China has launched two satellites into medium-Earth orbits (MEO) for its BeiDou Navigation Satellite System, according to the China Satellite Navigation Office.

The satellites were carried by a Long March 3B rocket from the Xichang Satellite Launch Center in Sichuan province and are the 13th group of third-generation BeiDou satellites operating in MEO.

The two spacecraft will start formal operation after a period of in-orbit technical verification, according to the China Satellite Navigation Office.

BeiDou is China’s largest civilian satellite system and one of four global navigation networks, along with the United States GPS, Russia’s GLONASS and the European Union’s Galileo.

Since 2000, a total of 62 BeiDou satellites, including the first four experimental ones, have been lifted on 46 Long March 3 series rockets from Xichang.

In June 2020, the final satellite to complete Beidou’s third-generation network was lifted by a Long March 3B rocket launched from the Xichang center. The following month, the system was declared complete and began providing full-scale global services.

Nearly 50 Beidou satellites in active service, including the latest pair.

SiTime Corporation, a precision and timing company, has released its Endura Epoch Platform. The platform is designed to provide robust and resilient positioning, navigation and timing (PNT) services critical in defense operations.

The MEMS oven-controlled oscillator (OCXO) can boost the resilience of PNT systems and other equipment, including radars, field and airborne radios, satcom terminals and avionics against spoofing, jamming and other disruptions in GPS signals.

Building off of the Epoch Platform launched in September 2023, the Endura Epoch MEMS OCXOs are designed to meet the challenging shock and vibration conditions found in aerospace and defense. These devices are manufactured using proven semiconductor processes that deliver the reliability and quality expected from silicon devices that cannot be achieved by quartz crystal OCXOs, especially in extreme conditions.

The Endura Epoch Platform MEMS OCXO greatly simplifies timing system design due to superior performance and delivers a significant improvement in size, weight and power (SWaP). Key features and benefits compared to quartz crystal OCXOs include:

• Programmable frequencies from 10 to 220 MHz
• Rated at 20,000 g shock survivability
• Up to 20 times better frequency stability over temperature
• Up to 3 times better Allan deviation, a measure of short-term frequency stability
• Surface-mountable, small footprint and low height 9.0 mm x 7.0 mm x 3.6 mm
• Low weight of 0.35 g
• 420 mW steady state power

Deep Sand Technology (DST), an autosteering and precision agriculture company, and the GEODNET Foundation have partnered to bring precision agriculture real-time kinematic (RTK) services to rural North America.

GEODNET-compatible RTK bases will be immediately available, which support centimeter-accurate operations without the need to install an ultra-high frequency (UHF) radio link.

The partnership between DST and GEODNET aims to offer affordable high-accuracy RTK-based GPS access into key U.S. agricultural and rural areas for precision agriculture, advanced cruise control systems, automated highway trucking operations and eco-friendly robotic lawnmowers.

The GEODNET RTK network comprises more than 3,600 stations globally, covering over 1,800 cities in 100+ countries as of 2023.

Topodrone has launched the PT61 camera, a thermal mapping solution designed for UAVs. The camera system aims to provide users with detailed thermal orthomosaic maps and accurate 3D models. Developed in partnership with Agrowing, the PT61 is a versatile tool aimed at meeting the growing demand for multispectral data collection in renewable energy and other domains, the company said.

The PT61 combines a 61-megapixel camera with integrated thermal imaging capability. It can also switch between RGB and multispectral modes. When integrated with Agrowing’s multispectral lenses, the camera offers detailed data across 10 spectral bands and an infrared band ideal for professionals in solar plant inspection and dam management.

The system can also be used in urban mapping, energy efficiency assessment and disaster management. The Topodrone post processing software complements the hardware by streamlining remote sensing tasks to offer surveyors and researchers high levels of efficiency.

“Seen & Heard” is a monthly feature of GPS World magazine, traveling the world to capture interesting and unusual news stories involving the GNSS/PNT industry.

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Drawing with GPS

According to Guinness World Records, a 982.53-mile, seven-day ride by David Schweikert was the “largest GPS drawing by bicycle”. His drawing of a cross spanned three U.S. states: Wisconsin, Nebraska and South Dakota. “GPS drawings,” or Strava art, are growing in popularity, with two other notable record attempts being made in the past 12 months. Schweikert completed his ride in May, but for Guinness World Records to consider a record official all documentation and data must be verified. There are also strict rules and regulations relating to mileage that deviates from the course. To stick strictly to the profile of the cross, Schweikert rode 35% of his trip on unpaved roads.

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Location Data and Accountability

The Connecticut State Police is under fire for failing to archive vehicle location data. While all police cruisers are equipped with location technology, only live data is available, reported CT Insider. Officials can locate a police cruiser when the vehicle is in use but cannot determine where it has been in the past. Experts and lawmakers told CT Insider that not archiving location data for some period of time is unusual, and they are worried that it could make it harder to hold troopers accountable when their conduct comes into question — including in multiple ongoing investigations examining allegations of ticket falsification within the force.

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Collars and Cats

The Saving Wildcats conservation project, based at Cairngorms National Park in the Scottish Highlands, is using tracking collars to study endangered wildcats. For the project, 19 wildcats were released into the park while a field research team monitored movement data and was alerted if any of the animals were hurt or killed. This project is a collaboration between the Royal Zoological Society of Scotland (RZSS), NatureScot, Forestry and Land Scotland, and the Cairngorms National Park Authority. The new kittens, born at RZSS’s Highland Wildlife Park, will be released into the wild next summer once they are aged six to eight months.

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High School Launches Weather Balloons

Croydon High School, in partnership with the University of Bath, has completed the Astrogazers project, which involved launching a weather balloon into space. On September 12, a team of girls from grades 5 through 11 successfully launched two meteorological balloons that ventured to an altitude of 32,380 m. The balloons carried essential equipment, including cameras, data loggers and GNSS receivers — all designed to explore how different materials respond to atmospheric conditions.

It may be hard to remember — or imagine — life without the Global Positioning System (GPS). From finding the nearest Dunkin’ Donuts to making ATM withdrawals, GPS is part of everyday life. It makes global finance possible, first responders faster, electric grids smarter and industries more efficient. Without GPS, the critical infrastructure that powers homes and workspaces, mobilizes roads and rails, guides air travel, delivers news and even produces food could come to a grinding halt. That fact is not lost on the United States’ adversaries.

Modernizing GPS to make it work better in times of peace and to ensure its resilience in times of conflict is a prime responsibility of the Space Systems Command (SSC) of the U.S. Space Force (USSF).

History

When it comes to anniversaries, 2023 is a big year for GPS.  It’s widely considered to be the 50-year anniversary of GPS because it was on December 17, 1973, that the Defense Systems Acquisition Review Council (DSARC) gave U.S. Air Force Col. Bradford Parkinson, now retired and hailed as the father of GPS by many in the aeronautics and astronautics sectors, approval to proceed with development of what would become today’s 31-satellite GPS constellation.

It also marks 40 years since President Ronald Reagan authorized the use of GPS for civil aviation following the downing of Korean Air Lines Flight 007, after it inadvertently entered hostile air space. This year is also GPS’s 30-year anniversary of initial operating capability and the 20-year anniversary of the Federal Aviation Administration (FAA) Wide Area Augmentation System (WAAS), which enhances the accuracy and integrity of GPS services across the entire National Airspace System.

At the most recent meeting of the Civil GPS Service Interface Committee, the recognized worldwide forum for effective interaction between civil GPS users and GPS authorities, Parkinson — who, after his service in the U.S. Air Force earned a Ph.D. and has been a professor at Stanford University for decades — recounted his first-hand experience making GPS a reality. The former chief architect for GPS, who led original advocacy for the system as an Air Force colonel, described the incredible challenges and numerous unique innovations involved in starting this program.

Today’s GPS continues to deliver on its commitments for accuracy, integrity, availability, continuity and coverage. It is considered by many the gold standard in navigation and timing. Yet challenges remain, posed by an increasingly contested space domain and emerging threats from pacing challengers and adversarial nations. Advancing, maintaining and modernizing the GPS enterprise for the benefit of commercial, civil and military users falls under the responsibility of SSC and is carried out by the field command’s Military Communications and Positioning, Navigation & Timing program executive office (SSC/MilComm & PNT), in collaboration with its exceptional mission partners, and launch services provided by SSC’s Assured Access to Space program executive office.

As we celebrate the multiple GPS anniversaries, it is worth exploring successes in GPS modernization. This update will explore the exciting advancements in the GPS space systems, user equipment, and control systems.

Space Systems

On January 18, the Lockheed Martin GPS III Space Vehicle 6 (SV06) launched into orbit aboard the SpaceX Falcon 9 Block 5 rocket out of Cape Canaveral, Florida. The successful launch of SV06 and handoff to the USSF’s Space Operations Command/Space Delta 8/2nd Space Operations Squadron marked another key step in the larger goal of modernizing the GPS constellation. SV06 is the sixth GPS III satellite to be launched and is equipped with the full suite of modernized signals and capabilities. The GPS III satellites are more capable and resilient than their predecessors. Improvements include three times greater accuracy and up to eight times improved anti-jamming capabilities.

In preparation for future launches, the GPS III team has been diligently working with the Assured Access to Space Launch Enterprise to ensure rigorous and successful integration of the GPS III spacecraft’s launch systems onto a brand-new rocket, the United Launch Alliance Vulcan Launch Vehicle. GPS III SV07/Vulcan is targeted for launch in the summer of 2024.

Additionally, production of the tenth and final space vehicle in the GPS III fleet was finalized this year and it has a target launch date of 2026. GPS III Space Vehicles 7-10 are in storage and available for launch, awaiting launch call-up.

The modernization, however, doesn’t end there. GPS IIIF continued to make progress this year with development and integration of the follow-on spacecraft program with 10 vehicles now in production. GPS IIIF Non-Flight Satellite Testbed completed panel integration and initial system performance testing and the program completed an integrated baseline review. The GPS IIIF team worked with the National Security Agency to successfully complete an information assurance preliminary design review, one of the first such reviews of its kind. The team has also made essential inputs to the planning for the future GPS IIIF launch and checkout capability.

User Equipment

SSC/MilComm & PNT actively manages and maintains the public GPS interface specifications that allow industry to build civil receivers that successfully capture and process the GPS signal-in-space satellite-broadcast. Simultaneously, SSC also leads design and development of military receivers, currently the Military GPS User Equipment (MGUE). In April, the MGUE Increment 1 team successfully completed technical requirements verification on its MGUE GPS receiver application module — a standard electronic module specifically designed for aviation and maritime users. This allowed the MGUE Inc 1 program to deliver its new aviation and maritime software to the U.S. Air Force and U.S. Navy to support the lead platform integration and testing on the B-2 Spirit bomber and the Arleigh Burke guided-missile destroyer. This is the first fully functional GPS aviation and maritime software suite to support the jam-resistant military M-code signal.

GPS has an active and successful foreign military sales (FMS) program with 60 allied partners, and many of them are highly engaged with SSC/MilComm & PNT to acquire MGUE receivers with their M-code capabilities. According to the Department of State, U.S. allies and partners purchase approximately $45 billion annually in arms, equipment, and training — many equipped with GPS — via FMS.

This spring, the MGUE Increment 2 team, developing an advanced, follow-on receiver, completed the new Next Generation Application-Specific Integrated Circuit (ASIC), the first of two major Critical Design Reviews (CDRs) with mission partner BAE Systems. That success was followed by a second CDR this summer for the MGUE Increment 2 Miniature Serial Interface (MSI) receiver card, which integrates the Next Generation ASIC along with a host of other innovations. L3Harris, a mission partner, has also successfully completed its own next generation ASIC CDR and is on-track for an MSI CDR in October. MGUE Increment 2 also awarded a Joint Modernized Handheld contract to the Technology Advancement Group, enabling this industry partner to move forward on its MGUE Increment 2 Handheld initiative.

Control Systems

While the current operational control system continues performing at a high level, a major update to the GPS modernization architecture is underway. In March 2022, the USSF began formal testing of the Next Generation Operational Control System (OCX) Block 1/2 system through the Functional Qualification Test designed to test OCX requirements. Currently, preparations are underway to follow that up with a major government-led Integrated Systems Test.

OCX developmental testing is an important part of the software development process. Thorough developmental testing can help ensure that OCX is of high quality and meets all requirements. Testing is rigorous and comprehensive; it is a complex and challenging undertaking, but one necessary to ensure OCX is ready for operational use before it is transitioned into service.  SSC’s program office is taking the necessary steps to ensure that it will be a success.

The OCX 3F program also contributes to SSC’s advancements in GPS control systems. The follow-on to OCX for support to GPS IIIF spacecraft has successfully completed a Critical Capability Release for the GPS IIIF launch and checkout capability.

Sustainment

SSC/MilComm & PNT’s GPS Support Delta has a legacy of providing sustainment expertise for Space Operations Command’s operations team. It sustains a global network including a Master Control Station (MCS), Alternate MCS, 11 command-and-control antennas, and 16 monitoring sites, plus 38 on-orbit GPS spacecraft. The sustainment team performs seamlessly, anticipating issues, collaborating with operators, updating servers and software tools, enhancing cyber secutiry and fine-tuning GPS to keep it running at peak performance.

Future Opportunities

In 2019, the department of the Air Force designated the Navigation Technology Satellite-3 (NTS-3) as a Vanguard program and the Department of Defense’s first experimental integrated navigation satellite system in nearly 50 years. Co-sponsored by SSC and the Air Force Research Laboratory, NTS-3 is helping to pave the way for more robust and resilient positioning, navigation, and timing.

In June, SSC/MilComm & PNT hosted its first Alternate/Augmented PNT Reverse Industry Day at SSC’s new Commercial Space Marketplace for Innovation and Collaboration Center. The event was a unique opportunity for government leaders and technical experts to hear directly from industry in a one-on-one environment about their many exciting innovations and opportunities as well as challenges. SSC was joined by its close government and interagency partners, including representatives from the Department of Transportation, the National Space-Based PNT Coordination Office, the Space Operations Command/Mission Area Team, the Air Force Research Laboratory, and the Space Development Agency. Through the event, SSC gained market intelligence and made many valuable industry connections for future investments.

Conclusion

As the nation celebrates an exciting 50-year anniversary of GPS, continued enhancements in the three elements of the GPS enterprise — space systems, user equipment, and control systems — represent significant milestones toward GPS modernization. This essential upgrade is delivering many new GPS capabilities — including robust new signals such as M-code, L2C, L5, and L1C — while preserving backward compatibility for GPS legacy signal users. GPS modernization will enhance utility, make the system more robust and resilient, and ensure that the United States, its allies, and its government agency partners have access to the most accurate and reliable navigation and timing services available. At the same time, while we continue to look for ways to (in the words of the National Space-Based PNT Advisory Board) “protect, toughen, and augment” GPS capabilities, we are also actively engaged in evaluating ways to incorporate alternate sources of PNT, as well as GPS augmentation, that will continue to make PNT capabilities even more robust and resilient in the future.

Over the past year, the BeiDou Navigation Satellite System (BDS) has been continuously striving for world-class excellence throughout its development, especially in the system operation and the development of applications and new technologies. With this relentless innovation and pursuit of excellence, BDS continues to surpass its benchmarks.

System Operation and Services

The establishment of an on-orbit support system and the enhancement of on-orbit operational controls, combined with in-orbit software reengineering and real-time ground diagnostics, have significantly improved BDS’s functionality and service performance. Both space and ground segment operational statuses are regularly evaluated within the engineering framework. Various data sets and schemes are rigorously tested and reviewed to ensure the utmost level of user satisfaction.

In addition, the system integrates new techniques, such as joint satellite-to-ground and inter-satellite control, unified information transmission and coordinated processing of observation data. Combined with artificial intelligence, cloud platforms and big data analytics, the continuous global monitoring and assessment capability for BDS/GNSS has been upgraded.

In May, the first BDS-3 GEO backup satellite was successfully launched. Currently, BDS operates a total of 46 satellites in orbit, comprising 15 in the BDS-2 constellation and 31 in the BDS-3 constellation. Since its official commissioning, BDS has been consistently providing reliable services with steadily improving performance metrics. Data from the International GNSS Monitoring and Assessment System (iGMAS) in 2023 indicate that the BDS space signal availability is 100%, signal continuity is 99.996%, and the global positioning accuracy is 5 m, with notable enhancement observed specifically within the Asia-Pacific region. Figure 1 shows the positioning accuracy of the BDS B1C signal assessed with global monitoring stations. Figure 2 shows the number of visible BDS satellites, with a minimum of six to eight satellites consistently in view globally.

BDS remains committed to serving the global community and benefiting humanity by promoting innovations that seamlessly integrate the fundamental positioning, navigation, and timing functions of the system, while building four major service platforms to support the development of BDS distinctive service applications. The International Search and Rescue Service Platform provides MEO search and rescue services that comply with COSPAS-SARSAT standards and offer BDS-based characteristic return link services. The satellite-based augmentation system (SBAS) service platform provides the single-frequency augmentation service using the B1C signal in accordance with APV-I requirements as well as the dual-frequency augmentation service using the B2a signal in accordance with CAT-I requirements. The short message service platform achieves seamless integration with terrestrial mobile communication systems and the Internet, marking a breakthrough in enabling smartphones to connect directly to satellites and bringing regional short message communication services to mainstream smartphone users. The ground-based augmentation service platform has a nationwide network of ground stations and provides high-precision positioning augmentation services in real time, with accuracy levels ranging from meters, to decimeters, to centimeters and even to millimeters for post-processing, to meet the needs of various industries and the general public.

System Applications and Industrialization

The BDS application industry has experienced sustained growth. In 2022, China’s satellite navigation and location-based service industry reached a total output value of RMB 500.7 billion (approximately $71.5 billion USD). A complete industrial chain has been established, including chips, modules, antennas, boards, receivers and comprehensive services.

The basic BDS products have been continuously developed and have reached a production scale of hundreds of millions. In 2022, the sales of in-car navigation devices in China exceeded 12 million units. Sales of various receivers, including those for IoT, wearables, vehicles and high-precision equipment, exceeded 100 million units. Intensive research and development efforts are underway to integrate BDS navigation capability with inertial, mobile communication and visual navigation methods to enhance the user experience in various application scenarios.

BDS is extensively used in a wide range of sectors and is proving to be a key technological driver of socio-economic growth. In the transport sector, more than 7.9 million road vehicles, more than 40,000 postal and express delivery vehicles, more than 47,000 ships, more than 13,000 aids to navigation on waterways and nearly 500 general-purpose aircraft use BDS.

In agriculture, forestry, livestock and fisheries, more than 100,000 autonomous agricultural machine units, more than 20,000 intelligent livestock tracking collars and more than 100,000 fishing vessels are equipped with BDS receivers. In the water resource management area, the BDS Short Message Service supports hydrological monitoring of more than 2,500 reservoirs. In digital construction, the synergy of BDS with multi-sensor and Internet technologies has proven essential for projects such as the Chengdu-Kunming Railway, the Shenzhen Mawan Undersea Tunnel and the Xinjiang Desert Highway, significantly improving construction quality and efficiency while reducing labor and material costs.

Significant progress has been made in consumer applications. In 2022, 260 million of the newly registered smartphones in China supported BDS, accounting for 98.5% of the total. The BDS short message service has been seamlessly integrated into mainstream smartphones, eliminating the need to change SIM cards, phone numbers or add external devices. Consumers can now access BDS-3’s short message services. BDS-based lane-level navigation has been piloted in eight cities in China, with nationwide deployment planned. BDS-enabled features such as “Dynamic Traffic Light Countdown” and “Traffic Light Status” have covered millions of traffic signals in China, with daily signal queries exceeding 1.4 billion. Moreover, prominent domestic on-line mapping service providers deliver BDS satellite positioning service hits more than 300 billion times daily.

International Cooperation and Exchange

China has strengthened bilateral partnerships to expand cooperation initiatives. In March 2023, the China-Russia Satellite Navigation Major Strategic Cooperation Project Committee was upgraded to the China-Russia Satellite Navigation Cooperation Subcommittee, which held its inaugural meeting in October. The fourth China-Arab States BDS Cooperation Forum was successfully convened in October. Active participation in international events under multilateral organizations such as the United Nations and academic exchanges in the field of satellite navigation have promoted joint discussions on global satellite navigation, ensuring the compatibility and interoperability of navigation satellite systems worldwide.

China has promoted the integration of BDS into international standards set by sectors including civil aviation, maritime, mobile communication, as well as search and rescue. In November 2022, the BDS Short Message Service System became the third global satellite communication system for maritime distress and safety, as recognized by the International Maritime Organization (IMO). In June 2022, the technical standards for BDS B2a and B3I signals were approved by 3GPP, leading to the formal release of BDS-assisted positioning standards for fourth- and fifth-generation mobile communication systems. In November 2022, China officially became a space segment provider for COSPAS-SARSAT.

Intensive efforts have been made to create an enabling “soft environment” through policymaking, standardization and IPR protection to maintain open communication and sustainable development. With the release of “The BeiDou Satellite Navigation Standard System (version 2.0)” in 2022, China has submitted more than 7,000 patent applications related to satellite navigation, underscoring its commitment to innovation and high-quality development. In November 2022, the Information Office of the State Council of China released a white paper entitled “China’s BeiDou Navigation Satellite System in the New Era,” which captures BDS’ transformative journey: unveiling new service capabilities, driving industrial growth, promoting collaborative initiatives and charting future paths.

In April, the 13th China Satellite Navigation Conference was successfully held under the theme “Digital Economy —Intelligent Navigation.” For the first time, challenges related to satellite navigation and positioning, navigation and timing (PNT) systems were solicited and later published on the official BDS website. These challenges cover current and emerging GNSS technologies, services and applications, including the establishment and maintenance of GNSS satellite-based spatial-temporal reference services, the provision of high-precision navigation and timing services in lunar space, the provision of accurate positioning services in complex environments, and the deployment of intelligent applications. In addition, proposals were made to develop a unified theory of multi-source heterogeneous spatial-temporal information for PNT applications, aiming to further integrate BDS, PNT and other new information technologies.

Prospects of Future Development

In the future, two to four backup satellites are scheduled to be launched to strengthen the robustness and accessibility of the BDS constellation. Commitments have also been made to continuously raise the standards of intelligent BDS ground operations and maintenance to ensure stable operation and performance improvement. In addition, system management and routine assessments will be strengthened, with a comprehensive strategy for both space- and ground-based operations to optimize the operational ecosystem and enrich BDS services and user experience.

In the area of emerging technologies, research on improving navigation with low-Earth orbit technologies, as well as its practical applications, will be further promoted to strengthen the precision and integrity of the system and to meet the requirements of an era characterized by ubiquitous connectivity and intelligent devices. Efforts will also include studies on multi-layer space constellations and the fundamentals of lunar space navigation to extend the coverage of BDS services. In addition, research will continue on satellite-based autonomous timekeeping technologies and pulse star technologies, with the aim of establishing and maintaining GNSS satellite-based spatial-temporal reference systems.

With the fundamental philosophy of “independent innovation, open integration, unity of all, and pursuit of excellence” in mind, the integration of BDS with innovative realms such as 5G, artificial intelligence, and big data will be accelerated steadfastly, aiming to shape a national PNT system that’s more ubiquitous, integrated, and intelligent by 2035.

The vast cosmic arena beckons for collaborative exploration. BDS will remain anchored to its mission. BDS is developed by China, dedicated to the world and strives to be first class. With a resolute ambition to promote progress, BDS strives to make significant contributions to the development of human society and a community with a shared future for mankind.

GLONASS remains a core of Russia’s positioning, navigation and timing (PNT) system and is utilized by people around the world. Annual shipments of new GLONASS/GNSS receivers for the communications, transport, agriculture and power industries exceed 25 million units in Russia alone. These users are interested in continuously increasing the quality of PNT primarily based on the improvement of the basic service radio navigation field generated by the GLONASS space complex.

This space complex consists of the constellation comprising medium-Earth orbit (MEO) satellites, the modernized ground control complex and the ensemble of user equipment. The current constellation consists of 26 satellites comprising three generations and five modifications. For the past 15 years, GLONASS-M has been the core satellite and now the constellation includes 21 of them. The fact that 14 of them successfully function beyond their guaranteed active lifetime verifies their high reliability. They are steadily being replaced with GLONASS-K satellites, of which there are already four in the constellation. Along with GLONASS-K launches, the in-orbit testing of the first GLONASS-K2 satellite was initiated on August 7, 2023.

Since the launch of the first GLONASS satellite, the navigation signals have changed significantly. Initially, each of 24 GLONASS satellites transmitted the signals with its own separate carrier frequencies in the L1 and L2 bands (Figure 1). The total bandwidth of the registered GLONASS satellite network was 23.72 MHz in L1 band and 20.72 MHz in L2 band, respectively.

In 1995, the Russian Federation assumed obligations to protect the band used in radio astronomy in the search for extraterrestrial life. At the first stage (until 1998), the broadcast of the navigation signals in the carrier frequency channels 16-20 was terminated and the frequency channels 13, 14, 20 and 21 were used under exceptional circumstances (Figure 2). Then, all newly launched satellites transmitted the signals only in the frequency channels 0-12. By 2005, the total bandwidth of GLONASS satellites was reduced to 16.97 MHz in L1 band and 15.47 MHz in L2 band respectively (Figure 3).

Starting in 2005, GLONASS satellites have been using the frequency channels from -7 to +6 (Figure 4) to broadcast frequency division multiple access (FDMA)  navigation signals. As a result, the upper limit of the GLONASS signal bandwidth in the L1 band dropped from 1620.61 to 1610.485 MHz and the lower limit went down from 1596.89 to 1592.953 MHz. The signal bandwidth in L2 band changed similarly.

The GLONASS-K2 satellite was developed to improve GLONASS user performance. The satellite broadcasts new code division multiple access (CDMA) signals in the above mentioned bands as well as in the L3 band. The first satellite of this batch was successfully deployed in orbit on August 7, and already started to broadcast the new CDMA signals. The radio telescope of Bauman Moscow State Technical University is used to monitor the broadcast signals to analyze the frequency and power characteristics of the satellite.

The radio telescope has a large-aperture fully rotatable antenna with a dish diameter of 7.75 m. It ensures that the width of the main lobe of the antenna’s pattern in 1.6 GHz band is 1.8° and the power amplification of the received navigation signals is 40 dB.

Primarily, users are interested in the new CDMA navigation signal on L1OC transmitted along with the conventional signal on L1OF. The joint group bandwidth of the FDMA signals with the carrier frequency 1598.625 MHz, which refers to the frequency channel -6, and the CDMA signals with the carrier frequency 1600.995 MHz is shown in Figure 5.

The exploitation experience of recently manufactured satellites in practice demonstrates that their operational capacity exceeds their planned lifetime by one and a half times. The final GLONASS-M satellite (No. 761) launched in the last year was manufactured in 2015. These circumstances make it possible to predict that the renewal of the whole constellation with new GLONASS-K2 satellites broadcasting the full ensemble of CDMA signals is likely to be finished by 2035.

In 2024, the renewal of the constellation will continue due to the launches of GLONASS-K satellites and another GLONASS-K2 satellite.

With the launch of the first GLONASS-K2 satellite accomplished, the Passive Quantum-Optical System (PQOS) is implemented on the base of Russian quantum-optical systems with a wavelength of approximately 0.5 nm. The PQOS ensures pseudorange measurements in the optical band. The elements of the system include specialized ground equipment to register moments of laser pulse emission by a ground laser station (ground PQOS) and specialized satellite payload equipment to register moments of the laser pulse reception onboard (onboard PQOS). Therefore, all GLONASS new generation satellites are capable of performing both conventional active (two-way) measurements and passive (one-way) measurements with the accuracy of timescale difference definition better than a nanosecond and based on the data of laser optical systems.

The processing of active and passive measurements gives an opportunity to get their difference combinations to compare timescales kept by onboard and ground frequency standards at a previously unachievable picosecond level of precision. The accuracy of PQOS results is sufficient to provide in-orbit tests of prospective new generation onboard frequency standards with a daily stability σ around 5×10-15.

The achieved accuracy level of PQOS results is also sufficient to calibrate measurement links for prospective GLONASS satellites, including links of active measurement systems, inter-satellite links and ionosphere-free linear measurement combinations conducted by passive measurement equipment based on FDMA and CDMA signals. The obtained results correspond to the world accuracy level in metrology and ensure the uniformity of measurements. The developed PQOS and technologies based on its measurements fully contribute to the effective metrological support for the tests and operation of the GLONASS space complex, including prospective GLONASS-K2 satellites and the ground complex.

Airbus is working with a team to develop a “hybrid” approach to electric aircraft, which means that their experimental aircraft is not only using electric power — with electric motors and propellors (propulsers), an 800-volt battery, and a hi-voltage distribution and control system. It also has a conventional turbine which supplies torque to a conventional propeller and generates electrical power to maintain charge for the 800-volt battery.

The team working with Airbus includes Daher, which has modified its TBM 900 turboprop aircraft to add the electrical system, motors and props supplied by Safran. Airbus has developed the 800-volt battery and the Flight Control System for the aircraft, through which any future autonomous capability would likely be brought about.

The decision to try this ‘hybrid’ approach may have been influenced by Volvo, which is pressing this approach for the Series 90 and 60 of its hybrid Electric Vehicles (EV). Combining recharging by an internal combustion engine with a battery and electric drive system greatly extends the range of this model, greatly reduces its gas consumption, and minimizes the hunt for rare recharging outlets.

It would seem that the principal benefit from the Airbus team development could be the 800-volt DC battery design, and the high voltage distribution/control/recharging system when they are potentially spun off and applied to other manned/unmanned eVTOL passenger aircraft. The basic problem for eVTOL aircraft is payload and range – is that something that a huge energy reservoir such as this battery system could support?

Developed by Airbus Defense and Space in Toulouse, France, the 800-volt DC battery system delivers up to 350 kilowatts to the electric system on the aircraft. The battery was derived from earlier versions that were flown on Airbus CityBus eVTOL demonstrator and FlightLab helicopters. The Lithium-ion battery weighs in at 350 kg (772 lbs.) and is mounted in an enclosure of the belly of the EcoPulse demonstration aircraft.

Airbus reportedly plans on taking this high energy-density battery into its commercial aircraft business. But the main market could be for hybrid eVTOL aircraft, which can carry this heavy battery and its control system and to benefit from the massive energy density.

Meanwhile, as the Russian-Ukrainian war drags on with both sides throwing at each other increasing numbers of ‘kamikaze’ UAVs carrying explosives, interest has recently been growing around a 2020 report out of St. Petersburg Electro-technical University in Russia that critiques the Russian air defense system. According to the report, these defenses are poorly adapted to detect or destroy vehicles as small and slow-moving as UAVs.

Ukrainian UAV troops were only recently pictured assembling weaponized drones for their one-way trip to Russian-owned targets.

The explosive carriers are frequently simple racing UAVs. In one released photo, an inexpensive quadcopter is taped together with plastic explosives and an RPG warhead using adhesive tape. Nothing has to be very durable, just durable enough to last for its short one-way trip through Russian defenses.

The Russian air defenses rely on several tracked and/or wheeled mobile systems using both guns and missiles. This includes radar-guided and heat-seeking missiles, such as the Pantsir-S1, the Tunguska, the Tor, the Strela-10, and the Igla-S man-portable missiles, all of which are designed to combat high-speed jet aircraft, helicopters, and cruise missiles. At the same time, UAVs are slow and very small in comparison.

Unfortunately, the missiles ‘ poor target detection capability and detonation control systems appear to be the culprits for the inability to strike down UAVs. Tor radar has been seen to only detect at 3-4km (1.8 -2.5 miles), while the minimum operating range is about the same. Thus, misses are reportedly more likely than taking out attacking drones. While the system may be somewhat ineffective, the cost of using missiles is huge.

A Ukrainian UAV recording within close range of a Russian Tor defense system has captured video of a missile hurtling past and failing to bring it down. Similar results have been found with both the Pantsir-S1 and Tunguska defense systems.

For the close-in gun and cannon defense systems, Russian tests demonstrated that to raise the probability of a direct hit to just 50% for an attacking drone at a distance of 1.3 miles, between four to 13 thousand shells would need to be fired.  This is significantly more ammunition than one Tor system can fire in one volley without reloading, even at 5,000 rounds/minute of which it is capable.

Ukrainian war strategists continue to acquire thousands of UAVs each month, while its troops continue to throw them against their Russian invaders with improvised explosive payloads. Meanwhile, as of December 2023, Congress is continuing negotiations over another $61.4 billion in funding to further Ukraine’s war efforts, even while President Zelenskyy visited Washington to urge the U.S. to maintain its support.

The problem with this situation is that both sides have learned that UAV warfare’ is simpler, less dangerous for the aggressor, and less costly than regular offensives. Thus, a stalemate might prolong the war for even longer.

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So, on the commercial, peaceful side of drone development, the possibility of a hybrid-electric approach for eVTOL passenger-carrying autonomous vehicles is making progress. Nevertheless, as the war continues in Ukraine, could the reduced cost of UAV warfare’ possibly prolong it?