation services is driven by the characteristics of today’s satellite navigation signals.

    The first fourth-generation Glonass-K2 #13L satellite is scheduled for launch in 2022. It will broadcast a full ensemble of navigation signals — both Frequency Division Multiple Access (FDMA) signals in the L1 and L2 bands and Code Division Multiple Access (CDMA) signals in the L1, L2 and L3 bands. This long-awaited launch will cap a 10-year effort and begin to provide a new platform by broadcasting all the CDMA signals through a single antenna array on the satellite’s geometric axis.

    The FDMA antenna array is displaced by 0.9 m from this axis, but this arrangement is done on only two satellites. The next Glonass-K2 satellites, which will be launched beginning in 2024, will have a single antenna array for all navigation signals.

    The final second-generation Glonass-M satellite, scheduled to be placed in orbit next year, will provide services by open FDMA signals in the traditional bands at 1.6 GHz and 1.25 GHz. This satellite will be the seventh Glonass-M vehicle able to broadcast GLONASS L3 CDMA signals. There are only two Glonass-K satellites broadcasting this signal now, but more satellites with such a signal will be activated by the end of testing of the GLONASS modernized ground control facility.

    We expect the number of satellites able to provide this service to increase by two per year as we replace Glonass-M satellites with Glonass-K and Glonass-K2 satellites.

    As of this writing, 15 satellites (62% of the constellation) are working past their guaranteed life times, limiting our ability to increase the system’s accuracy. For the last decade, the signal-in-space range error (SISRE) was 1.4 m, despite the fact that newly launched satellites provide a SISRE of about 0.8 m.

    Glonass-K satellites will be launched to maintain the orbit constellation within the next three years, and the accuracy of their signals will be the same or even better. These satellites have a single antenna array for all three bands and could broadcast either FDMA or CDMA signals.

    In 2022, the constellation orbits will increase to six satellites in three planes, as we aim to increase the navigation service accuracy and availability (FIGURE 1). See TABLE 1 for satellite orbit parameters. This constellation will make it possible to increase navigation accuracy in the Eastern Hemisphere by about 25% through decreasing the value of the geometric factor.

    Table 1. Augmented orbit constellation parameters.
    Table 1. Augmented orbit constellation parameters.

    Additionally, this will greatly improve the availability of the GLONASS navigation service in difficult conditions, such as locations where current users can only receive navigation signals from satellites at least 25° above the horizon. New constellation satellites will be based on the Glonass-K platform, which has passed in-orbit qualification and proved it can provide SISRE at 0.3 m. The preliminary design proved that satellites on this platform could provide an in-orbit SISRE below 0.4 m with standard cesium on-board clocks. This signal-in-space accuracy level with valid ionospheric and tropospheric model data from the navigation signal will allow users to receive a position determination error below 2 m in the plane. Navigation services from these satellites will be provided by the CDMA signal in three frequency bands.

    The new satellite will weigh about 1,000 kg and be launched into orbit from both Russian spaceports (northern Plesetsk and eastern Vostochny) by the highly reliable Soyuz-2 rocket. The first launch is scheduled for 2026.

    One of GLONASS’ important tasks is to transmit the UTC (SU) national time scale to consumers. Over the past few years, significant results have been achieved in this area.

    • A complex of high-precision measuring instruments to compare the national coordinate timescale UTC (SU) with the GLONASS timescale was put into operation. These instruments include a transported quantum clock that provides timescale storage with an uncertainty of no more than 1 ns at an observation interval of one day, and with a transportation time of no more than 12 hours. It also provides duplex comparisons of timescales, comparing objects with the permissible uncertainty of ±1.5 ns.
    • Timescale storage complexes of secondary and working standards of time and frequency VET1-5 (Irkutsk), VET 1–19 (Novosibirsk), VET 1–7 (Khabarovsk) and RET1-1 (Petropavlovsk-Kamchatsky) were modernized and put into operation, providing an overall uncertainty of 3 · 10-15 and with a maximum permissible shift of the timescale of the complex relative to the national timescale UTC (SU) of ± 10 ns.
    • An optical ground-based frequency reference on cold strontium atoms was developed with an uncertainty of reproduction of the frequency unit and time of no more than 1 · 10-17 .
    • A keeper of time and frequency units was developed on the basis of a “fountain” of rubidium atoms having a frequency instability of no more than 2 · 10-16 for equipping the standards of time and frequency units and subsequent transmission of more accurate time-frequency information to precision ground and onboard equipment and GLONASS systems.
    • A developmental prototype of the national timescale storage complex of the Russian Federation was developed on the basis of a new generation of hydrogen keepers.

    The application of the newly developed technical equipment made it possible to significantly reduce the maximum displacement of the national timescale relative to the International Coordinated Time Scale (UTC), which in 2020 was less than ± 3 ns (FIGURE 2). The UTC (SU) timescale ranks among the best national implementations of UTC, according to the International Bureau of Weights and Measures (BIMP).

    Figure 2. Displacement of national timescales relative to Universal Coordinated Time (UTC). (Image: VNIIFTRI FSUE)
    Figure 2. Displacement of national timescales relative to Universal Coordinated Time (UTC). (Image: VNIIFTRI FSUE)

    Many important events are coming for GLONASS users in 2022. They will improve the user characteristics and lay the foundation for further development of the system.

    Sergey Karutin is general designer of the Russian GNSS program GLONASS.

    Nicolay Testoedov is CEO of JSC Information Satellite Systems Reshetnev (ISS JSC), a Russian satellite manufacturing company.

    Sergey Donchenko is general director of the Federal State Unitary Enterprise, Russian metrological institute of technical physics and radio engineering, VNIIFTRI FSUE.

  • Directions 2022: BDS enters new era of global services

    Directions 2022: BDS enters new era of global services

    Yang Changfeng is BeiDou’s Chief Architect. (Photo: BeiDou Navigation Satellite System)
    Yang Changfeng is BeiDou’s Chief Architect. (Photo: BeiDou Navigation Satellite System)

    Construction of the BeiDou Navigation Satellite System (BDS-3) has been completed. The system was formally commissioned on July 31, 2020. In 2021, BDS continued to improve performance, expand applications and deepen cooperation, and has achieved sustained, stable and rapid development.

    System Performance and Services

    Currently, 45 BDS satellites are operational in orbit — 15 BDS-2 satellites and 30 BDS-3 satellites jointly provide seven types of services to users. Specifically, for the entire planet, the system provides three services:

    • Positioning, navigation and timing (PNT).
    • Global short-message communication.
    • International search-and-rescue (SAR) services.

    For the Asia-Pacific region, the system provides four additional services:

    • Satellite-based augmentation.
    • Ground-based augmentation.
    • Precise point positioning.
    • Regional short-message communication services.

    The system has been operating continuously and stably since commissioning, with the average value of satellite availability better than 0.99 and the average value of satellite continuity better than 0.999.

    PNT Service. As actually measured by the International GNSS Monitoring and Assessment System (iGMAS), the global horizontal positioning accuracy is about 1.52 meters, the vertical positioning accuracy is about 2.64 meters (B1C signal single frequency, 95% confidence), the velocity measurement accuracy is better than 0.1 m/s, and timing accuracy is better than 20 nanoseconds. The performance is better in the Asia-Pacific region.

    FIGURE 1 shows the number of visible BDS satellites worldwide at BDT 00:00 on Nov. 18, 2021. Among them, the number of visible BDS satellites exceeds 20 in some areas of the Asia-Pacific region.

    figure 1. Number of visible BDS satellites, elevation ≥5° (2021/11/18/00:00 BDT). (CREDIT: www.csno-tarc.cn)
    Figure 1. Number of visible BDS satellites, elevation ≥5° (2021/11/18/00:00 BDT). (CREDIT: www.csno-tarc.cn)

    Global Short Message Communication Service. Trial service is provided through 14 medium-Earth-orbit (MEO) satellites for authorized users and low-orbit satellites, with a maximum single-message length of 560 bits, equivalent to about 40 Chinese characters.

    Search-and-Rescue Service. A COSPAS/SARSAT-compliant MEOSAR service is provided by six payloads deployed on six MEO satellites. A B2b signal-based Return Link Service (RLS) is provided through 24 MEO and three IGSO satellites, which have completed testing and verification and are in the process of coordination within the framework of COSPAS-SARSAT.

    Satellite-Based Augmentation Service. China’s Civil Aviation Administration is organizing satellite-ground integrated test and evaluation, and the positioning accuracy, alarm time, integrity risk and other indicators meet the requirements.

    Ground-Based Augmentation Service. Real-time centimeter-level and post-processing millimeter-level services are provided for industrial and public users, based on the regional network reference stations built in China.

    Precise Point Positioning Service. PPP signals are broadcast by three GEO satellites. The measured horizontal positioning accuracy is 0.24 m, the vertical positioning accuracy is 0.41 m (95% confidence), and the convergence time is less than 20 minutes.

    Regional Short Message Communication Service. The short-message communication function has been tested and verified for integration into public mobile phones; large-scale application is planned.

    Development of the Applications Industry

    Large-scale applications of BDS have entered a critical stage of liberalization, industrialization and internationalization. The overall output value of China’s satellite navigation and location-based service industry continued to grow in 2020, up to 403.3 billion yuan (US$63.2 billion), which is about 16.9% more than its value in 2019. In terms of BDS-3-enabled basic products, an industrial chain is gradually maturing, comprised of BDS/GNSS basic chips, modules, boards, antennas and other components.

    The certification and testing system of basic BDS products has been established and implemented. BDS is already supported by most mainstream chips. BDS is increasingly being integrated into the daily life of the general public. It is becoming the standard configuration for positioning functions of smartphones and other mass-market products.

    Smartphone manufacturers such as Xiaomi, Huawei, Apple and Samsung already support BDS. In the first three quarters of 2021, among all types of smartphones applying for online access in China, 72.3% supported positioning function based on BDS, accounting for 93.5% of the total sales volume. The BDS ground-based augmentation function has been introduced into smartphones to achieve high-precision positioning at the 1-meter level; lane-level navigation is being piloted in several cities in China.

    In terms of industrial applications, BDS has fully served multiple industries including transportation, public security, disaster relief, agriculture, forestry, animal husbandry and fishing. It has accelerated the integration into electricity, finance, communications and other infrastructure. In particular, in the fight against COVID-19 through scientific and technological approaches, BDS-based precise positioning has facilitated the efficient supply and circulation of anti-epidemic materials.

    BDS-based solutions for land rights determination, precision agriculture and smart ports have served the economic and social development of countries in Asia, Eastern Europe and Africa, and BDS-based products have been applied in more than half of the world’s countries and regions.

    International Cooperation

    BDS has always adhered to the development concepts of openness, cooperation and resource sharing; actively carried out practical international exchanges and cooperation; and contributed to China’s peaceful use of outer space.

    Bilaterally, the Eighth Meeting of the China-Russia Project Committee on Major Strategic Cooperation in Satellite Navigation was held in October 2021. Both sides jointly formulated and signed the Roadmap for Cooperation in the Field of Satellite Navigation from 2021 to 2025, providing planning and guidance for China-Russia satellite navigation cooperation in the next five years. Also, China’s Satellite Navigation Office signed a memorandum of understanding on satellite navigation cooperation with the National Committee on Space Activities of the Republic of Argentina and the South African National Space Agency, and formally established a regular cooperation mechanism.

    BDS is gradually being integrated into international standards, and is steadily promoting ratification by international standards bodies, including in the civil aviation, maritime, SAR, mobile communications and electrotechnical fields. Several international standards supporting BDS have been released. The Chinese government has drafted a letter of commitment to the International Civil Aviation Organization (ICAO), stating that BDS will provide basic services free of charge to civil aviation users around the world. The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) has officially issued a standard that ratifies BDSBAS, so that global marine users can carry out applications based on it. The Third Generation Partnership Project has started the standardization of BDS-3’s B2a and B3I signals. In the detection standard for Indicating Radio Beacon Locator of the Global Maritime Distress and Safety System issued by the International Electrotechnical Commission, BDS receivers and BDS-based SAR services will be supported.

    The Chinese government is steadily advancing the rule of law, attaching great importance to and comprehensively promoting the rule of law for satellite navigation. A legal system on BDS has been formed, consisting of national policies, industrial and local policies and regulations, and more. The legislative process of the Satellite Navigation Regulations of the People’s Republic of China has been actively promoted to ensure the healthy, rapid and sustainable development of the satellite industry. In May 2021, China issued a development report on the rule of law of BDS.

    Follow-Up Plan

    In the future, on the one hand BDS will ensure stable operation, while on the other hand it will focus on the development of backup satellites, and complete the production, state optimization and ground testing of backup satellites. Backup BDS-3 satellites with better performance will be launched as needed to further improve the reliability of the constellation. By adhering to the development concept of “BDS is developed by China, dedicated to the world and aiming to be first class,” carrying forward the BDS spirit of the new era of “independent innovation, open integration, unity of all, pursuit of excellence,” BDS will serve the world and benefit all humankind.

    • Number of BDS-3 satellites in orbit: 30
    • Signals broadcast: B1I, B3I, B1C, B2a, and B2b

    Yang Changfeng is chief architect of the BeiDou Navigation Satellite System and a Chinese Academy of Engineering academician.