Tag: November 2024

  • Seen & Heard: Self-driving cars get smarter, Antarctic Peninsula turns green and more

    Seen & Heard: Self-driving cars get smarter, Antarctic Peninsula turns green and more

    “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.


    Smarter self-driving cars

    Photo: hoi dongsu / iStock / Getty Images Plus / Getty Images
    Photo: hoi dongsu / iStock / Getty Images Plus / Getty Images

    Researchers at Drexel University have developed a testing method to enhance the robustness of autonomous driving systems. Their approach uses dynamic visual patterns to evaluate object detection capabilities in self-driving cars, focusing on critical objects such as traffic signs. A “Screen Image Transformation Network” (SIT-Net) simulates real-world image capture scenarios affected by environmental factors. By identifying weaknesses in autonomous vehicle perception systems, the researchers aim to improve safety and reliability in future self-driving technologies.

    Robo-dog gets an upgrade

    Photo: Boston Dynamics / Leica Geosystem
    Photo: Boston Dynamics / Leica Geosystem

    The Leica BLK ARC autonomous laser scanning module has become the first certified reality capture device capable of being fitted to Boston Dynamics’ robotic dog, Spot. The BLK ARC, when mounted on Spot, is designed for fully autonomous and repeatable scan missions. Users can plan scan paths remotely using existing drawings or BIM models, allowing the robot to navigate and capture data with minimal human intervention. Spot features a 360° vertical and 270° horizontal field of view, with a scan range of up to 25m.

    USGS aids recovery after Hurricane Helene

    Photo: Logan Combs, USGS
    Photo: Logan Combs, USGS

    The U.S. Geological Survey (USGS) is actively aiding recovery efforts following Hurricane Helene by collecting flood data, repairing damaged stream gages and analyzing new flood records. The agency has deployed its landslide event team to assess and document landslide impacts, conduct aerial surveys and map affected areas. By collaborating with local, state and federal agencies, the USGS is providing critical data and expertise to support disaster response and recovery efforts.

    Antarctic Peninsula turns green

    Photo: Tom Roland
    Photo: Tom Roland

    Satellite imagery revealed that the Antarctic Peninsula is experiencing a dramatic increase in vegetation, with plant coverage expanding from less than 1 km² in 1986 to nearly 12 km² by 2021. This trend has accelerated significantly, coinciding with extreme heat events and record glacier melting linked to climate change. The study, conducted by researchers from the Universities of Exeter and Hertfordshire and the British Antarctic Survey, indicates that warmer temperatures and increased precipitation create favorable conditions for mosses, which dominate the newly vegetated areas.

  • GLONASS in the age of hydrogen

    GLONASS in the age of hydrogen

    The development and digital transformation of the global economy are based today on high-precision time synchronization of transport management processes, the transmission of electricity and data and many other processes. The high-precision global synchronization of GNSS spacecraft signals makes global instantaneous all-weather navigation possible and is the primary solution to the problem of time transmission.

    For the past 57 years, since their adoption by the International Bureau of Weights and Measures (BIPM) as a unit of time measurement in the International System of Units of the Atomic Second, the technical characteristics of atomic frequency standards have increased significantly. The universally used Coordinated Universal Time (UTC) is based on the atomic time scale (AT), the readings of which are adjusted taking into account data regarding the Earth’s rotation.

    Since its inception, GLONASS has relied on basic solutions embedded in the definition of UTC(SU). AT is formed by calculating the total number of vibrations at the resonant frequency of the energy transition between the levels of the hyperfine structure of the ground state of the cesium atom (133Cs) in the absence of external influences. It was based on this substance that the first ground and airborne frequency standards for GLONASS were created.

    In accordance with the system’s interface control document, GLONASS transmits Moscow Time1, which is established by law by the Russian Federation. GLONASS transmits UTC(SU), which is formed as UTC+3 hours. In recent years, much work has been done to modernize the infrastructure for the formation of the national UTC(SU) time scale2. Today, the State Standard of Time and Frequency (SSTF) of the Russian Federation is one of the most modern time synchronization centers in the world. The basis of the SSTF are hydrogen frequency and time standards (HS) of the active type. The composition of the SSTF includes a storage complex of the national time scale based on the six newest active-type HS with a daily frequency instability of 3×10-16. In total, the SSTF consists of 18 HS.

    Including new HSs in the composition of the SSTF has led to a significant increase in its contribution to forming the UTC scale. Currently, 87 time standards at national time laboratories contribute to the formation of UTC, which, following the recommendations of the BIPM time department, regularly provides measurement information of standards of the established format and content. In turn, the BIPM time division forms the International Atomic Time Scale (TAI) and the UTC scale. On a monthly basis, the BIPM Time Department publishes the results of the international key comparisons CCTF-K001.UTC and other data based on which a comparative analysis of the metrological characteristics of national standards is carried out.

    The ALGOS algorithm is used for the formation of TAI and UTC2. It includes two main procedures: forecasting the drift of the frequency of standards and determining the contribution of specific standards to the final result — determining the statistical weight of standards.

    Figure 1: Dynamics of the contribution of the world’s major time laboratories. (All figures provided by the authors)
    Figure 1: Dynamics of the contribution of the world’s major time laboratories. (All figures provided by the authors)

    Starting in September 2011, forecasting of the standards’ frequencies takes into account the frequency drift inherent in hydrogen frequency standards. The procedure for determining the statistical weight of standards was also changed; preference was given to the predictability of their frequency, which showed a more balanced distribution of statistical weights and increased the contribution of hydrogen standards to the formation of TAI and UTC.

    Figure 1 shows the dynamics of the contribution of the world’s main time laboratories to the formation of UTC for 2022-2024: Russia – the Main Metrological Center of the SSFT, SU; United States – Naval Observatory, USNO; China – National Time Service, NTSC; Japan – National Institute of Information and Communication, NICT; France – Paris Observatory, OP; Sweden – Technical Research Institute, SP; Germany – Institute of Physics and Technology, PTB; Poland – Time Laboratory, PL. The WT contribution of each laboratory is calculated as the sum of the weights of all frequency standards, the measurement results of which this laboratory transmits to the BIPM. The weight of each individual atomic time and frequency standard is calculated monthly by the BIPM time division when calculating TAI and UTC based on an assessment of its frequency stability over the billing period.

    The main characteristic of the HS, which affects the characteristics of the formation of time scales, is the instability of the frequency of the output signals. To quantify the frequency instability of the output signals, a number of characteristics are used that reflect both random and systematic frequency changes over time. The Allan variation has been widely used for more than 50 years as the main assessment of the frequency instability of the output signals of standards in the time domain.

    At the same time, in terms of frequency instability, the SSTF atomic clock also occupies a leading position. In October 2022, the average weight of atomic clocks of laboratories in the formation of TAI and UTC increased significantly, from 1 to 1.2% to 1.4 to 1.6% (the best indicator for foreign laboratories is 0.5 to 0.7%). This indicator is calculated by dividing the total contribution of each laboratory by the number of its atomic clocks that participated in the formation of TAI and UTC in the period under review. The average contribution more correctly characterizes the quality of the frequency standards of each time laboratory.

    Additionally, an important indicator is the percentage of atomic laboratory clocks having the maximum allowable BIPM weight for an individual frequency standard. For 2022-2024, the figure ranged from 80% to 100%. The maximum possible weight depends on the total number of frequency standards involved in the formation of UTC in a particular billing period. This indicator was calculated as the number of atomic clocks having the maximum permissible weight divided by the total number of hours of this laboratory in each calculation period. All HSs from the SSFT have the highest rates of frequency instability and for most of the period under review make the maximum possible contribution to the formation of TAI and UTC.

    Figure 2: Comparative estimates of national time scale shifts. (All figures provided by the authors)
    Figure 2: Comparative estimates of national time scale shifts. (All figures provided by the authors)

    The characteristics of the Russian HS directly impact the formation of the national atomic and coordinated time scales of the Russian Federation TA(SU) and UTC(SU). Figure 2 shows the differences between national time scales and UTC.

    Coordinated Universal Time(k) relative to UTC in 2022-2024.

    The analysis of this data allows us to conclude that the UTC(SU) national coordinated time scale is one of the best national implementations of UTC, and the national atomic time scale TA(SU) occupies a leading position in terms of instability among the scales implemented in the leading national time laboratories.

    GLONASS’ time scale is linked to the readings of the SSTF, taking into account the correction of the Moscow decree time and are implemented by the GLONASS synchronization system, which is also based on hydrogen frequency standards. Figure 3 shows the discrepancy between the values of the GLONASS system time relative to the UTC(SU) time, which is currently less than 10 ns.

    Figure 3: Error in transmitting the national time scale of the Russian Federation UTC(SU) using GLONASS. (All figures provided by the authors)
    Figure 3: Error in transmitting the national time scale of the Russian Federation UTC(SU) using GLONASS. (All figures provided by the authors)

    UTC(SU) parameters are transmitted via GLONASS spacecraft and the first of the fourth-generation spacecraft, which has a passive hydrogen maser (PHM) on board, was launched into operational orbit on Aug. 7, 2023. In the spring of this year, flight tests of this device began, which showed an improvement in the accuracy of time transmission during the transition from the cesium to the hydrogen standard.

    Figure 4: The discrepancy between the spacecraft time scale and the UTC scale: 1 - Glonass-K2, orbit slot 26, 2 - Glonass-M, orbit slot 12. (All figures provided by the authors)
    Figure 4: The discrepancy between the spacecraft time scale and the UTC scale: 1 – Glonass-K2, orbit slot 26, 2 – Glonass-M, orbit slot 12. (All figures provided by the authors)

    Figure 4 shows the magnitude of the discrepancy between the time scales of the two GLONASS spacecraft. The cesium frequency standard installed on board the Glonass-M shows some of the best characteristics in the entire 20-year history of these spacecraft and demonstrates a daily relative frequency instability of 2×10-14, which is five times better than the design characteristics. Preliminary results of the use of the PHM as a source of reference vibrations and time synchronization pulses on board the Glonass-K2 in the same time interval shows a decrease of more than two times in the fluctuation error of forecasting the time scale with a relative daily instability of 7 × 10-15.

    Similar characteristics emerge when using the most conservative spacecraft control scenario. Here, the update of the on-board clocks parameters (OCP) of the on-board time scale departure model relative to the system is carried out once per turn, i.e. once every 11 hours and 45 minutes. This ensures a decrease in the value of the OCP contribution to the error of navigation definitions due to the space complex before updating them from 1.4 m with a daily instability of 1×10-13 to 0.1 m for a relative daily instability of 7×10-15. The results obtained make it possible to redefine the basic onboard standard and switch to the priority use of the HPM signal for the formation of reference oscillations and clock synchronization of GLONASS spacecraft signals.

    Figure 5  Passive hydrogen maser VC-1017.  (All figures provided by the authors)
    Figure 5 Passive hydrogen maser VC-1017. (All figures provided by the authors)

    Further development of this technology provides for installing a VC-1017 small frequency standard on board (Figure 5). Compared with the one presented in a previous article, this standard is more than two times lighter while maintaining the stability characteristics of the formation of reference vibrations (Figure 6).

    Figure 6  Measured instability of the VCH-1017 frequency relative to the state primary standard of time units, frequency and Russia’s national time scale for 40 days. The frequency drift was 1.51×10-15. The daily instability with the exception of drift is 1.42×1. (All figures provided by the authors)
    Figure 6 Measured instability of the VCH-1017 frequency relative to the state primary standard of time units, frequency and Russia’s national time scale for 40 days. The frequency drift was 1.51×10-15. The daily instability with the exception of drift is 1.42×1. (All figures provided by the authors)

    The launch of the Glonass-K2 spacecraft with the prototype of this HPM is planned for the first half of 2025. Its precision characteristics allow us to expect a further increase in the stability of time transmission by GLONASS.

    A significant improvement in the metrological characteristics of hydrogen frequency standards is achieved using a new system for forming a beam of atoms in a single energy state, which was developed before their industrial use. Thus, the daily frequency instability in active hydrogen frequency standards using a new beam formation system reached the level of (6-8) ×10-17.

    Figure 7: Microwave resonators for passive hydrogen frequency standards. (All figures provided by the authors)
    Figure 7: Microwave resonators for passive hydrogen frequency standards. (All figures provided by the authors)

    The basis for creating passive frequency standards of various sizes was the pioneering invention of an oscillatory structure, which is used in all passive hydrogen frequency standards for global navigation satellite systems. This microwave resonator made it possible to change the dimensions at a constant resonant frequency of 1,420,405,751 Hz, close to the frequency of the atomic transition. At the same time, the design proved to be suitable for harsh operating conditions, including requirements for the launch of the spacecraft. (Figures 7 and 8).

    Figure 8: Microwave resonators of different sizes for passive hydrogen frequency standards. (All figures provided by the authors)
    Figure 8: Microwave resonators of different sizes for passive hydrogen frequency standards. (All figures provided by the authors)

    Reducing the size of the “heart” of the frequency standard allows you to reduce the weight of all other structural elements — thermostats, magnetic screens, vacuum caps, supports, etc. At the same time, it is easier to achieve structural rigidity requirements and reduce the influence of destabilizing factors.
    The most important factor influencing the metrological characteristics of passive hydrogen frequency standards is the automatic frequency tuning system of the quartz oscillator to the frequency of the spectral line.

    Careful engineering of the auto-tuning system avoids the influence of control circuits on each other. In addition, a technical solution has been introduced in the new frequency standards of the GLONASS system, which makes it possible to reduce the impact of various factors on the stability of the output frequency.

    The results obtained allow us to consider the coming year 2025 as an important milestone in the development of time transmission technologies through the GLONASS system.

  • Seen & Heard: GM sued over data collection; archaeologists uncover hidden empire and more

    Seen & Heard: GM sued over data collection; archaeologists uncover hidden empire and more

    “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.


    Texas Sues GM for Allegedly Selling Drivers’ Data

    Photo: baona / iStock / Getty Images Plus / Getty Images
    Photo: baona / iStock / Getty Images Plus / Getty Images

    The Texas Attorney General’s Office has filed a lawsuit against General Motors (GM), alleging that the company unlawfully collected and sold driving data from more than 1.5 million Texas drivers. The lawsuit claims that GM gathered detailed information from vehicles manufactured since 2015. Additionally, the lawsuit alleges that GM deceived customers by compelling them to enroll in data collection services during the vehicle “onboarding” process, without fully disclosing how their information would be used. The collected data was reportedly used by third-party companies to generate “driving scores” which were then sold to insurance providers.

    3D Scans Reveal Medieval Secrets

    Photo: Stichting Grote Kerk Naarden
    Photo: Stichting Grote Kerk Naarden

    The Grote Kerk in Naarden, Netherlands, known as the “Sistine Chapel of the North,” is undergoing a 3D scanning project to uncover the secrets of its medieval ceiling murals. A team of researchers from various Dutch universities are collaborating to create a detailed digital 3D model of the church’s barrel vault, covering 700 square meters of painted planks and beams. The project aims to shed light on long-standing mysteries surrounding the artwork’s origins, including the identities of the artists and the precise timeframe of their creation. Researchers will use advanced 3D scanning technology to produce high-resolution digital replicas of the murals, allowing researchers to examine the artwork in extraordinary detail.

    Archaeologists Unearth Hidden Empire

    Photo: University of Cádiz
    Photo: University of Cádiz

    Archaeologists from the University of Cádiz in Spain have discovered 57 Roman Empire-era sites in the Sierra de Cádiz regions, revealed what researchers believe to be an undiscovered part of the Roman empire. The team used multispectral cameras and lidar to detect these hidden sites. The team has begun on-site excavations, including work at the Roman villa of El Canuelo in Bornos, and plans to continue its research to gain a more comprehensive view of Roman settlement in the region.

    Mapping Secrets of the Seafloor

    Photo: SuBastian/Schmidt Ocean Institute via CNN
    Photo: SuBastian/Schmidt Ocean Institute via CNN

    Oceanographers from the Schmidt Ocean Institute used advanced sonar technology to map a massive underwater mountain in Nazca Ridge, 900 miles off the coast of Chile. The team employed a hull-mounted sonar system on their research vessel, R/V Falkor, to create detailed maps of the seafloor. In addition to sonar mapping, the team used an underwater robot to explore the mountain and surrounding areas. This robotic technology allowed them to document rare marine life, including the ghostly white Casper octopus and unusual siphonophores nicknamed “flying spaghetti monsters”.

  • Launchpad: Anti-jamming, underwater topographic surveying, Triple-Band RTK receivers and more

    Launchpad: Anti-jamming, underwater topographic surveying, Triple-Band RTK receivers and more

    A roundup of recent products in the GNSS and inertial positioning industry from the November 2024 issue of GPS World magazine.


    OEM

    High-Dynamics MEMS Gyro
    Designed for precision navigation applications

    The GYPRO4300 is a high-dynamics MEMS gyro designed for precision navigation applications. It features a ±300 °/s input range, 200 Hz bandwidth and 1 ms latency, making it ideal for dynamic environments. With a bias instability of 0.4 °/h and an angular random walk of 0.07 °/√h, the GYPRO4300 offers high-performance sensing in a compact, digital and low size, weight and power (SWaP) package.

    Building on the GYPRO4300, the GYPRO4050 is a specialized north-seeking gyro for low-dynamics applications. This derivative offers 2° azimuth accuracy and is currently in the customer sampling stage. The GYPRO4050 maintains the same miniature package design as its predecessor, ensuring consistency across the product line.

    At INTERGEO 2024, TDK showcased a prototype based on an ongoing research and development project. This new development utilizes the same miniature package as the GYPRO4300 and GYPRO4050 but demonstrates ultra-low noise capabilities, achieving an azimuth accuracy of less than 1°. This product is slated for launch in 2025.

    Tronics Microsystems, tronics.tdk.com

    Anti-Jamming
    For challenging GNSS environments

    This series of anti-jamming antennas comes in two models, PT023 and PT024. The antennas are specifically engineered to operate in challenging environments characterized by complex electromagnetic interference, high-power signals and strong multipath effects.

    They are well-suited for scenarios involving low-elevation angle interference, high-power interference sources and radio communication system noise. The PT023 model utilizes multiple array elements combined with amplitude and phase manipulation to achieve spatial radiation shaping. This antenna also incorporates advanced multi-level filtering technology, effectively suppressing out-of-band noise power.

    The PT024 model features vertical and horizontal two-dimensional polarization suppressors. This design effectively mitigates the reception of both odd and even LHCP and RHCP signals originating from the rear of the antenna, according to the company. It can also suppress low-elevation multipath signals at the same frequency and out-of-band noise signals. These features seek to enhance the antenna’s performance in complex electromagnetic environments.

    Harxon Corporation, harxon.com

    Triple-Band RTK Receivers
    Integrated into ArduSimple’s evaluation boards

    The UM980, UM981 and UM982 RTK modules are integrated into the ArduSimple simpleRTK3B series to accelerate high-precision GNSS integration. Supporting Galileo High Accuracy Service (HAS) and fast update rate (50Hz), these devices are suitable for applications that require reliable and precise navigation.

    • SimpleRTK3B Budget (UM980): The most affordable step into triple-band precision.
    • SimpleRTK3B Fusion (UM981): Ideal for projects that need GNSS and inertial measurement unit (IMU) sensor fusion or tilt compensation.
    • SimpleRTK3B Compass (UM982): Designed for setups requiring dual antennas to determine the heading on moving platforms.

    ArduSimple has also integrated Unicore UM980, UM981 or UM982 modules into the simpleRTK3B Micro Unicore, part of its compact Micro-format lineup. It is designed for simple PCB integration, which can significantly speed up the development process and the time to market for new products.

    Unicore, en.unicore.com

    OEM GNSS Antenna
    Full-band, full-frequency antennas

    The HX-SE402A and HX-SE403A are full-band, full-frequency antennas that integrate GNSS capabilities with a low-profile radio antenna to support 858-878MHz and 902-928MHz frequency bands. This addresses the growing need for devices requiring both navigation and communication functionalities. Harxon’s new low-profile technology achieves the same functionality at 10 mm height, allowing greater versatility in applications that demand precise positioning alongside wireless communication. Additionally, Harxon offers custom tuning services to optimize integration into OEM end-user modules for specific applications.

    Harxon Corporation, harxon.com


    UAV

    OEMs
    Engineered for autonomous applications

    Advanced Navigation has expanded its Certus product line by introducing the Certus Mini series. This development marks a significant advancement in compact and high-performance navigation technology for field robots, autonomous vehicles and UAVs.

    The Certus Mini series comes in three variants:

    • Certus Mini D: A dual-antenna inertial navigation system (INS).
    • Certus Mini N: A GNSS-aided INS.
    • Certus Mini A: An attitude and heading reference system (AHRS).

    These lightweight systems, weighing no more than 55 grams (1.9 oz), offer impressive performance and cost-efficiency for their size. The Certus Mini D utilizes dual-antenna GNSS for accurate heading, position and velocity measurements. It operates on L1/L5 multi-constellation GNSS and offers enhanced interference immunity and position accuracy, particularly in challenging urban environments. The Certus Mini series suits various applications, including surveying, agricultural robotics, open-pit mining and asset tracking.

    Advanced Navigation, advancednavigation.com

    Direct Georeferencing Solution
    Designed for UAV mapping

    The APX RTX portfolio is a new line of direct georeferencing solutions designed for UAV mapping sensors. This system enables high-accuracy mapping across diverse environments, ideal for OEMs and UAV payload integrators. At the core of the APX RTX portfolio is the Trimble CenterPoint RTX technology, which offers both real-time and post-mission direct georeferencing. This capability allows for centimeter-level accuracy without the need for base stations, making it compatible with various sensors, including cameras, lidar and hyperspectral mapping devices.

    Trimble, trimble.com

    Fixed-Wing UAV
    Integrates YellowScan Voyager lidar

    The DT46 lidar UAV is a fixed-wing system designed for long-distance inspections and the creation of precise digital twins. The DT46 model integrates the YellowScan Voyager lidar with a high-resolution RGB camera. Equipped with a laser scanner with a 100° field of view and an acquisition rate of up to 2400 kHz, the YellowScan Voyager offers optimal point density for demanding projects.

    With a flight range of up to 300 km, depending on whether vertical take-off and landing (VTOL) or catapult take-off is employed, the UAV is designed for long-distance operations and can be deployed in under 15 minutes without requiring specialized tools. This autonomous solution offers a seamless end-to-end solution for various industries requiring aerial surveying and inspection capabilities.

    DELAIR, delair.aero

    Surveying

    GNSS Receiver
    Featuring a multi-constellation antenna

    The Stonex S900 GNSS receiver features a high-accuracy, multi-constellation antenna, a powerful UHF transmitter and the GSM 4G modem for a fully integrated communications choice, combined with a light and modern design. It tracks signals from GPS, GLONASS, BeiDou, Galileo and QZSS satellites. On the S900, two smart hot-swappable batteries can be inserted simultaneously, ensuring a maximum of 12 hours of operation. The power level can be checked and seen on the controller or directly on an LED bar on the battery.

    Stonex, stonex.it

    USV
    For underwater topographic surveying

    The HydroBoat 1500 is a versatile unmanned surface vessel (USV) driven by four powerful thrusters and designed to carry out underwater topographic surveys of lakes, rivers, reservoirs and other bodies of water. With a payload capacity of 60 kg, it can be integrated with the SatLab HydroBeam M4 portable multibeam echosounder, as well as a variety of other payloads such as side scan sonars and ADCPs. The vessel is IP67-rated and includes a millimeter-wave radar and 360° omnidirectional camera for accurate obstacle detection and safe navigation. It is also equipped with a dual RF and 4G cellular communications system.

    SatLab, satlab.com

    Laser RTK
    With a laser range of up to 50 m

    The Jupiter Laser RTK integrates GNSS, auto-IMU (inertial measurement unit), laser and dual-camera systems into a single unit. It incorporates a precise green laser that remains visible even in bright daylight. This feature allows for precise measurements of points in hard-to-reach, signal-blocked or potentially hazardous locations. It also features a night vision camera, allowing users to see feature points even in low-light conditions.

    The RTK system’s laser range is up to 50 m, making it suitable for challenging surveying environments. It incorporates visual technology to offer surveyors an immersive experience during surveying and stakeout operations, improving working efficiency and productivity.

    Comnav Technology, comnavtech.com

    UAV Lidar Scanner
    Designed for aerial surveying

    EchoONE combines Teledyne’s lidar and camera technology with Inertial Labs’ remote sensing payload instrument (RESEPI). EchoONE is designed for industries requiring precise aerial surveying and mapping solutions, such as land surveying, electric utility vegetation management, asset modeling, as well as transportation and infrastructure projects. Users can create detailed 3D models for infrastructure and asset management, offering valuable insights for maintenance and planning. EchoONE also generates fully undecimated georeferenced point clouds in real time, which allows for in-field verification. This capability is complemented by rapid post-processing through RESEPI’s “one-click” PC-Master Pro solution.

    Teledyne Geospatial, teledyneimaging.com

    Receiver
    With IMU tilt compensation

    The i83 Pro is an inertial measurement unit (IMU) real-time kinematic (RTK) GNSS receiver. This receiver combines GNSS capabilities with extensive compatibility options to address the diverse needs of surveying, construction, and mapping professionals. It incorporates CHCNAV’s third-generation GNSS antenna and the latest iStar algorithm, designed to boost GNSS signal tracking efficiency by 30%, according to the company. With 336 channels supporting GPS, GLONASS, BeiDou, Galileo and QZSS constellations, it can achieve centimeter-level precision rapidly, even in challenging environments.

    The i83 Pro supports various GNSS surveying modes, such as RTK Networks NTRIP and UHF base-rover configurations. It features an IP68-rated enclosure for dust and water protection, a compact and lightweight design for enhanced portability, a high-resolution color display for clear status information and a 20-hour battery life for continuous operation in rover mode.

    CHC Navigation, chcnav.com


    Mapping

    Software Solution
    Featuring a GIS interface

    LP360 Land is designed to process lidar, GNSS and SLAM data from handheld sensors, particularly the TrueView GO handheld scanner. It features a GIS interface that allows users to combine various geospatial datasets and offers SLAM point cloud processing capabilities. Additionally, LP360 Land includes advanced visualization tools that support multiple synchronized windows for 2D, 3D, profile and immersive views.

    Its coordinate system management includes datum and projection transformations. The software also offers quality assurance and control (QA/QC) tools, along with data editing and cleaning functionalities. Users can perform manual and automatic registration of point clouds and utilize an image explorer for contextual analysis by linking point clouds to photos, which allows for the generation of accurate and colorized point clouds even in GPS-denied environments.

    GeoCue, geocue.com

  • Celebrating Richard Langley as he contributes final column to GPS World

    Celebrating Richard Langley as he contributes final column to GPS World

    The November 2024 issue of GPS World features Professor Richard Langley’s 300th and final “Innovation” column. His first one appeared in the January/February 1990 issue, the magazine’s very first. In celebration of Richard’s decades-long contribution to GPS / GNSS / PNT, we are publishing a selection of testimonials and photos (below) from some of his colleagues and friends, gathered by his former students Sunil Bisnath and Attila Komjathy.


    Recollection from 1990, Trinidad – University of the West Indies

    It was 1990, late into a — thankfully warm — night in Trinidad. I still remember that moment vividly — the sense of anticipation mixed with skepticism. A small group of us, undergraduates from the Land Surveying Department at the University of the West Indies, were standing outside in the middle of the night. We were waiting, eyes fixed on the sky, holding our breath for signals that were promised to come — signals that the foreign professor, Richard Langley, assured us would soon appear and change our lives forever. Back then, GPS satellites were in scarce supply. Only a few were up there, and getting a signal was not guaranteed. Richard’s confidence, however, was unwavering. He was convinced that this technology — this new way of understanding our position in the world — would revolutionize everything we knew about land surveying and navigation. That year was my last in Trinidad. I left with memories of those nights under the stars, waiting for those elusive signals that did eventually come. Over time, I’ve met Richard at numerous Institute of Navigation events, and like the GNSS constellations, we have continued to grow and evolve yet remain united by our passion for a technology that continues to grow beyond our wildest expectations. – Professor Allison Kealy, FRIN, GAICD Director, Innovative Planet Research Institute Professor, Civil Engineering Swinburne University of Technology


    I was introduced to Richard more than 15 years ago. I learned quickly that he is not only a man of renown earned by his overarching knowledge on almost all aspects of satellite navigation, but also a man of action. Not surprisingly and probably well known, he was one of the first researchers investigating and improving the Precise Point Positing (PPP) technique. It is less well known that he was also an early adopter of the PPPPP concept. When asked what the abbreviation stands for, Richard would answer with a twinkle in his eye: “Proper preparation prevents poor performance!” I had the honor of seeing Richard in action during a joint measurement campaign where we applied both concepts. We wanted to collect observations of the new Galileo test satellites GIOVE-A and -B to use them for precise positioning. It happened that they had favorable visibility during the ION GNSS conference in Savannah, Georgia, in September 2009. So, we mounted a bunch of equipment onto Richard’s rental car and off we went through the streets, after carefully making sure that the GIOVE satellite were actually visibile and reference product generation back home in Munich, Germany, and New Brunswick, Canada, was properly working. Richard was steering the automobile in rapid turns on the parking lot to get some serious phase wind-up effect going. I was so concentrated on the data logging that I did not even feel the urge to throw up. The measurement collection went well and the data ended up being used for a joint publication the following year, potentially one of the first papers jointly using GPS and GIOVE. PPP using the PPPPP rule — there you go! – André Hauschild, Ph.D., Researcher German Aerospace Center (DLR)


    I first knew of Richard Langley through his Innovation column in GPS World. It was largely through this column that I acquired my basic knowledge of GPS. The columns were always so clear and so well written. It was a time of rapid change — the Internet, rapid data transfer between sites, and many, many other challenges. I received a grant to fund the Westford Water Vapor Campaign, and along with Arthur Niell of Haystack Observatory, we set out borrowing as many receivers, radiometers, and radiosondes as we could. Thus began my first “international” phone call to Richard Langley (the University of New Brunswick is, of course, in a foreign country) asking him to borrow receivers. Richard, perhaps because he did his postdoc here at MIT, and spent many hours out at Haystack, was more than amenable. He not only lent us three receivers but also a foreign visitor, Pieter Toor from Delft, and Virgilio Mendes, one of his graduate students. From them I learned immeasurably about the troposphere and water vapor distribution. The Westford Water Vapor Experiment was an important series of measurements, that helped us realize the potential of GPS before it was fully recognized by the community. Later, I was invited to join Jack Klobuchar and the Canadian equivalent of the FAA to fly to the University of New Brunswick, where I met Attila Komjathy for the first time. Later I also came to know Sunil Bisnath. Richard Langley trained a remarkable set of students, many (if not most) of whom have gone on to stellar careers. – Anthea J. Coster, Ph.D., Assistant Director; Principal Research Scientist MIT Haystack Observatory


    Professor Richard Langley is truly one of the masters of the GNSS community. He has been the mainstay of knowledge, scholarly activity, and mentoring to scholars and students for decades. His friendly demeanor and wiliness to help out wherever he can, makes him a pleasure to talk to and collaborate with. I look forward to seeing Richard at ION technical conferences with that big smile on his face and observing his love for and devotion to the art and science of navigation. – Professor Chris G. Bartone, Ohio University


    Richard and I are of the same “vintage” (date/time: referring to the period when we ramped up our work and study activity) and “terroir” (space/environment: referring to discipline background, circumstances and opportunities). We were both educated as surveyors, we both became academics, and we both mastered the arcane applied science field of geodesy. Geodesy in the 1970-1980s was undergoing a revolution driven by advances of the Space Age, reflected in the increasing use of Earth-orbiting satellites for precise positioning, mapping, gravity field determination, sea surface mapping, and much more. Richard and I are of the generation of geodesists in the 1980s that recognized — before any other engineering or science discipline — that GPS was going to change our world in profound ways. We pioneered its use for geodetic surveying (at the sub-cm accuracy level) even before GPS was declared “fully operational” in the mid-1990s. We had more than a decade head-start in understanding the principles of differential GPS, of carrier phase-based static positioning, and of the system itself. It is a head-start that continues to this day. We developed the first university GPS courses, wrote the first textbooks, educated the first generation of GPS scientists, developed the first measurement processing software, and helped revolutionize the practice of navigation. Although GNSS is considered the most important geoscientific technology that we use today, precise GNSS-enabled positioning has impacted so many other professional, scientific and social applications. With the founding of GPS World’s “Innovation” column, Richard launched an amazing educational and industry outreach service. Those articles tracked the advances in GPS/GNSS technology and applications. While there are still some of our geodesy generation making contributions to their discipline, Richard has continued to promote GNSS for 35 years in a unique way, through his careful curation of “Innovation” column articles. They remain a joy to read. Richard, keep up this great service to the positioning, navigation and timing (PNT) community. – Professor Chris Rizos, President International Union of Geodesy & Geophysics (IUGG) School of Civil & Environmental Engineering UNSW Sydney Australia


    I have had the pleasure of knowing Richard since the mid 1980s, when we were part of the team that produced the first and highly successful book on GPS, namely the Guide to GPS Positioning. We have interacted regularly ever since. I have always appreciated reading Richard’s papers for their clarity, thoroughness and novel content. His Innovation column in GPS World for 35 years is now a GPS classic that post-graduate students and experts alike learn from and enjoy reading. Richard has deservedly received major awards for his numerous and outstanding work. Richard, I hope that we will continue to benefit from your contributions for years to come. – Professor Gérard Lachapelle, University of Calgary


    Despite being a highly respected leader in the field of PNT, Richard remains a humble human being. He sets a high standard for his work and is generous with his time to catch even the smallest errors in research papers. It has been a great pleasure to get to know him and to have the opportunity to work with and learn from him. He is an inspiration and a role model for me. – Professor Jade Morton, Ph.D., Helen and Hubert Croft Professor Ann and H.J. Smead Aerospace Engineering Sciences Department University of Colorado Boulder


    I have had the privilege of knowing Prof. Richard Langley for my entire career in PNT and have always been greatly impressed with his wealth of knowledge and research on high-precision applications of GPS. I first met him in the late 1980s at meetings of the Civil GPS Service Interface Committee (CGSIC) and the early Institute of Navigation conferences on GPS in Colorado Springs. When I joined the navigation team at the U.S. Department of Transportation as a young engineer in 1988, we all had copies of The Guide to GPS Positioning, that Prof. Langley co-authored with David Wells and that we greatly utilized! Since that time, I have enjoyed interfacing with Prof. Langley at ION conferences and serving with him on the ION Council. I have learned so much from his research, including his development of the UNB-RTK system and the study of atmospheric effects for the FAA Wide Area Augmentation System (WAAS), as well as the very informative articles he has published in GPS World! – Karen Van Dyke, Director, Positioning, Navigation, and Timing U.S. Department of Transportation


    The 35-year anniversary of Richard’s Innovation column in GPS World seems amazing, also recalling the recent 30-years celebration of the International GNSS Service (IGS), which to many of us seemed like an eternity. This is not surprising, however: from the Guide to GPS Positioning, co-authored by Richard (my first GPS handbook when I started learning about GPS in November 1989 at ICC, Barcelona); to the knowledge, motivation and empathy we have always enjoyed when meeting Richard in so many different workshops (ION, Beacon Satellite…) and collaborative works (e.g., IERS Conventions…). For him, this is normal. CONGRATULATIONS. – Professor Manuel Hernandez-Pajares, UPC-IonSAT, IEEC-CTE Head of the UPC-IonSAT Research Group, IGS Associate Analysis Center Department of Mathematics, Universitat Politècnica de Catalunya, Barcelona, Spain


    Professor Langley has been a vital contributor to the Institute of Navigation (ION) for four decades, serving in various volunteer and leadership capacities. In his most recent role, Richard has served as the Editor-in-Chief of NAVIGATION, The Journal of the Institute of Navigation, our esteemed peer-reviewed technical publication. Since taking on this role in 2020, he has expertly led a team of associate editors, guiding NAVIGATION through a transformative period as it transitioned from a traditional print publication to a fully open-access journal. Under his leadership, the journal has seen a remarkable increase in its impact factor, most recently rising to 3.1. Beyond his editorial work, his most important contribution lies in his mentorship. He has profoundly influenced the next generation of GNSS experts, nurturing countless graduate students through ION’s programs and initiatives while fostering their professional development. His dedication to education and commitment to innovation has enriched our community. We deeply value our ongoing collaboration with Richard. His unwavering commitment, expertise, and passion for GNSS and ION have made him an integral part of our organization. It is a privilege to work alongside such a dedicated professional. – Lisa Beaty, Executive Director Institute of Navigation


    Like many others, I look back to a long friendship with Richard, who’s always been a mentor and model for me. His sharp mind, paired with a distinct sense of very British humor makes each meeting with him a source of inspiration and memorable experience. From gentle spelling and grammar corrections in manuscripts to advice and leadership in GNSS-related projects, he always offers a helping hand, contributes in-depth knowledge and one or another personal anecdote. From him, I learned the “six P” rule: proper planning and preparation prevents poor performance. This unforgettable saying not only reflects the rigor Richard applies to his work, it also provided me a guideline that I’m now passing on to my own students. – Oliver Montenbruck, Ph.D. Head, GNSS Technology and Navigation Group German Aerospace Center (DLR)


    I would like to say, as someone who is not his direct advisee, I’ve always appreciated his avuncular spirit, mentorship, and encouraging guidance over the years. I join you in toasting to him and his successes in growing and connecting the navigation community over his many years of service, in addition to all his technical achievements and innovations. Cheers to Richard! – Professor Seebany Datta-Barua Illinois Institute of Technology


    Richard has been a highly respected leader in the GNSS community for more than 30 years, making his mark as a creative innovator, a mentor for generations of future leaders and contributors to the advancement of GNSS, and as an insightful and patient teacher. The well-worn copy of his Guide to GPS Positioning on my bookshelf has helped me and countless students quickly pick up the basics, while his cheerfully engaging series of “Innovation” columns in GPS World explored every feature, misconception, novel application, mystery, and intricacy of GNSS. And, he literally put Fredericton on the map for the GNSS community. – Penina Axelrad, Distinguished Professor University of Colorado


    When I became GPS World’s managing editor, in 2000, my exposure to GPS was limited to a few journal articles I had read as a graduate student in international security at MIT in the mid-1990s. Much of my education on the subject during the steep learning curve that followed came from Richard’s “Innovation” column. Also, as his liaison to the magazine, I was responsible for entering his many, meticulous edits to each column, which, at the time, he sent me by fax. Nearly a quarter century later, Innovation is still my favorite section in the magazine. I will miss it greatly.” – Matteo Luccio, Editor-in-Chief, GPS World


    Good memories of my collaborations with Richard span a long time to almost the operational beginnings of GPS. Examples range from our collaboration on the Handbook for GNSS to our shared lecturing at the “GPS for Geodesy” school, in Delft, 1996. I always experienced with admiration Richard’s encyclopedic knowledge and excellent lecturing and writing skills. The only one thing that I would have wished for is that Richard would have turned his excellent Innovation columns in GPS World into a book. That would have been a bestseller for sure. – Professor Peter Teunissen Delft University of Technology


    I first met Richard in 1982 while a postdoc at MIT about the time that he joined the faculty at the University of New Brunswick, after his postdoc in the same MIT department. After research in VLBI and SLR, he was one of the early pioneers in the development of GPS for precise positioning applications, with contributions in several areas, such as signal multipath and tropospheric refraction. We both taught at the International School of GPS for Geodesy in Delft, first in 1995, and contributed to the resulting monograph, GPS for Geodesy. I have a vivid memory of drinking beer with him in a bar in Delft after a long day at the school. – Professor Yehuda Bock Scripps Institute of Oceanography


    I first met Richard shortly after joining MIT as a Ph.D. student in 1979. He was a postdoctoral fellow for two years with MIT’s Department of Earth and Planetary Sciences, carrying out research in geodetic applications of lunar laser ranging and very long baseline interferometry after completing his Ph.D. at York University, Toronto. His research at MIT led to the discovery of a 50-day oscillation in atmospheric angular momentum and length of day determined from lunar laser ranging data. This work was published in 1981 in Nature. Richard has been publishing impactful papers on important topics since very early in his career. His contributions to GPS World’s “Innovation” column have followed that trend. – Professor Thomas Herring Massachusetts Institute of Technology


    I did not have tons of personal contact with Richard, but the contact I did have showed me that he was a man of very high standards, and it’s clear that his dedication to the field is enormous. The combination of high standards and selfless dedication is what moves us forward. He also attracted and produced a cadre of highly talented and successful researchers that continue to have an enormous impact on the field. These are great things! – Anthony J. Mannucci, Ph.D. Deputy Manager, Tracking System and Applications Section Jet Propulsion Laboratory


    Years ago when assembling material for my advanced GNSS signal processing course here at the University of Texas, I found that for several topics Richard’s “Innovation” column had just the discussion and analysis I was looking for my students to learn. His writing is unfailingly engaging and lucid! What a gift to the community his “Innovation” column has been! Richard is an amateur radio enthusiast. Many of the insights on radio in his columns are backed up by his practical experience with long-distance ham radio communications. He’s connected with people from continents away from his home base in New Brunswick. – Professor Todd E. Humphreys, Ashley H. Priddy Centennial Professorship in Engineering Dept. of Aerospace Engineering and Engineering Mechanics The University of Texas at Austin


    I first met Richard Langley in 1989 at what was my first ION Satellite Division meeting. It was a young-looking crowd, but we both could pass for young men then. I also met another young man by the name of Glen Gibbons who was circulating among the attendees to gauge interest in a trade magazine devoted to GPS that he was thinking of launching. GPS World played an important role in my career as a GPS engineer, particularly for its “Innovation” column, edited by Richard. His early columns (such as “Why is the GPS Signal So Complex?”) are classics of cogent writing and served as an inspiration to me when I tried my hand at writing about GPS. His skills as an editor, and his generosity to help a friend avoid embarrassing himself, proved even more helpful to me. My debt to Richard has grown over the years, and so has my admiration and affection for him. – Professor Pratap Misra, Professor of the Practice of Mechanical Engineering Tufts University


    When I googled “Richard Langley,” just for fun, I got multiple returns — among them “professional football player,” “state politician,” “actor,” “model maker” and I thought for a while that those are Richard’s other personalities that I didn’t know about. Well, a slight refinement of my search “Richard Langley, geodesy” got me what I was looking for — pages and pages on the accomplishments of the Richard Langley as one of the first scientists who recognized the great potential of GPS as a scientific and civilian tool and an everyday commodity, research publications that all GPS “insider wannabees” have read and memorized, and articles documenting his commitment to GPS World, especially its “Innovation” column — which has long been one of my favorite reads. I congratulate Richard on the 35th anniversary of this outstanding column! – Professor Dorota Grejner-Brzezinska, Vice-Chancellor for Research at University of Wisconsin-Madison


    Richard and I first met when I spent a post-doc year at the University of New Brunswick in 1983/84. The nucleus of the Bernese GPS software emerged from this visit. Richard and I became friends and stayed in contact after this visit. We met last time in Bern at the 2024 IGS Symposium commemorating 30 years of the International GNSS Service. What I admire most about Richard is his scientific breath and his at times artistic use of the English language — he announced his visit to Bern with the words “I will be there if I don’t ‘keel over’ between now and then.” – Professor Gerhard Beutler University of Bern


  • Innovation Insights: It starts with the physics

    Innovation Insights: It starts with the physics

    Click to read the full Innovation article, “Innovation: A look back at 35 years of ‘Innovation’


    Innovation Insights with Richard Langley
    Innovation Insights with Richard Langley

    IT’S ALL PHYSICS. How things work, that is. Well, maybe a little chemistry too in some cases. I might be a little biased in my opinion given that I’m an applied physicist by training. Radio? Satellite navigation? Yes, the principles of their operation are all governed by physics. Many physicists of my generation started out as radio tinkerers. I’ve recounted in this column before that I built my first radio (from a kit) when I was 14 (not counting the crystal radio that my father helped me to put together when I was 8 or 9). I built a few more during high school, got into radio astronomy as an undergraduate and did a Ph.D. in the application of very long baseline (radio) interferometry to geodesy.

    The great American physicist Richard Feynman was also a radio tinkerer in his youth. He recounts in one of his autobiographical books how he used to fix radios. Since he would approach the task of repairing each non-functioning set by first contemplating why it wasn’t working, he got the reputation of fixing radios by thinking!

    One of Feynman’s special abilities was in explaining how things worked. In fact, he has been called “The Great Explainer.” He authored what is arguably the best physics textbooks ever produced: The Feynman Lectures on Physics. The three-volume set, developed from his Caltech lectures to undergraduates between 1961 and 1964, covers mechanics, radiation, electromagnetism, matter and quantum mechanics. Many students and practicing physicists have learned or relearned aspects of physics from the famous “red books.” Many more will now thank Caltech, which recently put the Lectures online for anyone to read.

    In the February 2016 column, we learned about the development of a microprocessor-controlled multi-element GNSS antenna array for interference rejection. While there are many textbooks that describe how multi-element antennas work, Feynman explains their operation in his Lectures from first principles–from the principles of physics. The phenomenon governing the behavior of antennas with multiple elements is called interference.

    If we combine two electromagnetic waves, they will interfere with each other with a result that depends on the relative phase (or phase difference) of the waves. The waves might reinforce each other leading to a larger net amplitude, called constructive interference, or partially or fully null each other out, called destructive interference. When we apply this concept to the signals transmitted by a pair of antennas making up an array in a horizontal plane, we find that the array has directionality. That is, if we space the antennas by one-half wavelength of the signal to be transmitted and feed the antennas in phase (zero phase difference), we will transmit a strong signal in the directions perpendicular to the baseline connecting the antennas (say east-west) and no signal in the orthogonal directions (north-south). If we use this antenna pair for receiving, we will have a null in the reception pattern to the north and to the south and will be insensitive to signals arriving from those directions. And as Feynman describes in his lectures, by adding more antennas to the array and “some cleverness in spacing and phasing our antennas,” we can have a fairly narrow pattern null in a chosen direction. In the case of a GNSS antenna array, that direction might be that of a jamming signal and so we can null out the jammer and maintain a positioning capability.

    There is more to it in developing a practical microprocessor-controlled GNSS antenna array, but it starts with the physics.

  • Highlights from INTERGEO 2024

    Highlights from INTERGEO 2024

    Photo: GPS World Staff
    Photo: GPS World Staff

    The GPS World team touched down in Stuttgart, Germany, for INTERGEO 2024, held from Sept. 24-26.

    This year’s expo and conference, which attracted more than 17,000 visitors from 121 countries and featured 579 exhibitors, showcased solutions to address critical global issues such as climate change, urbanization and GNSS jamming and spoofing.

    Ray Weatherbee, CEO, Stonex USA, and Tim Carolin, Account Executive, GPS World. Photo: GPS World Staff
    Ray Weatherbee, CEO, Stonex USA, and Tim Carolin, Account Executive, GPS World. Photo: GPS World Staff

    GPS World Publisher Brian Kanaba and Account Manager Tim Carolin made their debut at the show, joining veteran Editor-in-Chief Matteo Luccio. The team had the opportunity to explore the expansive show floor, experiencing firsthand the latest innovations from around the world. With three floors of exhibits, Kanaba, Carolin and Luccio engaged with partners and established valuable connections with industry leaders. Their attendance highlights GPS World’s dedication to remaining at the forefront of geospatial technology and trends, emphasizing a strong commitment to collaboration and innovation within the industry.

    GPS World staff: Matteo Luccio, Editor-in-Chief, Brian Kanaba, Publisher, and Tim Carolin, Account Executive. (Photo: GPS World Staff)
    GPS World staff: Matteo Luccio, Editor-in-Chief, Brian Kanaba, Publisher, and Tim Carolin, Account Executive. (Photo: GPS World Staff)
  • Innovation: A look back at 35 Years of ‘Innovation’

    Innovation: A look back at 35 Years of ‘Innovation’

    Innovation Insights with Richard Langley
    Innovation Insights with Richard Langley

    Click to read the full Innovation Insights column, Innovation Insights: It starts with the physics”

    This is my 300th and last “Innovation” column in GPS World. I have mixed feelings about stopping the column. I’ve really enjoyed doing it for the past 35 years, but editorial deadlines can be difficult to meet sometimes, especially when I’ve got other things to get done or if they come in the middle of a vacation.

    To rephrase the old adage, editorial deadlines wait for no one. Looking back, I don’t know how I managed to initially produce six and then 10 columns each year, along with all my other duties as a university professor. Mind you, as I’ll soon discuss, most of the articles in the columns were authored by others. My job mostly was to edit the articles to help the authors tell their stories in a particular GPS World style and sometimes to improve their submitted figures. Additionally, in 2006, I started to write a sidebar called “Insights” to provide some basic background material about each column’s topic. A few years ago, I became editor-in-chief of the Institute of Navigation’s journal NAVIGATION, which takes up a bit of my time, along with lecturing and managing a research team. So, at 75, I thought it might be a good time to lessen the load a little bit.

    In this last column, I’m going to tell the story of how “Innovation” came to be and review some of the column’s developments over the years.

    How it all began

    In the fall of 1989, GPS World’s founding editor, Glen Gibbons, approached Dave Wells, Ph.D., a fellow faculty member in the then Department of Surveying Engineering at the University of New Brunswick (UNB) – about assisting with a “technology/product development column” in the magazine he was about to start. Glen wanted it to provide “an analysis and commentary on the research, development, product issues and needs of the GPS community.” And, since GPS World readers would have marked differences in their knowledge and expertise in the GPS area, “the column should deal with issues that have broad application and interest and are presented in terms that are accessible to as wide a range of readers as possible,” Glen said in a letter to Dave.

    Glen had heard about Dave’s (and UNB’s) early involvement with GPS. When I came to UNB in 1981, UNB was already carrying out some of the first theoretical studies on how GPS could be used by surveyors and geodesists for precise positioning. Shortly afterwards, UNB participated in some of the first surveys using the Macrometer V-1000 and Texas Instruments TI 4100 receivers and developed software to process the resulting data. In 1983, Dr. Gerhard Beutler from the Astronomical Institute of the University of Bern came to UNB on a sabbatical and began developing his own GPS data processing software that would eventually become the Bernese GNSS Software or just “Bernese” to those in the know. Somehow, in between our GPS algorithm and software development, teaching, mentoring graduate students and other duties, we managed to self-publish the first textbook on GPS, Guide to GPS Positioning. With a publication date of December 31, 1986, it went on to sell more than 12,000 copies in the English version alone. It was also translated into Chinese, Spanish and Vietnamese. So, perhaps it is not surprising that Glen came to knock on UNB’s door when he was starting up his magazine.

    Getting back to Glen’s letter, he went on to say, “It would be possible to handle the preparation or presentation of the column in one of several ways: We could identify a single person who would have primary responsibility for writing all the columns and whose byline would appear on them; we could have a person act as the coordinating editor responsible for obtaining suitable contributions from various authors; or we could establish a collective or institutional editorship with column responsibilities shared among a pool of contributors.”

    The letter arrived in early November 1989, and Dave, I and Alfred Kleusberg, Ph.D., who was a research fellow in the department (and subsequently a professor), began to discuss whether we wanted to take on the responsibility for the column and, if so, how we would manage it. I shortly departed to the University of Bern, where I would spend the better part of two months during my first sabbatical. Communication had to take place using e-mail, although phone, telefax and telex were also possible. Universities had e-mail before most other organizations thanks to BITNET (known initially in Europe as the European Academic and Research Network or EARN), a computer network that predated the Internet. My BITNET e-mail address was lang@unb or [email protected]. As I recall, the personal part of the address was limited to at most four characters. So, when UNB joined the Internet, I basically kept the same e-mail address: [email protected]. I talked about GPS and the Internet in the November 1995 edition of the column. But I’m getting ahead of myself.

    FIGURE 1: First page of Dave Wells’ notes from December 31, 1989 on how UNB would manage the “Innovation” column. (Photo: GPS World archives)
    FIGURE 1: First page of Dave Wells’ notes from December 31, 1989 on how UNB would manage the “Innovation” column. (Photo: GPS World archives)

    That December, the three of us more or less agreed that we would handle the column in some form. From Switzerland, I sent Dave a list of 12 possible topics for the column, but I added the rider: “Note that I am not necessarily volunteering to write any of the articles.” As we know, things turned out a little differently. During the university’s Christmas break, after I returned to Fredericton, we met at Dave’s house to discuss how we would manage the column in more detail. We met on New Year’s Eve — a Sunday afternoon — and decided that Alfred Kleusberg and I would manage the column as co-editors, with Dave serving as one of the inaugural members of the magazine’s Editorial Advisory Board. The column editorship was to be a blend of the second and third of Glen’s suggestions. The task wasn’t supposed to be too onerous. After all, the magazine was to be published bimonthly. Lots of time to get someone to write an article and for Alfred and I to edit it. Or so we thought. And the column was to be called, simply, “Innovation.” I don’t recall who came up with the name — whether it was one of the three of us or Glen, but the notes from that Sunday afternoon meeting have “Innovation” written at the top of the first page (see FIGURE 1). Ideally, as per Glen’s suggested guidelines, column articles were to be tutorial in style or written in a way that they could be understood, for the most part, by non-experts in the field.

    At that Sunday afternoon meeting, we decided that Dave and Alfred would write the article for the first column. It was an introduction to GPS and some possible applications titled “GPS: A Multipurpose System.” With a couple of iterations of the article back and forth with Glen via fax (GPS World didn’t have e-mail until a few years later) and a figure delivery by FedEx, the column debuted in GPS World, Volume 1, Issue 1, January/February 1990.

    It used three different positioning scenarios to explain how GPS could provide positioning accuracies from a Selective Availability-constrained 100 meters down to the sub-centimeter level. It also outlined GPS’s ability to determine platform attitude with multiple antennas and its use for accurate time transfer.
    There was a brief introductory couple of paragraphs, which would be a column standard (later extended to a sidebar). That first introduction went as follows:

    “‘Innovation’ will be a regular column in GPS World and will comment on GPS technology, product development, and other issues and needs of the GPS community. Coordinating editors are Alfred Kleusberg, Ph.D. and Richard Langley, Ph.D. both of the Department of Surveying Engineering at the University of New Brunswick in Fredericton, New Brunswick, Canada, as is David Wells, Ph.D., co-author of this initial column.

    “The first few columns will introduce GPS World readers to GPS technology. This first column focuses on the many capabilities of GPS. The next column will look at the flip side — what are the limitations of GPS? ‘Innovation’ will discuss some intriguing questions in future columns: Why is the GPS signal so complicated? How have surveyors been able to use it to get such accurate results? How serious is selective availability? We will also devote columns to exploring in depth some of the issues raised in this column: GPS and electronic charts, GPS and geographical information systems and prospects for using GPS and GLONASS together. We welcome readers’ comments and topic suggestions for future columns.”

    That introduction listed the topics for the first year of “Innovation.” They were written by Alfred, me, both of us, or other researchers at UNB and, in one case, by colleagues at the Canadian Hydrographic Service. We had a very positive response to our first few column articles, so Glen kept us on, but at some point in 1990, he told us the magazine was going to 10 issues a year. There were just too many GPS-related developments to be covered in just six issues. So now there would be a monthly column except for the July/August and November/December issues.

    In the second year, Alfred and I continued to write some tutorial articles for the column, but we started to invite others to submit articles, which we would then edit for style and space, and that became the tradition. Over the years, we have had hundreds of leaders in GNSS technology development and applications pen articles. In the second and third years of the column, for example, we featured articles by Stephen DeLoach on precise real-time dredge positioning, Jack Klobuchar on ionospheric effects on GPS, Edward Krakiwsky on GPS vehicle location and navigation, Yehuda Bock on continuous monitoring of crustal deformation, Keith D. McDonald on GPS in civil aviation, David Coco on GPS as satellites of opportunity for ionospheric monitoring, Derrick Peyton on using GPS and remotely-operated vehicles to map the ocean, Oscar Colombo and Mary Peters on precision long-range DGPS for airborne surveys, Adam Freedman on measuring the Earth’s rotation and orientation with GPS, Christian Rocken and Thomas Kelecy on high-accuracy GPS marine positioning for scientific applications, Marvin May on measuring velocity using GPS, Thomas Yunck describing a new chapter in precise orbit determination, and Gregory Leger on using GPS-equipped drift buoys for search and rescue operations. And the list goes on and on.

    As I mentioned, in the second year of GPS World, there were 10 issues. That changed in 1993, when the magazine went to 12 issues a year, but the September and December issues were “Showcase” issues featuring more industrial news and announcements of new products. It was also to include “The Almanac” — an update on the GNSS constellations, which I also looked after. Eventually, the “Showcase” issues became regular issues but with “Innovation” replaced by “The Almanac” at the “back of the book.”

    Figure 2A Different eras of “Innovation” throughout the years; the January 1993 edition (left) and the January 2000 edition (right). (Photo: GPS World archives)
    Figure 2A Different eras of “Innovation” throughout the years; the January 1993 edition (left) and the January 2000 edition (right). (Photo: GPS World archives)

    The column look changed a few times over the years, typically coinciding with magazine makeovers, with the logo changing from the original 3D terrain graphic to a logo of people with stuff in their hands starting in January 1999, to a “bits” logo from January 2001, to a somewhat plain format from September 2003, with the “Insights” sidebar and my photo from April 2006, to a circle photo from November 2015, and with a new photo from January 2016. FIGURES 2A, 2B and 2C show representative column snapshots for each era.

    Figure 2B Different eras of “Innovation” throughout the years; the January 2003 edition (left) and the September 2003 edition (right). (Photo: GPS World archives)
    Figure 2B Different eras of “Innovation” throughout the years; the January 2003 edition (left) and the September 2003 edition (right). (Photo: GPS World archives)

     

    FIGURE 2c  Different eras of “Innovation” throughout the years; the April 2006 edition (left) and the February 2016 edition (right). (Photo: GPS World archives)
    FIGURE 2c Different eras of “Innovation” throughout the years; the April 2006 edition (left) and the February 2016 edition (right). (Photo: GPS World archives)

    The tutorials

    As I mentioned earlier, right from the beginning of “Innovation,” we decided to have essentially two types of articles in the column: discussions of recent advances in GPS (and later GNSS) applications and related technology written by guest authors and tutorials explaining the fundamentals of GNSS including how the three main components of GNSS work: the satellites, the control segment and the user equipment. Here is a list of some of the tutorials written by the UNB team (mostly me) that were featured in “Innovation”:

    • GPS: A Multipurpose System (January/February 1990)
    • The Limitations of GPS (March/April 1990)
    • Why is the GPS Signal So Complex? (May/June 1990)
    • The Issue of Selective Availability (Sept./Oct. 1990)
    • Comparing GPS and GLONASS (Nov./Dec. 1990)
    • The GPS Receiver: An Introduction (Jan. 1991)
    • The Orbits of GPS Satellites (March 1991)
    • The Mathematics of GPS (July/August 1991)
    • Time, Clocks, and GPS (Nov./Dec. 1991)
    • Basic Geodesy for GPS (February 1992)
    • The Federal Radionavigation Plan (March 1992)
    • Precise Differential Positioning and Surveying (July 1992)
    • The GPS Observables (April 1993)
    • Communication Links for GPS (May 1993)
    • GPS and the Measurement of gravity (Oct. 1993)
    • RTCM SC-104 DGPS Standards (May 1994)
    • NMEA 0183: A GPS Receiver Interface Standard (July 1995)
    • Mathematics of Attitude Determination with GPS (Sept. 1995)
    • A GPS Glossary (Oct. 1995)
    • GPS and the Internet (Nov. 1995)
    • The GPS User’s Bookshelf (Jan. 1996)
    • Coordinates and Datums and Maps! Oh My! (with Will Featherstone; Jan. 1997)
    • The GPS Error Budget (March 1997)
    • GPS Receiver System Noise (June 1997)
    • GLONASS: Review and Update (July 1997)
    • The UTM Grid System (Feb. 1998)
    • A Primer on GPS Antennas (July 1998)
    • RTK GPS (September 1998)
    • The GPS End-of-Week Rollover (Nov. 1998)
    • The Integrity of GPS (March 1999)
    • Dilution of Precision (May 1999)
    • GPS, the Ionosphere, and the Solar Maximum (July 2000)
    • Navigation 101: Basic Navigation with a GPS Receiver (October 2000)
    • Getting Your Bearings: The Magnetic Compass and GPS (Sept. 2003)
    • GPS by the Numbers: A Sideways Look at How the Global Positioning System Works (April 2010); this was the 200th “Innovation” column.

    As you can see, the tutorials became fewer as the years went by. As my research career expanded, I just didn’t have the additional time to write more tutorials. I had taken over sole responsibility for the column in 1997, shortly after Alfred Kleusberg left UNB to pursue a career opportunity in Germany.

    However, the tutorial columns were (and still are) popular judging by the comments sent to GPS World and the number of citations for some reported by Google Scholar. For example, the one on dilution of precision has been cited in papers, theses, and reports 837 times to date. While not as many as a paper on an important medical breakthrough, it’s not a bad record for an article on a navigation topic.

    Changes at the top

    The column has seen four changes of editorial leadership at GPS World. Glen Gibbons, the founding editor, stepped down as editor-in-chief in July 2005 and shortly afterward started up his own publishing company to produce the magazine Inside GNSS. Alan Cameron took over the job in 2006, and subsequently became the magazine’s publisher and editor-at-large. Tracy Cozzens became the senior editor in 2019 with responsibility for “Innovation,” and then Matteo Luccio became editor-in-chief of the magazine in May 2021. I’m happy to say I got along well with all of these “bosses,” and they continued to put up with me even when I got the column in at the last moment. Additionally, the magazine’s various art directors over the years have always made the column look good.

    However, after I took over sole responsibility for the column, there were no changes at the bottom. So, I’ve ended up being the longest serving GNSS rapporteur or editor, with Glen and Alan and Tracy having retired at different epochs during the past decade. In addition to the column, I have contributed a number of shorter articles to the magazine and the GPS World website over the years, sometimes joined by colleagues from different organizations, in particular the German Aerospace Center.

    A bit of my own history

    I wasn’t going to bother with an “Insights” sidebar for this last column. The column isn’t about a single topic that needs any background information. But you might be wondering how I got this gig as the “Innovation” editor (apart from what I’ve already told you) or got my job at UNB for that matter. So, I’m repurposing the “Insights” sidebar from the February 2016 issue of GPS World, in which I talk a bit about antenna arrays and my own radio tinkering. It doesn’t mention that after getting my Ph.D., I spent two years at MIT as a postdoctoral fellow working under the famous physicist Irwin Shapiro on analyzing lunar laser ranging data to uncover subtle changes in Earth’s rotation due to the fluctuating winds of its atmosphere. Even as a graduate student, I was involved with satellite navigation and helped to uncover a bias in the coordinate system used by the U.S. Navy Navigation Satellite System, commonly known as Transit, by comparing station coordinates with those I obtained in my very long baseline interferometry research. I’ve always been a radio nerd both in my day job and as an avid shortwave radio hobbyist. So, it is not too surprising that I got involved with GPS and then GNSS (including ionospheric studies) and established a GNSS research group at UNB with some stellar graduates over the years.

    The archives

    I would like to report that all 300 “Innovation” columns are available for download on the Internet. Unfortunately, that is not the case — yet. Perhaps that’s something that could be done when I actually do retire. However, the first two years of the column are available here: gauss.gge.unb.ca/gpsworld/innovation.html. Hopefully, we can continue to keep that URL alive for a few years. If it should disappear, just Google it or consult the “Wayback Machine” at archive.org. The columns since June 2008 (with a few more before that) are available here. Full digital versions of each issue of the magazine since January 2009, including the “Innovation” column, are available here.

    The end

    And there you have it. It only remains for me to thank all of the authors who have shared their research and understanding of the many facets of GNSS in the column over the past three-and-a-half decades, the staff at GPS World for getting the column into the print and later the electronic editions on the Web, the readers whose positive feedback encouraged me to keep the column going, and to my wife, Marg, who let me spend the long hours on the column when I should have been attending to things around the house. So, now, to paraphrase a much better journalist than I: Goodbye, and good luck.


    The November 2024 issue of GPS World features Professor Richard Langley’s 300th and final “Innovation” column. His first one appeared in the January/February 1990 issue, the magazine’s very first. In celebration of Richard’s decades-long contribution to GPS / GNSS / PNT, we are publishing a selection of testimonials and photos from some of his colleagues and friends, gathered by his former students Sunil Bisnath and Attila Komjathy. Click here to read the testimonials.

  • BeiDou Navigation Satellite System in 2024

    BeiDou Navigation Satellite System in 2024

    Successful launch of the 59th and 60th BDS satellites on Sept. 19, 2024. (Photo: International Cooperation Center of China Satellite Navigation Office)
    Successful launch of the 59th and 60th BDS satellites on Sept. 19, 2024. (Photo: International Cooperation Center of China Satellite Navigation Office)

    Upholding the principles of “superior construction, excellent management, and substantial development,” the BeiDou Navigation Satellite System (BDS) implements multifaceted strategies to ensure uninterrupted and stable system operations and services, with its backup satellites launched into orbit as per the scheduled plan in 2024. Concurrently, research on next-generation BDS technology upgrades and related technological trials for integration with low-Earth orbit (LEO) positioning, navigation and timing (PNT) systems are vigorously promoted, further enhancing international collaboration and propelling the continuous advancement of BDS in the new era.

    1. System operation and services

    All figures provided by the author.
    All figures provided by the author.

    BDS currently consists of 45 operational satellites in orbit, delivering services through 15 BDS-2 and 30 BDS-3 satellites. Since May 2023, five BDS-3 backup satellites have been launched to bolster system resilience.

    According to the monitoring data from the International GNSS Monitoring and Assessment System (iGMAS) and the International GNSS Service (IGS) in 2024, BDS achieves a service availability of 100% and exhibits a single satellite signal continuity of 99.991% per hour, with signal-in-space accuracy surpassing 0.9 meters (95%), broadcast ephemeris accuracy surpassing 0.2 m (95%), single frequency three-dimensional positioning accuracy of the B1C signal better than 6 m (95%, global average), and the B1C/B2a dual-frequency three-dimensional positioning accuracy superior to 3 m (95%). The timing accuracy is noted to be better than 10 ns (95%). The performance of the BDS PNT service has consistently met all performance requirements.

    Figure 1 illustrates the spatial signal accuracy of the BDS B1C signal. Figure 2 presents the broadcast orbit accuracy of the BDS B1C signal. Figure 3 showcases BDS’ global positioning accuracy for both single-frequency and dual-frequency.

    Through the BeiDou Satellite-Based Augmentation System B1C (BDSBAS-B1C) and the BeiDou Satellite-Based Augmentation System B2a (BDSBAS-B2a) signals, BDS offers single-frequency BDSBAS service that meets APV-I requirements and a dual-frequency multi-constellation service that meets CAT-I requirements for China and surrounding regions. The ionospheric grid model has been persistently refined to enhance the performance of the satellite-based augmentation services at the peripheries. Evaluation results reveal that the BDSBAS service attains a single-frequency positioning accuracy of 1.29 m (95%) horizontally and 1.99 m (95%) vertically, and a dual-frequency positioning accuracy of 0.77 meters (95%) horizontally and 1.41 m (95%) vertically.

    BDS disseminates precise orbit and clock difference corrections and inter-code biases via the precise point positioning (PPP)-B2b signal, providing PPP services to China and surrounding areas. Evaluation results indicate that the BDS-only precise point positioning accuracy is 0.16 m (95%) horizontally and 0.22 m (95%) vertically, with a convergence time of less than 20 minutes.

    In 2024, building upon its PNT services, BDS actively offers diversified specialized services, including regional short message communication, global short messaging, and international search and rescue. The number of user terminals for regional short message communications continues to grow. Based on inter-satellite links, global short messaging services can provide users with global random-access capabilities. These services have been applied in projects such as the Einstein Probe mission, the SVOM satellite in collaboration with France, and gravitational wave detection satellites, achieving instant return of global detection data. While six medium-Earth orbit (MEO) satellites are equipped with international maritime search and rescue payloads, the BDS return link enables transmission with a communication delay of less than 12 seconds, and a success rate of 96.82%, suitable for distress alert feedback, disaster information broadcasting and other multi-application scenarios.

    The stable BDS operation ensures the consistent and rapid improvement of application industries and the expansion of application scenarios. In 2023, the total output value of China’s satellite navigation and location-based service industries reached more than RMB 530 billion, marking a growth of more than 7% compared to 2022.

    2. System construction and development

    In May 2023, a backup geostationary orbit (GEO) satellite was launched, followed by two additional MEO backup satellites launched in December 2023, featuring upgraded global short message communication capacity and enhanced intelligent payload technologies. These backup satellites have successfully completed in-orbit testing and are now ready to provide services as needed. In September 2024, another pair of MEO backup satellites, equipped with innovative atomic clocks and a new type of inter-satellite links, were deployed. These backup satellites improve system reliability and service performance and facilitate experimental validation for next-generation satellite technology upgrades.

    To continuously enhance system service performance, BDS has developed precision and stability enhancement plans for both the ground control system and the in-orbit satellite support system. Efforts include intensifying satellite-based and ground-based multi-source data fusion analysis, conducting regular assessments of constellation and ground system statuses, and improving fault automatic diagnosis, response efficiency, and intelligence capacity.

    China is actively promoting the integrated development and experimental validation of BDS and LEO satellite navigation augmentation systems. Leveraging several test satellites within the under-construction LEO constellation, experiments including GNSS+LEO FPPP have been conducted. Results demonstrate that GNSS orbit determination accuracy is better than 5 cm (1σ), and clock error determination accuracy is superior to 0.15 nss (1σ). With signal enhancement from two to three LEO satellites, PPP positioning accuracy reaches 0.3 m with a convergence time at the minute level, thereby enhancing high-precision service performance and reducing PPP convergence time.

    In May 2023, China succesfully launched the first BDS-3 GEO backup satellite. (Photo: International Cooperation Center of China Satellite Navigation Office)
    In May 2023, China successfully launched the first BDS-3 GEO backup satellite. (Photo: International Cooperation Center of China Satellite Navigation Office)

    3. International coordination and cooperation

    China has been deeply involved in international satellite navigation. Since 2023, China has actively participated in a series of events under the United Nations framework, including the ICG-17 and the United Nations Workshop on the Application of Global Navigation Satellite Systems, contributing to the global advancement of satellite navigation. China has engaged in deep collaboration with system providers from the United States, Russia and the European Union to facilitate compatibility and interoperability, covering navigation signal structures, time systems, coordinate frameworks, test and assessment. Meanwhile, discussions are held with regional navigation satellite systems and emerging systems on topics of mutual interest, such as high-precision services and emergency alert services. In 2024, the BDS timing service was officially included in the Time Bulletin by the Bureau International des Poids et Mesures (BIPM), signifying international recognition of the ability to provide precise and reliable standard time services globally.

    China continues to expand its international partnership with BDS. In recent years, events including the BDS/GNSS Global Partner Forum, the China-Africa BDS Cooperation Forums, the China-Arab States BDS Cooperation Forums, the China-Central Asia BDS Cooperation Forums, the International Training Workshop on BDS Technologies and Applications in the Belt and Road Countries and Regions and the International Summit on BDS Applications have been held to share the benefits of BDS/GNSS applications globally.

    BDS will continue to uphold the vision of “a first-class navigation satellite system developed by China and dedicated to the world.” It will make every effort to ensure the stable operation, steady upgrades, and advancements of the system, as well as in-depth research in technologies such as low-orbit PNT and lunar PNT, furthering the commercialization, industrialization, and internationalization of BDS applications

  • Highlights and insights from ION GNSS+ 2024

    Highlights and insights from ION GNSS+ 2024

    The GPS World team participated in ION GNSS+ 2024, held at the Hilton Baltimore Inner Harbor, Baltimore, from Sept. 16-20.

    The event showcased more than 400 technical presentations spanning six sectors, addressing commercial and policy dimensions and research advancements. GPS World had the opportunity to engage in a series of discussions and panels, including a plenary session full of stories of space, and of circumnavigating the globe in a sailboat using only paper charts, a compass, and a sextant to navigate.

    (Photo courtesy of ION)
    (Photo courtesy of ION)

    Bob Addiss, senior software engineer at CAST Navigation, demonstrated CAST’s latest GNSS simulation systems. CAST GNSS systems can be configured to simultaneously provide multiple constellation types on each antenna element, such as GPS (including Y-Code, SAASM, M-Code AES and MNSA), BeiDou and GLONASS.

    (Photo courtesy of ION)
    (Photo courtesy of ION)

    Joshua Morales, StarNav CEO, led a demonstration of cold start positioning and timing using a StarNav receiver and simulated Xona PULSAR signals. The receiver tracked up to 13 PULSAR satellites simultaneously, producing real-time signal tracking and PNT data with a Safran GSG-8 simulator. This demonstration showcased StarNav’s receiver capabilities for LEO satellite-based PNT.

    (Photo courtesy of ION)
    (Photo courtesy of ION)

    More than 1,000 in-person attendees explored the show floor, visiting 44 exhibits. They had the opportunity to network, engage with exhibitors and dive deeper into the latest products and trends in the industry.

  • GNSS clocks prove to be invisible and indispensable

    GNSS clocks prove to be invisible and indispensable

    Photo: Safran; Getty Images: JTSorrell / iStock / Getty Images Plus (background), TommL / E+ (tv), yangphoto / E+ (power grid), Torsten Asmus / iStock / Getty Images Plus (finance), Michal Krakowiak / E+ (plane)
    Photo: Safran; Getty Images: JTSorrell / iStock / Getty Images Plus (background), TommL / E+ (tv), yangphoto /
    E+ (power grid), Torsten Asmus / iStock / Getty Images Plus (finance), Michal Krakowiak / E+ (plane)

    In the early 19th century, as the sun moved across Britain from east to west, people set their clocks to local mean time, so that noon in Greenwich would occur about 16½ minutes before noon in Plymouth. Back then, travel on foot, by horse, or by coach was slow and inconvenient, so having to adjust their pocket watch, for the few who even had one, was the least of travelers’ concerns.

    However, with the advent of railway travel, keeping track of time differences became confusing and impractical. In 1845, Henry Booth, a railway businessman involved with the Liverpool and Manchester Railway, petitioned parliament for a “Uniformity of Time,” arguing that when “the great bell of St. Paul’s strikes ONE, simultaneously, every City clock and Village chime, from John of Groat’s to the Land’s End, strikes ONE, also.”

    In addition to rail travel, advances in industrialization and automation also increasingly required time standardization, synchronization, and optimization. With the advent of satellite navigation, the requirement for accurate time reached the order of nanoseconds, because a signal delay of one nanosecond corresponds to roughly one foot of distance on the ground. This is why atomic clocks were one of the enabling technologies for GPS.

    In turn, atomic clocks on GNSS satellites became the most convenient way to calibrate and synchronize local clocks on the ground and to meet the stringent timing requirements of financial institutions, communication and broadcast networks, power utilities, transportation networks, weather radars, and a variety of scientific, commercial, military and consumer systems. Even though computer networks use PTP and other synchronization protocols, they all ultimately tie back to GNSS timing receivers to synchronize them to a global clock. This has made GNSS timing receivers ubiquitous and indispensable. Yet, the T in PNT (positioning, navigation, and timing) is invisible to most people and often an afterthought even for many of us in the industry.

    I discussed some of the challenges of GNSS timing with representatives of five companies:

    • Mark Tommey, sales director, Precise Time and Frequency
    • Paul Skoog and Eric Colard, senior technical engineers of product marketing, Microchip, frequency and time systems business unit
    • Jeff Gao, GM of communications, enterprise and data centers, SiTime
    • Farrokh Farrokhi, founder and president, etherWhere
    • Beacham Still, director of business development and operations lead, SyncWorks

    For the full transcripts of my interviews for this article, visit here.

    Positioning vs. timing

    The first step in using GNSS signals for time synchronization is to process them to extract pseudoranges in the same way as for positioning — except that the signal from a single satellite is usually sufficient, because the position of the phase center of the receiver’s antenna is determined once and for all when it is installed.

    However, most timing applications require much more accurate timing than positioning applications. “In GPS, let’s say that position accuracy is one meter with a clear view of the sky,” said Farrokhi. “That translates to a few nanoseconds of error. To achieve that over, say, a 24-hour cycle requires much tighter jitter on the receiver. So, the challenge for a timing application is to do a much better job of removing sources of errors compared to positioning. In the past, a requirement of 20 ns jitter in timing may have been enough for many applications. However, as the communication systems’ bandwidth and throughput increase, the requirement for timing becomes more stringent. We must come up with new algorithms and new architectures to reduce jitter and improve accuracy.”

    Another difference is that most timing receivers — such as those in a cellular base station — are stationary and connected to an antenna with a clear view of the sky. “There are methods to extract and remove most uncertainties and inaccuracies,” said Farrokhi.

    “Since it’s not moving, many satellites feed into the equations that help you solve the math to get you very accurate timing,” said Skoog.

    ”Finally, most GNSS positioning applications don’t require holdover, while for GNSS timing “holdover is a universal requirement,” said Gao, “ranging from four hours, for an edge data center or a small facility, all the way to 24 hours for a large cluster of servers or, in some extreme cases, even 48 to 72 hours for deployment in or near a hostile environment, where you expect jamming and all those bad things to happen.”

    Accuracy requirements

    etherWhere’s ew 6181 multi-GNSS timing receiver has a very low jitter across a wide range of temperatures.
    etherWhere’s ew 6181 multi-GNSS timing receiver has a very low jitter across a wide range of temperatures.

    The main critical applications for GNSS timing can be roughly grouped by the accuracy they require — but they are changing. “For example, for cellular systems up to 30 ns jitter used to be enough,” said Farrokhi.

    “As we move to 5G and 6G, this spec becomes tighter and tighter. We now must be below 5 ns for 6G. As we increase the bandwidth and must support higher throughput, we are more sensitive to timing inaccuracies.”

    “5G probably has the clearest requirement because you need 130 ns of relative time accuracy from one tower to another, mostly for handoff,” said Gao. “The accuracy requirements increase as you start to provide different services. For example, if different carriers want to aggregate some services, you start moving from 130 ns down to 65 ns, maybe even down to something more accurate.

    “Today, what’s driving the growth of our business is all in data centers and artificial intelligence (AI),” said Gao. “That ranges from traditional front-end server infrastructure and back-end AI workloads to edge data centers.” Timing requirements for data centers differ from those for other applications in terms of accuracy, reliability, and distribution to different locations, not all of which can have an antenna on the roof. “It’s a very interesting, multi-dimensional problem.”

    The requirements for financial services are defined in the United States by the Securities and Exchange Commission (SEC) and in Europe by the European Securities and Markets Authority (ESMA). To be legal, timing must have an audit trail all the way back to UTC and not diverge from it by more than 100 μs at the transaction level — the servers and the routers, said Gao.

    Additionally, in the United States, the Financial Industry Regulatory Authority (FINRA) requires financial institutions to be 50 ms to the National Institute of Standards and Technology (NIST). “That’s a hole so big you can drive a bus through it,” said Skoog. “However, if you want to trade on a stock exchange in Europe, you’re down to 100 µs. People typically will get a time server that will get them down to where they’re doing all their time stamping at better than a microsecond, but they put in a rubidium oscillator, so that if GPS goes away they can still finish that trading day and be better than 100 µs to UTC.”

    “For the bigger data centers there are no industry-wide standards,” said Gao. “Cloud service providers can each define their own requirements. What they care about is the window of time uncertainty: whether at the server level I have an error of 1 ms or 5 ms. You can go to 1 μs of error or down to 10 ns of error, each of which will enable you to provide a set of services. At 100 μs, for example, 99% of all your services are running. At 5 ms, you may have to start shutting down some services. More accurate time on the server also enables you to minimize the network traffic. So, conceptually, you can look at data center requirements anywhere from 5 ms all the way down to hundreds of nanoseconds, or even more accurate.”

    “Many markets have a lot in common, because they have communication networks,” said Colard. “For example, train and subway networks have communication networks very similar to those of telecoms. In the power industry, you have a communication network and a substation network. In the defense sector, you have confidential communication networks that are very similar to those from AT&T or Verizon. So, all these markets have the same requirements and the same features and challenges.”

    “Probably the number one reason why people put in a Stratum 1 NTP time server is to make sure that their log file time stamps are accurate,” said Skoog, “because that makes their network management systems more accurate and reliable.” However, accuracy is not the only concern. “The clocks are pretty accurate, but they connect to the network. All the network guys — the people who manage these networks — cannot plug this clock in until the security people give their stamp of approval.”

    Microchip Technology’s Precise Time Scale System (PTSS) is traceable to Universal Coordinated Time (UTC) and does not depend on GNSS.
    Microchip Technology’s Precise Time Scale System (PTSS) is traceable to Universal Coordinated Time (UTC) and does not depend on GNSS.

    Clocks and oscillators

    For all these accuracies, the key mechanism is GNSS timing. “In a typical data center,” said Gao, “you’re going to start with two grandmaster clocks, which are boxes that combine GNSS timing with locally accurate timing. That’s probably going to provide 5 ns to 10 ns of accuracy. More importantly, in addition to that, they have extremely good local oscillators that could be OCXOs, even some atomic clocks, that enable them to hold over if they lose GNSS timing for four, five hours, or 10 hours — up to 24 hours or 48 hours for a huge facility with many AI clusters.”

    Likewise, many financial services units don’t have GNSS antennas for every server, router and network card. “It just gets tremendously expensive to distribute the signal to each server,” said Gao, “because most of them are housed in huge warehouses that don’t have access to an antenna. They typically have a grandmaster clock.”

    “The GPS receiver itself is one product for all the segments that we sell into, but configured depending on how many timing outputs the customer wants and which frequency outputs,” said Tommey. “We also put a holdover oscillator into the unit that — if, for whatever reason, the GPS signal is lost — continues to provide valid time outputs for days, weeks, or even months.”

    “The advantage of GNSS is that over a long period of time it is extremely accurate,” said Gao. “The accuracy of an oscillator depends on how much holdover time you require. GNSS has a natural resolution of roughly 20 ns. At 5 ns, you start to rely on your local oscillator to do the next level filtering. For a base station or a core router, you need to get to 5 ns or better. So, you have GNSS native, you have an oscillator to do filtering to get a better accuracy and holdover, then you have network-based timing in a time scale of some sort.”

    “A data center, core network, or edge network never relies on a single source for timing,” said Gao. “GNSS is always viewed as extremely stable timing that everybody needs when you have access to the receiver and the antenna. Then you rely on the local oscillators and 1588 network timing as complementary technologies to ensure that you will always have timing all the time at a given accuracy.”

    Networks

    Increasingly, timing is distributed over a network. Some markets are more focused on Network Time Protocol (NTP), which has an accuracy of a few milliseconds, while others, such as telecoms, are more focused on Precision Time Protocol (PTP), which follows IEEE standard 1588 and is traceable all the way to a grand master somewhere. If someone just needs NTP, “it’s pretty easy to get 1 µs to 10 µs time accuracy between an NTP server and an NTP client,” said Skoog. “They may not even need 1 µs to 10 µs, but they’re going to take it if they get it, because log file correlation is very useful. Then when you get to PTP, it brings in a lot of hardware, time stamping and on-path assistance to get rid of some of that asymmetric delay. Now you’re down to sub-microseconds, and even approaching low nanoseconds. Then, if you must be down to 1 ns or something smaller, you’re into a 1 PPS application.”

    PFT3207A GNSS receivers in 1+1 configuration with a ptf1207A redundancy switch to provide timing and frequency reference signals to sub-systems in a satellite Earth station installation.
    PFT3207A GNSS receivers in 1+1 configuration with a ptf1207A redundancy switch to provide timing and frequency reference signals to sub-systems in a satellite Earth station installation.

    Jamming and spoofing

    Any infrastructure that must always be in service requires redundancy and resiliency. “We build rubidiums, cesiums, hydrogen masers and so forth,” said Skoog. “For years, the cesium was the domain of the metrologist. Those days have passed. Sure, metrologists buy them. But you need a plan B for what you’re going to do if GPS goes away, so you can connect pretty much all our products to a cesium clock.”

    When it comes to the impact of jamming and spoofing on timing, perspectives vary substantially between companies. “We’ve only ever had one customer who thought they’d been jammed or spoofed,” said Tommey. “We honestly don’t see very much of that at all.” However, according to Still, in the United States, a common problem is the proliferation of personal GPS jammers. “You see this through people with corporate vehicles and a fear of being tracked — similar to the rise of VPNs. Our power distribution systems, our substations, our telco central offices are in the communities they serve.” The problem arises, for example, “at substations located next to truck stops, night clubs, bars, all the different places that folks might not want to have pop up on their corporately tracked vehicles.”

    Often, when network operators see anomalies on their GNSS-based timing systems, it is challenging for them to identify and effectively mitigate the source of that interference. “You can naturally go to the site and try to do audits, and there are tools to try to measure and monitor this,” said Still. “What is more common and practical for network operators is designing and deploying their GNSS networks with the expectation that they’re going to encounter some form of interference.”

    Current wars have spurred great interest in distribution of timing over optical networks, said Colard. “Close to Russia, China, Israel, any of the conflicts in the world, there have been attacks on these networks every day. Spoofing is the main concern that I’ve seen. Anti-spoofing or anti-jamming are not enough. You need to find alternate time references for when GPS fails for any reason, so it’s an architecture discussion. For example, assisted partial timing support (APTS) has been used for years. It connects to other PTP grandmasters in the network and provides PTP input while GPS is down. Another alternative is to rely less and less on GNSS in general.

    “The alternative to using GPS receivers everywhere is to limit them to very specific strategic points and distribute time over optical networks,” said Colard. “There are segments of hundreds of kilometers in many countries without any GPS receivers. There are also enhanced primary reference time clocks (ePRTCs), which are usually connected to GPS and cesium clocks for resiliency. Often, carriers now are not even using GPS there. They’re using metrology labs and the national time coming from NIST or similar national time agencies as the time reference, instead of GPS, to limit the use of GPS as much as possible across the network.”

    A traditional GNSS-based clock for time-division multiplexing (TDM) services in a telecom’s central office.
    A traditional GNSS-based clock for time-division multiplexing (TDM) services in a telecom’s central office.

    Multipath

    As with the impact of jamming and spoofing, perspectives vary regarding the impact of multipath on timing. “We haven’t seen issues with multipath, except where users don’t do a good job of positioning their antenna or antennas,” said Tommey. Conversely, Gao said that “multipath is extremely relevant to timing. Let’s say, to give an extreme example, that you’re locking onto a single satellite. Depending on whether you have an unimpeded line of sight and no multipath or the signals are bouncing off a building, the difference could be 100 ns to 500 ns.”

    “Multipath might be a problem in a GPS antenna for timing, which usually sits on the roof,” said Skoog. “If you can keep this signal from reflecting up to the antenna in the first place with an adequate ground plane, that’s probably the singularly most effective thing you can do. I’ve been in GPS a long time. It used to be a very big deal. I never get asked about it anymore. It’s an old problem that’s sort of been solved.”

    Many people who have static antennas do not understand “that their sky view changes over the course of the year, and their visibility throughout the seasons and the winter solstice will be different than in the summer,” said Still.

    Transition

    The telecom industry is transitioning how it times and synchronizes networks from the time-division multiplexing (TDM) method that it has used for decades to IP and packet-based networks. “Particularly in TDM networks, the idea of UTC-traceable time of day was not really a focus until the advent of NTP, but ultimately it was all frequency synchronization,” said Still. “The idea was that if your network was in a frequency lock, and the phased alignment was good, your network would all drift together. So, TDM networks were also inherently synchronous, in a Synchronous Optical Networking (SONET) environment. You can distribute that frequency again throughout your network and pull it down from the overhead. By comparison, packet networks are inherently asynchronous, so it breaks the frequency chains that we’ve long relied on to distribute and synchronize our networks, and ultimately requires a new approach.

    “Modern networks and applications are increasingly reliant on precision time from GNSS-derived sources — high speed, low latency, high throughput, all being deployed to meet current and future needs,” said Still. This requires new sources of time, such as UTC-traceable time of day. Global networks and edge applications will all rely on time of day. “Not only are you trying to keep all your own networks synchronized, you must also have a relative accuracy to the rest of the world. So, some significant changes are taking place, particularly for engineers who have spent their whole career on TDM or SONET networks.”

    Now, Still said, “we can be more accurate using PTP on the edge than we can be with GPS. On the edge GPS now is an option. We keep those in place, distributed throughout the network, in case of bi-directional fiber cuts or losing some of the transport that we use to distribute precision timing, but you can be more accurate, more secure and more stable by using PTP than we can by relying on GPS.”

    Conclusions

    GNSS timing receivers are central to timing vast swaths of our industrial societies. Yet, as with positioning and navigation, growing concerns about jamming and spoofing are motivating some sectors to reduce their reliance on GNSS for timing and to develop alternative time references, including low-Earth orbit (LEO) satellites and eLoran. Meanwhile, many networks are transitioning to a new way of distributing timing.

  • First Fix: It’s time to give time its due

    First Fix: It’s time to give time its due

    Image: agsandrew/iStock/Getty Images Plus/Getty Images
    Image: agsandrew/iStock/Getty Images Plus/Getty Images

    Timing — the unglamorous yet essential T in PNT (positioning, navigation and timing) — has been called “the invisible utility.” In fact, it’s been a long time since we last put a GNSS-timing receiver on the cover. (Partly that’s because, like with simulators, it’s hard to come up with a visually compelling image that conveys the role of such a device.)

    From St. Augustine (“What, then, is time? If no one asks me, I know what it is. If I wish to explain it to him who asks, I do not know.”) to theoretical physicist Carlo Rovelli (who argues that time is “part of a complicated geometry woven together with the geometry of space”), time is both one of the greatest mysteries of nature and one of our most practical concerns. For satellite navigation, time is both essential to its functioning and a fabulous by-product. As David Wells and Alfred Kleusberg wrote in the first “Innovation” column, in the first issue of this magazine, “One of the by-products of getting an SPS [Standard Positioning Service] position fix is that a clock in the user’s receiver is automatically synchronized to clocks in the GPS satellites to an accuracy of one ten-millionth of a second. Therefore, any GPS receiver is a very accurate time distribution device.” (“GPS: A Multipurpose System,” January-February 1990.)

    As Richard Langley wrote in another early “Innovation” column, “Thanks to minute energy changes in individual atoms of cesium and rubidium, humankind possesses the ability to synchronize clocks anywhere in the world to better than 10 nanoseconds. But given this amazing ability to measure time, we still don’t know what time actually is.” (“Time, Clocks, and GPS,” November-December 1991.)

    I procrastinated the task of writing this editorial and now another aspect of time is here to impose its claim: our production deadline. So, just one anecdote and a final quote, and I will be done, just in time.
    The anecdote. A quarter century ago, during my first time around on this magazine’s staff, when Glen Gibbons was the group editorial director, Alan Cameron the senior editor, and I the managing editor, we had just one meeting a month, called “edit check,” a couple of days before the deadline to send each issue to the printer. We printed out all the pages, laid them down in order around a large conference room table, and walked around the table examining each one and making notes about small final corrections and revisions.

    Only one page routinely had a large empty area: It was the one for Glen’s monthly editorial, which he always finalized (wrote?) at the last possible moment. I once joked that it would be blown in at the printing plant like the magazine’s subscription cards. Well, as I finish this editorial, we are at T minus two days for the November issue. Enjoy it!

    Oh, and the final quote, again from Rovelli: “The events of the world do not form an orderly queue like the English. They crowd around chaotically like the Italians.”