GPS World

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  • Launchpad: GNSS receivers, timing modules, survey applications

    Launchpad: GNSS receivers, timing modules, survey applications

    A roundup of recent products in the GNSS and inertial positioning industry from the April 2023 issue of GPS World magazine.

    TIMING

    Image: Furuno Electric
    Image: Furuno

    Global Timing Module
    Supports L1 and L5 GNSS signals

    GT-100 is compatible with all GNSS constellations. The GT-100 realizes high robustness and standard of time accuracy and stability. The GT-100 features advanced multipath mitigation, anti-jamming and anti-spoofing as well as short-term holdover, ensuring superior performance even if L1 or L5 are jammed. The module delivers nanosecond precision for 5G wireless systems, radio communications systems, smart power grids and grand master clocks. Along with the GT-100, GT-9001 and GT-90 achieve a level of time stability of 4.5ns (1σ) and offer superior features and performance.
    Furuno, furuno.com

    Image: UTStarcom
    Image: UTStarcom

    PTP Grandmaster
    Designed for mobile networks

    The SyncRing XGM30E precision time protocol (PTP) grandmaster is designed for mobile networks and other applications requiring accurate time and frequency synchronization. It is an addition to the SyncRing line of network synchronization equipment. The SyncRing XGM30E is an indoor PTP grandmaster offering echo time accuracy of more than ±40 ns, which can meet the stringent timing requirements of demanding applications, including 4G and 5G networks. The clock complies with the PTP IEEE 1588-2008 standard, supporting major ITU-T frequency and phase and time profiles. SyncRing XGM30E supports synchronous Ethernet (SyncE) output on all service interfaces for accurate frequency synchronization, and SyncE input for enhanced time holdover operation during GNSS outages. The grandmaster includes an indoor rack-mount design and power supply redundancy with AC or DC built-in options and has flexible management options. The SyncRing XGM30E is available now.
    UTStarcom, utstar.com

    Photo: Huber+Suhner
    Image: Huber+Suhner

    Copper-Free Data System
    For precise timing synchronization for high-performance networks

    The GNSS and Power over Fiber GPSoF System receives, transmits and expands GNSS timing signals for the purpose of timing synchronization in data centers, central offices, distributed antenna systems or enterprise applications. It enables greater distances between the radio frequency source and the receiver system. It is also immune to RFI, EMI and EMP, contains remote control and monitoring via a web interface, and supports infrastructure installation due to direct GNSS signal evaluation.
    Huber+Suhner, hubersuhner.com

    Image: ADVA
    Image: ADVA

    M-Code Device
    With advanced timing for military applications

    The OSA 5422 grandmaster clock meets key requirements of military networks by providing advanced positioning, navigation and timing (PNT) capabilities and improved resilience. The OSA 5422 grandmaster clock is integrated with a highly reliable M-code receiver, which meets stringent frequency and phase synchronization needs. The device is equipped with multi-band, multi-constellation GNSS receivers for when M-code is not available. The OSA 5422 also has long holdover and precision time protocol backup, which enables it to maintain accurate timing even in the event of M-code disruption. The OSA 5422 supports legacy interfaces such as BITS and IRIG and features eight field-upgradable 10G bit/s ports and 1G bit/s interfaces. The device is suitable for most demanding military edge applications.
    ADVA, adva.com; Brandywine Communications, brandywinecomm.com

    AUTONOMOUS

    Image: CHC Navigation
    Image: CHC Navigation

    GNSS RTK Steering System
    Suitable for agriculture applications

    The NX510 SE Auto-Steer is an automated steering system that retrofits several types of new and old farm tractors and other vehicles. It can be connected to local real-time kinematic (RTK) networks or GNSS RTK base stations. NX510 SE is a guidance controller powered by multiple corrections sources and five satellite constellations: GPS, GLONASS, Galileo, BeiDou and QZSS. It has a built-in 4G and UHF modem that connects to all industry-standard differential GPS and RTK corrections to achieve centimeter-accuracy steering. NX510 SE contains GNSS and inertial navigation system terrain compensation technology, which maintains high accuracy in challenging environments and terrain. This makes NX510 SE suitable for ditching, planting and harvesting applications. In addition, AgNav multilingual software, operating on a 10.1 in industrial display, supports multiple guideline patterns that include AB line, A+ line, circle line, irregular curve and headland turn.
    CHC Navigation, chcnav.com

    Image: Trimble
    Image: Trimble

    Module for Rail Monitoring
    For automated and semi-automated rail monitoring

    The T4D Rail Module enables simple data collection and reduces office work required to automate movement detection for rail monitoring projects. The T4D software offers four main elements for automated monitoring: sensor management and data integration for GNSS; total station, geotechnical, vibration and environmental sensors; geodetic processing and adjustments for accurate results; analysis and visualization through several tools that provide real-time updates to support in-depth analysis and data presentation; and alarming and reporting. The T4D Rail module enables integration of rail as-builts collected with the Trimble GEDO system or with a track measuring bar paired with the Trimble Access Gauge Survey app. It also can automate calculations for track geometry parameters, generate analysis charts, and trigger alarms. The T4D software is offered in five editions to fit various project requirements. The editions include T4D Access, T4D Field, T4D Intermediate, T4D Geotechnical and T4D Advanced. T4D Access and T4D Advanced are the two editions that support the add-on Rail Module.
    Trimble Geospatial, geospatial.trimble.com

    Image: Airobotics
    Image: Airobotics

    C-UAV Device
    Anti-UAV protection device

    The Iron Drone system is an advanced counter-UAV device, designed to defend against hostile drones in complex environments with minimal damage. Iron Drone is an automated intercepting system designed to eliminate small drones without using GPS or radio frequency jamming. The Iron Drone system is launched from a designated pod and flies autonomously towards targets under radar guidance. It identifies the target using computer vision capabilities. The intercepting UAV follows the target then uses a net and a parachute to incapacitate it, capture it and lower it to the ground.
    Airobotics, airoboticsdrones.com

    R&S EVSD1000 has been designed to provide a mounting adaptor for installation onto medium-size drone types. (Image: Rohde & Schwarz)
    Image: Rohde & Schwarz

    Drone-based analyzer
    For UAV inspections

    EVSD1000 VHF/UHF nav/drone analyzer provides highly accurate UAV inspection of terrestrial navigation and communications systems. The EVSD1000 VHF/UHF nav/drone analyzer is a signal-level and modulation analyzer for medium-sized UAVs. It features measurements of instrument landing systems, ground-based augmentation systems and VHF omnirange ground stations. The mechanical and electrical design is optimized for UAV-based, real-time measurements of terrestrial navigation systems with up to 100 measurement data sets per second. The analyzer provides high-precision signal analysis in the frequency range from 70 MHz to 410 MHz. This also includes the needed measurement repeatability to ensure that results from UAV measurements can be compared to flight and to ground inspections in line with ICAO standards. The EVSD1000 VHF/UHF nav/drone analyzer reduces runway blocking times, provides necessary measurement repeatability and offers measurement precision and GNSS time and location stamps. While streaming measurement data during a drone flight via the data link to a PC on the ground, the analyzer can also buffer data internally to ensure no results are lost if the data link is lost.
    Rohde & Schwarz, rohde-schwarz.com

    SURVEYING & MAPPING

    SILC Eyeonic Vision System (Image: SiLC)
    Image: SiLC

    Coherent Vision Solution
    Suitable for advanced products

    The Eyeonic Vision System is a frequency-modulated continuous wave lidar solution, which delivers high levels of vision perception to identify and avoid objects with low latency. At the core of the system is a fully integrated silicon photonics chip. It provides more definition and precision than legacy lidar solutions, with roughly 10 milli-degree of angular resolution coupled with millimeter-level precision. These features enable this solution to measure the shape and distance of objects with high-precision and at a large distance. The system combines the Eyeonic Vision Sensor and a digital processing solution based on a powerful field-programmable gate array. The flexible architecture enables synchronization of multiple vision sensors for unlimited points per second. The compact, powerful, vision solution is suitable for autonomous vehicles, smart cameras, robotics and other advanced products. It is available now. Pricing varies depending on configuration.
    SiLC Technologies, silc.com

    Image: SBG Systems
    Image: SBG Systems

    GNSS-Aided INS
    Easily integrated with lidar or other third-party sensors

    Quanta Plus is a GNSS-aided inertial navigation system (INS). The device combines a MEMS inertial measurement unit (IMU) with a resilient GNSS receiver to get reliable position and attitude, as well as providing real-time kinematic (RTK) fixes. Quanta Plus includes motion profiles, which enable users to optimize the sensor parameters to suit different use cases. The built-in precise time protocol server ensures sub-microsecond synchronization with external devices such as lidar. The device also has a built-in datalogger, Ethernet interface for easy integration, and a web configuration interface for simple setup and control. The INS can be integrated with Qinertia, SBG System’s post-processing software. Qinertia improves the performance of acquired data during a mission using reliable RTK corrections from a wide range of continuously operating reference station networks, or by importing base-station data during the process. Quanta Plus also improves the accuracy of the position and attitude using forward and backward processing and by integrating a tight coupling between GNSS and IMU data.
    SBG Systems, sbg-systems.com

    (Image: Inertial Labs)
    Image: Inertial Labs

    Survey Laser
    Suitable for remote-sensing applications

    The Resepi Hesai XT32 laser is designed for accurate remote-sensing applications. It can be used with commercially available lidar scanners, including Velodyne, Quanergy, Ouster, RIEGL, LIVOX and Hesai, as well as with UAVs. Resepi is completely modular, so users have full control for customization. The remote-sensing device uses a GPS-aided inertial navigation system with a NovAtel RTK/PPK single- or dual-antenna GNSS receiver, integrated with a Linux-based processing platform. It also comes with a 2 TB USB memory drive and has an embedded Wi-Fi cellular modem. Resepi has 3 cm to 5 cm point-cloud accuracy and can reach heights of more than 200 m above ground level. It is compatible with most UAV models; however, it is typically used with DJI M300, DJI M210 or DJI M600 models. The device is suitable for scanning and mapping, precision agriculture with lidar, simultaneous localization and mapping algorithm development, utility inspection and construction site monitoring. Resepi-supported software includes Hexagon NovAtel, PCPainter and PCMaster.
    Inertial Labs, inertiallabs.com

    Image: CHC Navigation
    Image: CHC Navigation

    IMU-RTK GNSS Receiver
    Provides robust and accurate positioning

    The i90 GNSS receiver combines a GNSS real-time kinematic (RTK) engine, a high-end inertial measurement unit (IMU) sensor and advanced GNSS tracking capabilities to increase RTK availability and reliability. The embedded 624-channel GNSS receiver is compatible with GPS, GLONASS, Galileo and BeiDou signals. The i90 GNSS combines high-end connectivity modules: Bluetooth, Wi-Fi, NFC, 4G and a UHF radio modem. The internal UHF radio modem allows long-distance base-to-rover surveying up to 5 km. The built-in IMU ensures interference-free and automatic pole-tilt compensation in real time. An accuracy of 3 cm is achieved with pole-tilt range of up to 30°. The i90 GNSS receiver is suitable for construction and land surveying projects.
    CHC Navigation, chcnav.com

    Image: CHCNAV
    Image: CHCNAV

    Field Application
    For Android devices

    LandStar8 is designed to be flexible and user-friendly for surveying and mapping tasks. It is versatile, modular and customizable for topographic tasks such as surveying, stake out, cadastral, mapping and geographic information systems (GIS). Building on the legacy of LandStar7, the LandStar8 provides features such as a refined user interface, streamlined workflows, faster operation, and integrated cloud services. Cloud connectivity is built in for backup, data storage or remote technical support. LandStar8 has a simple and intuitive layout with large map windows and sharp graphics. Users can hide features they rarely use and display only those they need. They also can copy coordinate settings, control and staking points from another handheld controller by scanning a QR code. Projects can be edited and sorted by history and attributes. Custom coordinate systems, geoid models and coding libraries can be updated at any time by using resource packages. LandStar8 also features a terrain calibration wizard designed for non-expert users.
    CHCNAV, chcnav.com

    Photo:
    Image: Position Partners

    Survey Rover
    For accurate, survey-grade aerial mapping and photogrammetry

    SmartSurveyor facilitates accurate, survey-grade aerial mapping and photogrammetry without the need for a connection between a camera shutter and a GNSS receiver. The fully compact, handheld aerial mapping survey rover is compatible with DJI Mavix 2 and 3 series and Phantom 4 Pro UAVs. The design is dissimilar from other UAV mapping systems in that it works from a UAV or smartphone and with two or more ground control points (GCPs) while using an ultra-matching technique. Once SmartSurveyor captures data, all photos and the GNSS file are uploaded to a PC and analyzed through the Agisoft UltraMatch workflow to confirm their accuracy before they are exported. Data can be managed in the cloud or on a local PC using software designed by MapSender. Additionally, this mapping tool works in tandem with the AllDayRTK subscription GNSS network service so that collected data can be uploaded to Tokara to remotely manage a project.

    Position Partners, positionpartners.com

    OEM

    NB-IoT Industrial Module
    Complete with GNSS geo-location capabilities

    Image: STMicroelectronics
    Image: STMicroelectronics

    The ST87M01 is a fully programmable, certified LTE Cat NB2 NB-IoT industrial module that covers worldwide cellular frequency bands and integrates advanced security features. The ST87M01 is an integrated native GNSS receiver with multi-constellation access, which ensures enhanced and accurate localization. The module has a diminutive 10.6 mm x 12.8 mm land grid array footprint, making it suitable for applications where a small form factor is key. The STM8701 offers flexibility for product developers, presenting a fully programmable internet of things (IoT) platform enabling users to embed their own code into the module for simple applications. A variety of protocol stacks are available to handle popular IoT use cases. It targets wide-ranging IoT applications that require ultra-reliable low-power wide-area network connectivity and has ultra-low power consumption with less than 2 µA in low-power mode and transmit output power up to +23 dBm. Suitable applications for the module include smart metering, smart grid, smart building, smart city and smart infrastructure applications, as well as industrial condition monitoring and factory automation, smart agriculture and environmental monitoring. The module also can be combined with a separate host microcontroller, permitting many more use cases.
    STMicroelectronics, st.com

    Image: Quectel
    Image: Quectel

    GNSS Module
    Designed for battery-operated, ultra-low power GNSS devices

    The LC76G module is a compact, single-band, ultra-low power GNSS module that features fast and accurate location performance. The module can concurrently receive and process signals from the GPS, GLONASS, BeiDou, Galileo and QZSS constellations. The LC76G has an internal surface acoustic wave filter and integrated low-noise amplifier, which can be connected directly to a passive patch antenna and provides filtering against unwanted interference. With a compact size of 10.1 mm × 9.7 mm × 2.4 mm, the footprint of the LC76G is compatible with other industry solutions, as well as Quectel’s legacy L76 and L76-LB modules. The LC67G is designed for battery-operated, ultra-low power GNSS devices, such as wearable personal trackers, wildlife and livestock tracking, toll tags, portable container trackers, as well as several traditional markets such as shared mobility and low-cost asset trackers.
    Quectel Wireless Solutions, quectel.com

    The INS-DH-OEM. (Photo: Inertial Labs)
    The INS-DH-OEM. (Photo: Inertial Labs)

    Inertial Navigation System
    Incorporates NovAtel and Honeywell technology

    The INS-DH-OEM utilizes a dual-antenna NovAtel GNSS receiver and a Honeywell HG4930-CA51 inertial measurement unit (IMU). The INS-DH-OEM contains Inertial Labs’ on-board sensor-fusion filter, navigation and guidance algorithms, and calibration software. The INS-DH-OEM has three axes, a full operational temperature range, advanced MEMS accelerometers and new-generation tactical-grade MEMS gyroscopes to provide accurate position, velocity, heading, pitch and roll. It is small and lightweight, measuring 85.5 mm x 67.5 mm x 52.0 mm and weighing 280 g. The dual-antenna NovAtel GNSS receiver is operational with GPS, GLONASS, Galileo, BeiDou and QZSS constellations. The INS-DH-OEM is compatible with most commercially available lidars including Velodyne, Riegl and Faro. The algorithms are suitable for different dynamic motions of vessels, ships, helicopters, UAVs, gimbals and land vehicles.
    Inertial Labs, inertiallabs.com

    Image: MSO
    Image: MSO

    Speed Sensor
    Multi-use sensor for workflow

    The Speed Wedge MKII is a true-ground speed sensor and active motion detector for moving objects, based on radar doppler technology. This sensor is suitable for use in indoor and off-highway vehicles, conveyor belts, material flow and open channel water surface flow. The sensor contains a dead-reckoning system component for inertial measurement units and integrated management systems (IMS) in GPS/GNSS-denied environments such as in tunnels and underground mining operations. It also features sensor fusion with GNSS and IMS improving positioning accuracy, quality and reliability. Speed Wedge MKII deploys a radar front-end with planar antennas continuously emitting electro-magnetic waves at 24 GHz. It is designed for contactless measurement of speed and distance travelled independent on wheel/drive slip. For demanding applications Speed Wedge MKII is sealed and potted in a rugged encasing. Speed Wedge MKII is available in variants with pulse, serial RS232 and CAN-Bus output. High-speed up to 200 km/h is available.
    MSO, mso-technik.de/home-en.html

    Image: Orolia
    Image: Orolia

    GNSS Simulations Software
    For simulation and testing needs

    Skydel GNSS simulation software can now generate more than 500 simulated satellite signals. This platform is suitable for GNSS users, experts and manufacturers, as well as users needing a low-Earth-orbit-capable simulation system. Skydel contains a feature that includes multi-constellation and multi-frequency signal generation, remote control from user-defined scripts, and integrated interference generation. In addition to generating a high channel and satellite count, Skydel also can produce navigation warfare signals without any additional hardware.
    Orolia, orolia.com

    Image: Mikroe
    Image: Mikroe

    Compact Add-On Board
    Provides access to L-band GNSS corrections

    LBand RTK Click is a compact add-on featuring the NEO-D9S-00B, a professional-grade, satellite data receiver for L-band corrections from u-blox. Operating in a frequency range from 1,525 MHz to 1,559 MHz, the NEO-D9S-00B decodes the satellite transmission and outputs a correction stream. This enables a high-precision GNSS receiver to reach accuracies down to centimeter-level. An independent stream of correction data, delivered over L-band signals, ensures high availability of position output. LBand RTK Click also uses several mikroBUS pins. In addition, LBand RTK Click contains an SMA antenna for connecting a Mikroe-brand antenna. This antenna easily allows positioning in space, supporting GNSS L-band frequencies. LBand RTK Click implements advanced security features such as signature and anti-jamming mechanisms. It also can be integrated with other GNSS receivers from the u-blox F9 platform.
    Mikroe, mikroe.com

  • GPS technology helps communities across the globe

    GPS technology helps communities across the globe

    The C-130 Hercules aircraft is used to rapidly drop cargo to provide relief after disasters or troops into battle zones. (Image: USAF Devin Doskey- 341st Missile Wing Public Affairs)
    The C-130 Hercules aircraft is used to rapidly drop cargo to provide relief after disasters or troops into battle zones. (Image: USAF Devin Doskey- 341st Missile Wing Public Affairs)

    GPS Innovation Alliance (GPSIA) member companies are leaders in technology, transforming the digital and physical world around us. With countless essential applications, GPSIA members improve the industries that feed, build, move and connect communities across the globe. In times of need, the GPS industry is proud to rise to the occasion, whether through agriculture technologies, surveying equipment, navigation systems, essential communications tools, or humanitarian relief efforts. Simply put, GPSIA members are continually investing in lifesaving services at home and abroad.

    Take, for example, the urgent need for humanitarian relief created by the ongoing war in Ukraine. Trimble has stood united to support the many affected and displaced Ukrainians; in addition to contributing through the Trimble Foundation to relief efforts in Ukraine and neighboring countries, Trimble also has provided GPS signal corrections to Ukrainian farmers at no cost, supplied 3D scanners for surveying damaged buildings, and worked closely with The HALO Trust to support demining activities in Ukraine by providing funding and commercial surveying systems to assist in precision mapping of landmines and unexploded ordnances.

    Lockheed Martin’s C-130 Hercules aircraft has assisted essential humanitarian relief across the globe. Since its inaugural flight in 1954, this aircraft has enabled aid delivery, natural disaster relief, medevac services, search and rescue and more. Now equipped with GPS technology, the C-130 fleet has provided aid across the globe for decades — with L3Harris’ missionization solutions often at work to maximize the C-130’s utility. Similarly, Collins Aerospace’s state-of-the-art navigational technology has provided essential support to U.S. Coast Guard helicopters, with avionics upgrades that help pilots save time in emergencies and enhance situational awareness.

    Garmin inReach devices can send and receive messages, navigate routes, track and share journeys and can trigger an SOS if needed. (Image: Garmin)
    Garmin inReach devices can send and receive
    messages, navigate routes, track and share journeys and can trigger an SOS if needed. (Image: Garmin)

    More broadly, Garmin inReach satellite communication devices have helped more than 10,000 individuals access emergency services, providing critical communications in natural disasters and humanitarian emergencies. In 2022, a powerful underwater volcanic eruption and tsunami devastated the island nation of Tonga, severing traditional communications channels for several weeks. Roy Neyman, a sailor equipped with this Garmin device, set up a communication center at a local restaurant to allow other residents to reach family and friends. Over two weeks, Tonga residents sent about 1,600 messages to loved ones around the world, offering peace of mind in the face of unthinkable destruction. Similarly, Apple recently launched an “Emergency SOS” service, which led to one of the first successful rescue efforts of two people who had driven off a highway in the Angeles National Forest.

    CalAmp’s Fusion routers enable lifesaving emergency services to more than 400,000 residents in Oakland, California. Equipped with GPS, LTE and WiFi technology, these routers help Oakland Fire first responders quickly locate emergencies and access additional resources, such as building layouts or fire records, to provide the best possible emergency response. CalAmp’s technology provides an essential service to residents of Oakland and can be adapted to meet the changing needs of the community.

    As the world of agriculture has come to depend on GPS technology, John Deere’s GPS-based agricultural services have helped farmers become more efficient. In turn, this has allowed farmers to harvest more crops for the masses and meet the ever-growing demand for food. With the annual growth in food demand estimated to be 1.4% over the next decade, John Deere’s critical investment in food banks in Mexico and training for farmers in Africa will help to ensure that all communities are able to access the food they need.

    Across industries and government, GPS technology makes for a safer, more connected world. GPSIA is proud of its members’ dedication to global humanitarian efforts as well as critical services close to home. By constantly innovating, GPSIA member companies are creating technologies that provide critical services for everyday emergencies, natural disasters, and humanitarian crises across the globe.

  • First Fix: How GNSS helps farmers’ profits

    First Fix: How GNSS helps farmers’ profits

    Matteo Luccio
    Matteo Luccio

    Precision agriculture (PA) — which uses electronic information to better manage spatial and temporal variability in crops, livestock, forestry and other biological systems — is profitable, as proven by the rapid and widespread adoption of GNSS guidance for mechanized agriculture. Other enablers of PA include variable rate technology (VRT), remote-sensing using satellites and unmanned aerial vehicles, geographic information systems (GIS) and soil sampling.

    In my introduction to our January cover story, I requested pointers to any “independent, reliable and comprehensive study” as to PA’s return on investment. In response, Professor Won Suk Lee, of the Department of Agricultural and Biological Engineering of the University of Florida Gainesville, introduced me to Professor James Lowenberg-DeBoer, who has more than 30 years of worldwide experience in agricultural research, teaching, outreach and leadership and was the president of the International Society of Precision Agriculture. His research focuses on the economics of agricultural technology.

    Dr. Lowenberg-DeBoer wrote to me that “thousands of studies of profitability of precision agriculture” using “a wide range of methods and assumptions” arrive at “a relatively consistent set of conclusions.” He detailed them in a chapter on the economics of PA he wrote for a book published in 2019 (Precision agriculture for sustainability, edited by Dr. John Stafford, Silsoe Solutions, UK and published by Burleigh Dodds Science Publishing) and pointed out to me that additional studies of the topic conducted since then have not altered its conclusions.

    Lowenberg-DeBoer used adoption of PA as a proxy for its profitability, because, he wrote, “Farming is a business and technology is adopted if it provides benefits for the farmer and farm household.” He focused on PA for crops on relatively large-scale mechanized farms, but the same principles and general conclusions apply to livestock, forestry and other biological production systems and to medium and small farms.

    “Since GNSS guidance was introduced for ground-based agricultural equipment in the late 1990s,” he wrote, “almost all economic studies have shown positive economic benefits which could be quantified and substantial qualitative benefits which were more difficult to measure.”
    He reported that within about 10 years of the introduction of both lightbars and autosteer, GNSS was used by about 80% of the dealers. Adoption of PA sensors, on the other hand, was slower. “While GNSS guidance is being adopted quickly almost wherever agriculture is mechanized, VRT is more likely to be found in ‘hot spots’ where the profit potential and soil variability combine to motivate adoption.”

    Advances in autonomous robots will further revolutionize agriculture, Lowenberg-DeBoer predicted. “Implementing cropping tasks with swarms of small robots will change agronomic practices and the geography of agriculture. For example, with robotic pesticide application, it might be possible to spray each pest individually instead of broadcast application. This could reduce the amount of pesticide applied by [more than] 90% and reduce the negative effects on beneficial species.”

    For more on how GNSS is central to PA and how Lowenberg-DeBoer’s vision is beginning to take shape, see “Integrity Is Integral to Precision Agriculture.”

    Matteo Luccio | Editor-in-Chief
    [email protected]

  • Integrity is integral to precision agriculture

    Integrity is integral to precision agriculture

     

    THE TREKTOR HYBRID ROBOT for agriculture, made by the French company SITIA, can work on a variety of crops by changing the width of its wheelbase and can perform many repetitive tasks, such as spraying and hoeing. (Image: SITIA)
    The Trektor hybrid robot for agriculture, made by the French company SITIA, can work on a variety of crops by changing the width of its wheelbase and can perform many repetitive tasks, such as spraying and hoeing. (Image: SITIA)

    Precision agriculture has been around for more than 30 years and now covers the majority of U.S. farmland. It refers to the ability of farmers to observe, measure and respond precisely to the variability of soil and crop characteristics within and between fields by using maps of these characteristics and GNSS navigation. It enables them to reduce inputs of seed, water, fertilizer, pesticides and fuel while increasing outputs. It also enables them to work at night and in the fog and automate many functions at large feed lots.

    For precision agriculture, GNSS integrity can mean the difference between, say, a robot protecting a vineyard by weeding and spraying pesticides or damaging it by straying onto the vines.

    Autonomous Tractors, Mowers, and Feed Monitors

    SITIA, a French company, has developed an autonomous tractor that is used by, among others, an organic vineyard in France’s Loire valley to tirelessly weed the narrow rows between the grape vines — compensating for the movement of young workers to cities. Thanks to the high accuracy and integrity of the Septentrio GNSS heading receiver inside, the autonomous tractor has decreased the damage to the vineyards by more than an order of magnitude compared to the traditional work done by a farmer with a manual tractor.

    Renu Robotics, based in San Antonio, Texas, makes a robot for vegetation management, called Renubot. It uses machine learning, a form of artificial intelligence, to plan its route, optimize its energy consumption, perform self-diagnostics, collect environmental data and assess the topography that it traverses.

    Navigation is based on a stored map of paths, a Septentrio RTK GPS receiver and sensors to avoid obstacles. A radio link enables the Renubot to communicate with a control center, for reporting and updates. When the Renubot returns to its recharge pod, it charges its lithium battery and performs updates and downloads.

    Manabotix Pty. Ltd., an Australian company, has developed an automated system to monitor cattle in large feedlots, using GNSS, lidar scanning and other vision or perception technologies and artificial intelligence. This has greatly improved the accuracy and consistency of feedlot volume estimates, which for the previous 150 years had been the responsibility of a select few employees, who would visually gauge the amount of feed in concrete troughs. This visual inspection by humans was inherently imprecise, subjective, and inconsistent, often causing animals to eat too much or too little one day and get off their optimal growth curve or even become ill. Manabotix’s solution consists of a Septentrio AsteRx-U GNSS receiver and antenna, a lidar scanner, and an onboard processing platform.

    Statistical Analysis

    Integrity is a key aspect of all these applications. A part of delivering integrity is a statistical analysis called receiver autonomous integrity monitoring (RAIM), which was developed for such safety-critical applications as aviation or marine navigation. A refinement of RAIM, called RAIM+, takes this analysis to the next level as part of a larger positioning protection package.

    For autonomous operation, it can be particularly hazardous to be overly optimistic about GNSS accuracy. This parameter is reported in the form of positioning uncertainty, which is the maximum possible error on the calculated position. It is especially necessary in challenging GNSS environments, where the receiver has a direct line of sight to only a limited number of GNSS satellites or where GNSS signals are degraded. RAIM alerts users when their receiver’s uncertainty strays beyond the limits they have chosen for their application.

    Users can be deceived by a consistent position or movement — which can be consistently inaccurate. The positioning uncertainty gives them an indication of the extent to which they can rely on their receiver’s positioning accuracy at any given moment. The receiver operator can set an alarm limit, so that the receiver can flag situations when positioning uncertainty becomes too large.

    The blue line in Figure 1 shows position uncertainty estimated by a GNSS receiver under favorable conditions, when the view of the sky is unobstructed, and the receiver has a direct line-of-sight to many satellites.

    Figure 1. Under good GNSS conditions, the position uncertainty shown by the blue lines is well within the alarm limits, indicating safe operation. The actual position of the receiver should always remain within the blue uncertainty boundaries. (Image: Septentrio)
    Figure 1. Under good GNSS conditions, the position uncertainty shown by the blue lines is well within the alarm limits, indicating safe operation. The actual position of the receiver should always remain within the blue uncertainty boundaries. (Image: Septentrio)

    During favorable conditions, the positioning uncertainty stays well below the alarm limit because the calculated position is almost the same as the robot’s actual position. However, in challenging environments, the truthfulness of positioning uncertainty becomes most critical (see Figure 2).

    Figure 2. In challenging environments receivers with high integrity report large positioning uncertainty, flagging possible inaccuracies to the system. If the receiver is too optimistic about its accuracy, the operation becomes hazardous. (Image: Septentrio)
    Figure 2. In challenging environments receivers with high integrity report large positioning uncertainty, flagging possible inaccuracies to the system. If the receiver is too optimistic about its accuracy, the operation becomes hazardous. (Image: Septentrio)

    For instance, when the view of the sky is partially obstructed by buildings or foliage, the receiver has access to only a limited number of GNSS satellites, making it harder to calculate accurate position. In such cases the receiver must report a higher positioning uncertainty, so that the system can take adequate action such as switching to lower speeds, staying further away from predefined boundaries, or stopping.

    A low integrity receiver may keep reporting an optimistic positioning uncertainty, that stays below the preset alarm limit even when the calculated position is way off from the actual position. The number may look fine, but effectively it becomes a “robot on the loose,” no longer on its planned path with a risk of damaging itself and its surroundings.

    Let us look at uncertainty limits in action during a GNSS car test in an urban canyon, where the view of the sky is partially obstructed by houses (see Figure 3). The orange lines are the positioning and its uncertainty boundaries reported by a Septentrio mosaic GNSS module in the car, while the red lines are the positioning and its uncertainty boundaries reported by another popular GNSS receiver. The white line shows the actual position of the car as it drives along the road. The orange uncertainty boundaries of the mosaic receiver are truthful and somewhat wider in this challenging environment, and you can see that the actual position always remains within these boundaries. On the other hand, the red trajectory jumps off course in a certain challenging spot on the road, with the actual position no more within the uncertainty boundaries, which remain too optimistic. In this case the competitor’s receiver gives a false sense of security and the system is unaware of its hazardous operation.

    Figure 3: In an urban canyon car test the Septentrio receiver reports truthful position uncertainty. A competitor receiver seems to be more accurate, while the actual position is not even within its reported uncertainty boundaries. (Image: Septentrio)
    Figure 3. In an urban canyon car test the Septentrio receiver reports truthful position uncertainty. A competitor receiver seems to be more accurate, while the actual position is not even within its reported uncertainty boundaries. (Image: Septentrio)

    If the receiver depicted by the red line provided navigational information for an ADAS automotive system, for example, this could mislead the system into thinking that the car switched lanes. If the system then attempted to correct the trajectory by switching back to the “correct lane” this would result in taking the car off course and potentially hitting the sidewalk or even another car.

    RAIM vs RAIM+

    The underlying mechanism behind truthful positioning uncertainty reporting is RAIM, which ensures a truthful positioning calculation based on statistical analysis and exclusion of any outlier satellites or signals. Septentrio receivers are designed for high integrity and take RAIM to the next level with RAIM+, guaranteeing truthfulness of positioning with a high degree of confidence.

    In Septentrio receivers RAIM+ is a component of a larger receiver protection suite called GNSS+ comprising positioning protection on various levels including AIM+ anti-jamming and anti-spoofing, IONO+ resilience to ionospheric scintillations, and APME+ multipath mitigation.

    Septentrio has fine-tuned its RAIM+ statistical model with more than 50 terabytes of field data collected over 20 years. It removes satellites and signals which may give errors due to multipath reflection, solar ionospheric activity, jamming and spoofing, while working together with the GNSS+ components mentioned above. Because of this multi-component protection architecture, it achieves a very high level of positioning accuracy and reliability which goes well beyond the standard RAIM. The RAIM+ statistical model is adaptive, highly detailed, and complete, taking advantage of all available GNSS constellations and signals. The full RAIM+ functionality is also available in Septentrio’s GNSS/INS receiver line. User controlled parameters allow it to be tuned to specific requirements.

    The diagram in Figure 4 shows RAIM+ in action during a jamming and spoofing attack on a Septentrio GNSS receiver. While AIM+ removes the effects of GNSS jamming, both AIM+ and RAIM+ work together to block the spoofing attack. Satellites with high distance errors, shown on the middle graph, are removed by RAIM+ since they do not conform to the expected satellite distance.

    Figure 4. In this scenario jamming gives satellite distance errors but is countered by AIM+ technology. During spoofing AIM+ eliminates some of the spoofed satellites, while other satellites that have wrong distances are dismissed by RAIM+ algorithms. (Image: Septentrio)
    Figure 4. In this scenario jamming gives satellite distance errors but is countered by AIM+ technology. During spoofing AIM+ eliminates some of the spoofed satellites, while other satellites that have wrong distances are dismissed by RAIM+ algorithms. (Image: Septentrio)

    This example shows that even in the case of jamming and spoofing, Septentrio’s high integrity receiver technology delivers truthful and reliable positioning on which any autonomous system can count.

    GNSS Design Around Reliability

    GNSS receivers designed to be reliable strive for high integrity in both reporting of the positioning uncertainty as well as in RAIM+ advanced statistical modelling. This ensures that these receivers provide truthful and timely warning messages and are resilient in various challenging environments. Other technologies such as inertial navigation system (INS) can also be coupled to the GNSS receiver to extend positioning availability even during short GNSS outages. Quality indicators for satellite signals, CPU status, base-station quality and overall quality allow monitoring of positioning reliability at any given time. High-integrity GNSS receivers provide truthful positioning in autonomous machines such as the SITIA weeding tractor. They are also crucial components in safety-critical applications, assured PNT and any other application where accuracy and reliability matters.

  • Hexagon | NovAtel: Taking on land with SMART antennas

    Hexagon | NovAtel: Taking on land with SMART antennas

    One of a small army of PhytoPatholoBots (PPB) developed by Cornell University and deployed to four grape breeding programs across the United States. These autonomous robots will roll through vineyards, using computer vision to gather data on the physiological state of each grapevine. They use a NovAtel SMART antenna. (Image: Allison Usavage / Cornell University)
    One of a small army of PhytoPatholoBots (PPB) developed by Cornell University and deployed to four grape breeding programs across the United States. These autonomous robots will roll through vineyards, using computer vision to gather data on the physiological state of each grapevine. They use a NovAtel SMART antenna. (Image: Allison Usavage / Cornell University)

    One GNSS receiver widely used in autonomous ground vehicles is Hexagon | NovAtel’s SMART7 antenna. Matteo Luccio, GPS World’s editor-in-chief, discussed the product and its applications with Haley Lawrance, Senior Positioning Product Manager, Agriculture for Hexagon | NovAtel.

    Luccio: “How do you differentiate your SMART antennas from your other GNSS receivers?”

    Lawrance: “The reason why the SMART antenna portfolio has been so attractive within the agriculture market and to our autonomy customers specifically, has been the ease of integration and the high performance it provides. GNSS positioning is just one part of an autonomous system, and the autonomous integrators don’t necessarily have the volume of machines out of the gate that would justify the development time for them to integrate the OEM components.

    With NovAtel’s SMART antennas, they only need to consider the single cable harness that will run power and communications to and from the receiver – and a single mount point on the vehicle. The SMART antennas offer a waterproof and rugged enclosure, designed to withstand the demanding environments typical for agriculture – and help accelerate our customers’ time to market.”

    Luccio: “Is there some standard, as there is for cars, that enables developers of autonomous systems to easily plug your system into theirs?”

    Lawrance: “We support a variety of communication protocols – serial, CAN, Ethernet, and Wi-Fi. For autonomy, Ethernet tends to be the most common option for communication with the GNSS receiver – especially when using features that require more bandwidth, such as our SPAN GNSS+INS sensor fusion solution that leverages an inertial measurement unit.

    NovAtel’s_OEM7_driver, built for the Robot Operating System (ROS), is a great option because it makes it even quicker for them to integrate and allows the receiver to essentially plug-and-play into the ROS environment with minimal development. For CAN, we support both J1939 Transport and Extended Transport Protocol and NMEA 2000 if they would like to communicate onto an existing bus they are using on the vehicle.”

    Luccio: “What about the ease of integration on the software side?”

    Lawrance: “We have a very large library of proprietary NovAtel-formatted logs that are available in binary and ASCII, which provide flexibility and allow customers to customize a unique set of logs that provide the data they are interested in. This could be anything from information on which satellites are being used in the solution, to the roll and pitch of the vehicle, or status information from the receiver. NovAtel receivers also output in standard formats, such as NMEA 2000 and NMEA 0183, that consolidate the data that they are most likely to need, such as position, velocity, and quality indicators.”

    Luccio: “What markets do your SMART antennas target?”

    Lawrance: “Broadly speaking, the SMART antenna product line was designed specifically for agriculture use cases and environments. Customers include agriculture OEMs, aftermarket integrators that develop retrofit precision ag solutions, and autonomous solution providers.
    Within that product line, we have SMART7 and SMART2, with different performance options that allows us to scale the best product solution for each application. For high-performance semi-autonomous or autonomous applications that need centimetre-level accuracy – even in highly variable terrain and challenging GNSS-obstructed environments, SMART7 is the best fit – together with SPAN GNSS+INS and TerraStar-C PRO Correction Services or RTK.

    For additional positioning redundancy on an autonomous vehicle, SMART2 can be used together with SMART7 – meaning there are two different, independent GNSS hardware, software, and positioning solutions running in parallel. This allows autonomous machinery manufacturers to utilize both positioning solutions in parallel for an additional layer of protection.”

  • Autonomous systems take on more tasks

    Autonomous systems take on more tasks

    Image: Renu Robotics
    Image: Renu Robotics

    While on public roads self-driving cars are still years away, autonomous systems are already common in much less congested and/or much more controlled environments — such as farm fields, ports, mines, rivers, and in the air — where the risk of a collision causing injuries or fatalities is smaller by orders of magnitude. From unmanned aerial vehicles (UAVs) taking aerial photographs, to unmanned ground vehicles (UGVs) spraying vineyards, to unmanned surface vessels (USV) conducting hydrographic surveys, autonomous or semi-autonomous systems are generally much safer, more efficient, and cheaper to operate than their manned counterparts.

    Whether they have wheels, hulls, or wings to properly perform their tasks, autonomous systems need to know — with great accuracy — their position, heading and attitude (roll, pitch, yaw, surge, sway, and heave). For example, to spray grapes in a vineyard, an autonomous system needs to know not only its exact position but also whether it is level or tilted to one side due to uneven terrain, lest it spray the ground or into the air instead of the grapes. Similarly, a survey vessel’s pitch, which depends on its speed through the water, and its roll, due to waves and wind, affect the direction of its sonar beams.

    Knowing a platform’s position, heading and attitude requires tight integration of the outputs of GNSS receivers and inertial navigation systems (INS). This enables autonomous systems to compensate for their movements — either physically and in real time, by orienting their sensors or tools, or in software when post-processing the data they collected.

    The following three case studies sample current developments in autonomous systems on land, in the air, and on the water.

    — Matteo Luccio, Editor-in-Chief

    Learn more about the following case studies:

    ON LAND
    Hexagon | NovAtel: Talking on land with SMART antennas

    IN THE AIR
    Trimble Applanix: Unmanned aerial vehicles aid survey efforts

    ON THE WATER
    CHC Navigation: The boat boost

  • Trimble Applanix: Unmanned aerial vehicles aid survey efforts

    Trimble Applanix: Unmanned aerial vehicles aid survey efforts

    L’avion jaune, a French UAV and aerial photogrammetry company, uses the Trimble Applanix APX-20 UAV GNSS-inertial OEM solution and a YellowScan VX-20 lidar on its M600 multirotor UAV. (Image: L’Avion Jaune)
    L’avion jaune, a French UAV and aerial photogrammetry company, uses the Trimble Applanix APX-20 UAV GNSS-inertial OEM solution and a YellowScan VX-20 lidar on its M600 multirotor UAV. (Image: L’Avion Jaune)

    The breakdown of limestone cliffs generates landslides and loose debris that threatens the environment, people and wildlife below. These conditions make it impossible to safely operate traditional survey equipment from the ground for landslide detection. Using UAVs for direct georeferencing is an efficient way to take traditional survey efforts to the sky and enables users to accurately assess land formations while mitigating risk.

    One way to implement direct georeferencing on UAV platforms is with the Trimble APX-20 UAV, which is a GNSS-inertial OEM solution that increases the mapping efficiency of small UAVs. It consists of small, low power, precision GNSS and inertial hardware components and POSPac UAV post-mission differential GNSS-inertial office software. The APX-20 UAV eliminates the need for ground control points and reduces the sidelap required to be flown per flight.

    The APX-20 UAV contains a precision, survey-grade GNSS receiver and dual inertial measurement units (IMU), so it automatically supports integration on gimballed platforms without requiring an external interface to an autopilot or on a mount. It computes at 100 hz using the embedded IMU while simultaneously logging the raw IMU data from both the internal and external IMU at 200 hz for post-processing in POSPac UAV. The postprocessed position and orientation solutions are suitable for direct georeferencing of cameras, lidars and other sensors.

    Trimble Applanix UAV Put to the Test

    For fast and safe landslide detection, the Trimble Applanix APX-20 UAV for direct georeferencing was put to the test using a Multirotor M600 manufactured by French company L’Avion Jaune equipped with a VX-20 lidar sensor made by YellowScan, also a French company. This combination produces cost-effective and reliable high-resolution UAV lidar-derived DTMs and 3D models for hazard mitigation and planning.
    L’Avion Jaune has performed more than 600 successful mapping missions globally. After pursuing mapping activities with mainly crewed aircraft, it began developing UAVs for long-distance applications for marine, tropical forest and polar regions such as the Multirotor M600/YellowScan VX-20, which offers high-precision, cost-effective and efficient aerial mapping.

    The APX-20 UAV and the M600/YellowScan VX-20 were combined and deployed to evaluate landslide activities in France. The mission parameters for this configuration included: high point density; x, y, z precision of 5 cm; access to dangerous zones; map generation under dense vegetation area, and fast deployment. The goal of this project was to enable the implementation of safety and prevention plans for the protection of pedestrians, infrastructure, wildlife and more.

    During the six-hour duration of the project, the APX-20 UAV and M600/YellowScan VX-20 configuration was flown four times for 15 minutes each during sunrise. It flew more than 75 ha in surface area with a flight speed of 5 m/s at 60 m in the air, following the topography. Checkpoints were surveyed with differential GPS following the conclusion of the flights. Data processing included computation of the georeferenced trajectory, matching flight lines and point cloud classification, which took two days.

    The Results

    The flexible UAV deployment of resources enabled the acquisition of dense point clouds and the generation of DTM in less than three days. During this project L’Avion Jaune was able to optimize the choice of material and discover the best practices to collect and process lidar data for mapping in dense vegetation.

  • CHC Navigation: The boat boost

    CHC Navigation: The boat boost

    To improve the efficiency of their hydrographic surveying services and expand them, Coastal Geomatics evaluated multiple USV, choosing the CHC Apache 4. (Image: Coastal Geomatics)
    To improve the efficiency of their hydrographic surveying services and expand them, Coastal Geomatics evaluated multiple USV, choosing the CHC Apache 4. (Image: Coastal Geomatics)

    Time (and costs) saved using unmanned surface vessels (USV) over conventional methods for hydrography can be dramatic — especially in autonomous mode. Numerous firms, large and small, have discovered how modest investments in such craft can completely revolutionize their hydrographic operations. One such firm is the family owned and operated Coastal Geomatics in North Carolina.

    “With conventional methods, it used to take us four weeks with a three- or four-person crew to do the bathymetry for 26 canals that we do every two years for the City of Holden Beach,” Chris Stanley, owner and manager of Coastal Geomatics, said. “Now, with our Apache we do this over four days of high tide; about four to five hours per day.”

    Stanley had been surveying in the local area for more than 30 years and had partnered in several local firms. In 2020, he decided to start his own firm, together with his two adult sons Alan and Ian: Coastal Geomatics was born.

    “We do a lot of boundary work, and topographic surveys as there is a lot of construction going on in the area,” Alan said. “We also do flood insurance work, FEMA elevation certificates, and hydrographic work — we are on the coast.” Holden Beach is on one of North Carolina’s barrier islands, separated from the mainland by the Intercoastal Waterway. Coastal Geomatics has standing contracts to do hydro work for FEMA beach erosion annually, and the biennial canal surveys for the city.

    The move to a USV for hydrographic surveys made a lot of sense, however a past bad experience with the technology prompted Stanley to be extra diligent in choosing a boat. At one firm for which the elder Stanley had worked in the past, they had acquired a USV that he said was essentially “a jet ski, with a mix of components cobbled together.” He added that they had never really gotten it to work right, and it now sits idle in a storage unit.

    The Stanleys did some research on the current state of small USV, noting that some still seem like “contraptions” and decided instead to test out three models from CHC Navigation: the Apache 3, 4, and 6. They had considered the tri-hulled Apache 6 for some offshore work they sometimes do, however, they chose the Apache 4 for now. It has a dual GNSS antennas for position and heading that is tightly coupled with an IMU for uninterrupted positions, a single beam echo sounder, and a 360° camera. It has a sensor well that can accommodate most of the popular models of acoustic doppler current profilers (ADCP), though Coastal Geomatics is not presently using an ADCP. It can be run fully autonomously for missions defined in the AutoPlanner software, or remotely piloted — Coastal Geomatics needed both options. They noted how the boat is compact, easy to operate, and all components are well integrated with watertight seals.

    For open water areas of their contracted surveys, they put the USV in full autonomous mode, where they say it is quite efficient. However, there are specific tasks where a remote pilot needs to take over.

    The canals surveyed for the city to inform dredging operations are about 100 feet wide and each house has a floating dock. There is a 20- to 30-foot strip between the docks. The old method, Ian explained, was to put one of the crew in a small flat bottomed Jon boat, with a crew member on each side of the canal, often with a fourth using a total station. Points across the canal from bulkhead to bulkhead were taken with a long prism pole, handing the pole off to the crew member on the other side after each crossing. The dynamics of which residents’ boats might be at the docks on any given day made full autonomy for that phase of the surveys impractical.

    Coastal Geomatics’ solution was to employ a peddle-powered kayak, guiding the Apache remotely. The flexibility of their new craft has enabled the firm to execute multiple types of surveys and expand their hydrographic services more efficiently.

  • Seen & Heard: Can GPS forecast rain?

    Seen & Heard: Can GPS forecast rain?

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

    Image: Licence plate, Reviver
    Image: Reviver

    Digital license plates gone wrong

    A security research team has gained administrative access to Reviver, the only company in California that sells digital license plates, which has allowed them to track the physical location of all of Reviver’s customers. With this vulnerability, anyone could remotely update, track and delete someone’s Reviver plate. The access also enabled the researchers to change a section of the text at the bottom of the plate, designed for personalized messages, to anything they want, according to Vice.com. California launched the option to buy a digital license plate in October 2022, and Reviver has since addressed the license plates’ security vulnerability.

    AirTag. (Image: David Peperkamp/iStock / Getty Images Plus/ Getty Images)
    Image: David Peperkamp/iStock / Getty Images Plus/ Getty Images)

    Bill makes secret tracking illegal

    Indiana state legislators have filed a bill that would make tracking someone with a GPS-based device without their knowledge a crime, reported WTHR of Indianapolis. The bill is in response to the growing number of criminal cases involving Apple AirTags and other GPS-based tracking devices. Tracking someone secretly is not currently a crime in Indiana; however, laws vary from state to state. Under the proposed bill, the penalty would be increased from a Class C misdemeanor to a Class A misdemeanor if the person tracked is under a protective order. The penalty could be enhanced for someone convicted of using a tracking device when committing a felony. Similar incidents are on the rise around the United States involving the use of AirTags and other tracking devices for criminal purposes.

    Image: big-dan/ iStock / Getty Images Plus/ Getty Images
    Image: big-dan/ iStock / Getty Images Plus/ Getty Images

    Cellphones cause demise

    On New Year’s Day, six rockets were launched from a United States-made Himars rocket system at a vocational college in Ukraine, killing at least 89 Russian soldiers. Russia is blaming this on illegal cellphone usage by Russian soldiers, defying a ban. Ukrainian officials say 400 Russian soldiers were killed and another 300 were wounded, contradicting Russia’s report. However, this is the largest number of deaths Russia has acknowledged during the war. Russia says that the obvious cause of the attack was the use of mobile phones, as the enemy was able to locate and determine the troops’ coordinates for the strike. Two of the rockets were shot down before reaching Makiivka in the occupied Donetsk area of Ukraine. 

    Image: Angelo F-/ iStock / Getty Images Plus/Getty Image
    Image: Angelo F-/ iStock / Getty Images Plus/Getty Image

    Can GPS forecast rain?

    Researchers at the Department of Marine Geology and Geophysics at the Cochin University of Science and Technology in Kochi, India, say that heavy rainfall can be detected more than six hours in advance using GPS signals, reported The Hindu. During rainy seasons, as GPS signals pass through the atmosphere, how much they are delayed depends on the amount of water vapor present. By using continuous GPS signals and rainfall data collected in Thiruvananthapuram, the study showed that any heavy rainfall could be detected using this delay. 

  • Research roundup: Space and lunar applications

    Research roundup: Space and lunar applications

    The Moonlight initiative will provide sustainable lunar data-relay services for communication and navigation around the Moon. (ESA Moonlight Study conceptual drawing.) (Image: SSTL/Airbus/ESA)
    The Moonlight initiative will provide sustainable lunar data-relay services for communication and navigation around the Moon. (ESA Moonlight Study conceptual drawing.) (Image: SSTL/Airbus/ESA)

    GNSS researchers presented hundreds of papers at the 2022 Institute of Navigation (ION) GNSS+ conference, which took place Sept. 19–23 in Denver, Colorado, and virtually. The following five papers focused on lunar and space applications. The papers are available now.

    MTO Navigation Using Lunar Signals

    The moon transfer orbit (MTO) is becoming increasingly important as several national space agencies are planning moon exploration soon, with projects such as NASA’s Artemis. In previous research, the GPS navigation accuracy on the MTO reached 200 m at the moon altitude by using GPS signals emitted from the far side of Earth. As accuracy on a low-Earth orbit (LEO) using GPS is a few meters, 200 m accuracy is not accurate enough to support lunar exploration. The deterioration of accuracy is due to the poor geometry of the GPS satellites that became visible from the MTO.

    The authors want to achieve an accuracy of less than 100 m in MTO by using other navigation sources, including the lunar navigation satellite system (LNSS) to be deployed in the moon’s orbit. The LNSS signals will come from the far side of the moon, similar to the signals of GPS satellites coming from the opposite side of Earth. Its satellites will be pointed towards the moon to provide positioning, navigation and timing services on the moon surface, especially at the lunar South Pole region

    The researchers have been conducting the simulation evaluation for the MTO navigation accuracy using signals coming from the moon and assume that these signals will be emitted from beacons on the moon surface or the LNSS.

    Murata, Masaya; Kogure, Satoshi; “Moon Transfer Orbit Navigation Using Signals Coming from the Moon.”

    Designing the Smallsat-Based LNCSS

    There is growing interest in the use of a smallsat platform for the future lunar navigation and communication satellite system (LNCSS); however, many design considerations are not finalized for the smallsat-based LNCSS, such as choice of the satellite clock, satellite orbital parameters and the constellation size.
    Using the Systems Tool Kit simulation software, the authors examined various LNCSS constellation case studies based in elliptical lunar frozen orbit and with a low-grade chip-scale atomic clock.

    They evaluated case studies of navigation design considerations including position and timing accuracy, lunar user equivalent ranging error, and dilution of precision. As for case studies of communications design considerations, the authors examined daily data volume, availability and data rate. Finally, they examined smallsat factors including the cost, size, weight and power of the satellite payload.

    The paper includes trade-off analysis in satisfying the preliminary design criteria outlined by international space agencies and commercial space companies.

    Bhamidipati, Sriramya; Mina, Tara; Sanchez, Alana; Gao, Grace; “A Lunar Navigation and Communication Satellite System with Earth-GPS Time Transfer: Design and Performance Considerations.”

    Developing an SDR for Space

    A geostationary satellite (GEO) equipped with the satellite-based augmentation system (SBAS) function has a transmitter for GNSS correction signals at the L1 and L5 bands. This transmitter could interfere with the GNSS space service volume (SSV) receiver in the same satellite, so L1 and L5 signals cannot be used for the GEO SBAS satellite. However, the use of GPS L2C signals can be an alternative.

    The authors of this paper present the development of a GPS L2C signal generator for the SSV in GEO simulation. They present the simulation process for GEO satellites and the structure of the GPS L2C signal generator.

    In this study, a verification through the receiver test with a GNSS software-defined receiver is included to show the possibility of the designed signal simulator. The validation is performed by analyzing the programmable system device, the results of the acquisition, code/carrier tracking, and the C/N0 estimation.

    Lee, Hak-beom; Choi, ByeongHyun; Song, Young-Jin; Won, Jong-Hoon; Kwon, Ki-Ho; “Development of GPS L2C Signal Generator for SSV in Geostationary Orbit Simulation.”

    Differential Positioning on the Moon

    This paper introduces a new concept of delivering the pseudorange correction calculated at a reference station on the lunar surface, as a part of the lunar navigation satellite system (LNSS) navigation message. The concept enables LNSS users to apply differential positioning using pseudorange correction without adding new hardware to their receivers.

    The authors propose the differential positioning technique to reduce the signal-in-space range error of LNSS satellites and the coordinate transformation errors from Earth-centered fixed frame to lunar reference frame — the dominant errors in satellite positioning by LNSS.

    The proposed reference station is equipped with instruments to externally estimate its own position relative to the lunar reference frame. The user on the lunar surface would then perform differential positioning using the station coordinate and pseudorange correction obtained at the reference station.
    In this study, the simulation results using eight elliptical lunar frozen orbit satellites show that the real-mean-squared values for both horizontal and vertical positioning errors with differential correction are reduced to 1/10 of those without differential correction, even at 10 degrees latitude from the reference station at the lunar South Pole.

    Akiyama, Kyohei; Murata, Masaya; Kogure, Satoshi; “Differential Positioning Performance on Lunar South Pole Region Using Lunar Navigation Satellite System.”

    GEO Precise Orbit Determination

    Using GPS in satellites in geostationary (GEO) orbits provides advantages by improving position, velocity and timing data, reducing operating costs and providing autonomous orbit control for station keeping. This paper presents the result of the onboard data evaluation and precise orbit determination of an optical data-relay satellite (ODRS) using GPS L1 C/A code and carrier-phase observations for 74 days.

    As a result of precise orbit determination, the authors found that both code- and carrier-phase observations are affected by the ionospheric delay when signals pass through the plasmasphere located above the ionosphere.

    Several methods were implemented during this research to reduce the effect of the plasmasphere, including setting a higher cut-off altitude, applying correction sequences generated from orbit determination residuals, and applying a new observation noise model depending on the GPS off-nadir angle. Results show that the correction sequences and the new noise model improve the internal orbit consistency. The authors also found that the orbit bias in radial direction due to negatively biased carrier-phase observations is mitigated from –51 cm to –17 cm by setting a higher cut-off altitude and applying correction sequences.

    Matsumoto, Takehiro; Sakamoto, Takushi; Yoshikawa, Kazuhiro; Kasho, Sachiyo; Nakajima, Ayano; Nakamura, Shinichi; “GEO Precise Orbit Determination Using Onboard GPS Carrier Phase Observations of Optical Data Relay Satellite.”

  • Positioning through walls: DHS and NASA partner on indoor positioning and location solution

    Positioning through walls: DHS and NASA partner on indoor positioning and location solution

    NASA-JPL prototype of POINTER base units on a first responder vehicle. The magneto-quasistatic fields they generate can be detected through walls, where legacy indoor positioning technologies fail. (Image: Jet Propulsion Laboratory)
    NASA-JPL prototype of POINTER base units on a first responder vehicle. The magneto-quasistatic fields they generate can be detected through walls, where legacy indoor positioning technologies fail. (Image: Jet Propulsion Laboratory)

    A tragedy in 1999 spurred development of an entirely new type of positioning and location technology. “This project started with the Worchester, Massachusetts, warehouse fire,” said William Stout, program manager for the Department of Homeland Security (DHS) Science and Technology Directorate (S&T). “Six firefighters went in to clear an abandoned warehouse that was on fire to make sure there wasn’t anybody in there, and they got trapped. The team couldn’t find them because they had no idea where they were, and they ended up perishing.

    That is what got DHS started with developing a first responder location tracking technology, Stout said.

    “Over the years from that point on, we investigated many different technologies. My predecessor referred to most of these as ‘cocktail solutions’ because they would try to merge different types of technologies — for example, GPS and inertial — but none of these panned out.”

    Enter Magnetoquasistatics Research

    This lack of progress changed in 2012 when they connected with Darmindra Arumugam, group supervisor, senior research technologist and program manager at NASA’s Jet Propulsion Laboratory (JPL). Caltech manages JPL for NASA. In a complete departure from traditional radio signal-based positioning technologies, Arumugam and his team had been researching magnetoquasistatics (M/QS). This is the foundation for the POINTER System.

    The system consists of fixed or portable transmitters, for instance, a base unit and controller that can be mounted on a first responder vehicle outside of a building. The first responders carry a small receiver that the base can locate with two characteristics: the field’s strength (for ranging) and its unique pattern (for lack of a better term) for direction (receivers send position info back to the controller via ISM band LoRa). The controller registers and displays the position of each receiver.

    Why Magnetic Fields?

    Ranging can be done in many modes, Arumugam said, and not all are based on just the amplitude of the propagating wave. With traditional radio signal ranging, to compute a precise position, techniques mostly use multiple sources of signals, for trilateration or multilateration, as GNSS does. However, signals can be perturbed by objects in their path, or experience multipath (signals bouncing off objects), which is a pronounced challenge for indoor environments.

    The portable POINTER receivers can be clipped by first responders to their belt, harness, or personal protective equipment, reporting their position in a building, and viewable by an incident commander on a laptop. (Image: Gavin Schrock)
    The portable POINTER receivers can be clipped by first responders to their belt, harness, or personal protective equipment, reporting their position in a building, and viewable by an incident commander on a laptop. (Image: Gavin Schrock)

    POINTER does not employ radio signals in the fashion of traditional ranging solutions such as GNSS, ultra-wide band (UWB), and various beacon systems for indoor positioning. However, Arumugam said POINTER does generate a radio signal.

    “The key difference is that we are detecting the field in a regime where there is no radio propagation mode. Therefore, it is more accurate to refer to this as a quasi-static field, as opposed to a radio propagating wave,” Arumugam said.

    Arumugam said Earth’s magnetic field is a good example of this. “It penetrates structures very well, we can measure it 100 kilometers beneath the surface, far above the surface, inside buildings, underwater and so on,” he said. “POINTER uses the kind of the features that you see in Earth’s magnetic field — we are generating quasi-static magnetic fields.

    “The term quasi-static highlights the fact that we are trying to keep the physics of the field stationary for all purposes but apply some slow time variation so that it’s really quasi-static to optimize the benefits from both,” Arumugam said. “We get the best of the behaviors of static fields in terms of penetration and non-line-of-sight capability, but also optimize for signal-to-noise by making this a quasi-static signal as opposed to a perfectly static one.”

    JPL developed for DHS S&T prototypes that the two organizations tested jointly. Both transmitters and receivers employ an array of three coils, oriented at right angles for x, y and z. The resultant transmitted field carries distinct patterns from these three axes. Distance is detected from field strength, and direction is determined by detecting the pattern of the field relative to the three axes. A key strength of POINTER is that it can achieve ranging and direction from a single base station.

    However, Arumugam noted that multiple bases could be beneficial for certain situations.

    “The technique as originally developed requires only one transmitter. However, we find that there’s only so much you can get out of a magnetic field, and certain types of structures and materials will perturb that field, causing error.” The second transmitter is not only a backup, but it also helps reduce errors.

    POINTER

    Geolocation Inc. was spun out from Caltech to license and commercialize POINTER, said Joseph Boystack, executive chairman and co-founder. “We stepped in and executed an exclusive worldwide license for every field of use on this technology in late 2020 from JPL. They had established a proof of concept, and begun testing the technology in the field.”

    For the initial commercial version, Balboa Geo made significant improvements over the JPL prototype system. It developed two transmitters that can be deployed on a fixed-mounted basis (buildings, vehicles, ships, etc.) or be portable housed inside a ruggedized, military specification (MIL-STD) case, with a built-in dual antenna GNSS receiver (to position and orient the transmitter).

    “If you have an incident involving first responders, military or industrial applications, these remotely configured transmitters can be quickly and easily deployed,” Boystack said. “Also very important, because it only needs to depend on the field generated by the transmitter, we’re not dependent upon other large, fixed infrastructure such as satellites, towers or beacons, and can work in degraded environments where most other position, navigation and timing techniques fail.”

    The self-contained receivers are only about the size of a smartphone. The orientation of the receiver is important to determine the “xyz” axis relative to the generated field, thus providing highly accurate three-dimensional position and navigation data. For instance, Balboa Geo’s receiver can be clipped to a first responder’s belt, harness, or personal protective equipment. Similarly, for fixed assets or moving assets such as warehouse systems or robotics, the orientation would be known.

    The POINTER system will generate real-time data that can be easily visualized at the job site or event by the incident commander or manager on a laptop or a tablet. The data is interoperable and may be ingested in third-party software applications.

    This version meets DHS STS’s original expectations, and subsequent versions will build on it. “S&T relies on experienced emergency response and preparedness professionals to guide our research and development. The First Responder Resource Group is made up of hundreds of state and local volunteers,” Stout said. “We initially looked at tracking firefighters in some of the most common scenarios: two-story house fires.”

    While POINTER technology has the potential for much longer ranges and precisions, the current version, Arumugam said, certainly meets the specifications for this initial application. “The current systems can operate up to about 75 meters in range from the transmitter. So, if a transmitter is placed about 10 meters outside the building, say on the fire truck, you can penetrate up to about 65 meters inside the structure. That covers many one, two, maybe three-story structures. Position accuracies can be one meter or less. In principle, you could get to a centimeter, but that’s not required for this technology to be the lifesaver it presently needs to be.”

    JPL continues research and development to extend range and increase precision to enable DHS S&T to deploy this technology to ever broader safety-of-life applications where legacy technologies fall short or are completely impractical. Balboa Geo is conducting field and lab tests for many more applications across multiple industries including energy, construction, maritime, mining, the internet of things and more.

  • Monitoring earthquakes, eruptions and avalanches to mitigate risk

    Monitoring earthquakes, eruptions and avalanches to mitigate risk

    On Feb. 6, a magnitude 7.8 earthquake struck Turkiye and northern Syria creating enormous damage throughout both countries.
    On Feb. 6, a magnitude 7.8 earthquake struck Turkiye and northern Syria creating enormous damage throughout both countries. (Image: mustafaoncul/iStock /Getty Images Plus/Getty Images)

    Geographical information of urban areas is critical because it forms the basis for planning, intelligent urban modeling and disaster mapping and management. For many decades, ground surveys and aerial photographs were used as the primary tools for collecting this data. Starting in the 1990s, these methods were replaced by such advanced remote-sensing technologies as synthetic aperture radar (SAR) and ground-based interferometric radar (GBIR).

    This article explores the use of software-defined radio (SDR) platforms for acquiring high-resolution SAR/GBIR images, including:

    • How low-cost commercial-off-the-shelf SDR platforms can be used to realize complex systems for acquiring images and processing measurements.
    • How different specifications of SDRs make them suitable for use in SAR applications.

    Hazard Monitoring in Urban Areas

    Many urban areas and critical infrastructure are in regions highly prone to natural disasters such as volcano eruptions, earthquakes, avalanches and landslides, or near man-made systems such as dams and quarries. Monitoring of surface changes and structures is integral to the mitigation of risk and ensuring public safety. Modern remote-monitoring systems allow surface displacements to be monitored without the need to access a location. With these systems, several square kilometers of Earth’s surface can be monitored at once and with high accuracy. The sub-millimeter accuracy of modern remote-monitoring technologies enables accurate measurements to be collected with impressive precision, including in rainy and foggy conditions.

    Remote-monitoring systems are autonomous and can operate for a long time without human intervention. Their real-time feedback makes them suitable for use as early-warning systems. In addition, these monitoring systems can be integrated into a wide range of sub-systems, such as decision support systems that assist decision makers in assessing emergency plans and selecting the best options.

    Using Radar to Measure

    Details of the surface observed by a SAR satellite are encoded in the amplitude and phase of a SAR image. The amplitude component contains information about the surface roughness and terrain slope of the target area, while the phase component contains information about the elevation of the satellite.
    A typical SAR satellite transmits microwave signals toward a target area at an oblique angle and measures the backscattered signal. The intensity of the reflected signal is mainly determined by the roughness and the structure of the target, and the distance between the satellite and the target. This measurement is usually described in terms of the radar cross-section (RCS) parameter, which is obtained by calculating the ratio of the scattered to the intercepted signals as shown in this equation:

    Equation PNT Ca

    The RCS parameter is mainly dependent on the surface roughness and the dielectric properties of the target object.
    The interferometric SAR (InSAR) technique allows surface movements to be identified. These observations also can be used to measure and monitor changes associated with volcanic eruptions, tectonic activity and other geophysical processes. To identify crustal changes using this geodetic technique, at least two SAR images are required.

    Figure 1. Phase shift in InSAR observations due to ground movement.
    Figure 1. Phase shift in InSAR observations due to ground movement. (Image: Simon Ndiritu)

    In differential InSAR, two images of the same location that are recorded at different times are used. If a surface movement has occurred between the first and the second acquisition, a phase shift is observed (Figure 1). The presence of interference fringes on an interferogram is an indicator of a phase shift and these fringes are summed during processing to provide a relative value of the phase change.

    Ground-based SAR (GBSAR) employs the synthetic aperture radar technique to capture high-resolution images of the electromagnetic reflectivity of a target. This remote-sensing system is commonly used for monitoring civil infrastructure, buildings, mines, landslides, glaciers and more. While spaceborne SAR is capable of surveying large areas and records data over long periods of time, usually several weeks or months, GBSAR is suitable for monitoring small areas and has short sampling periods, usually a few minutes. In most surveying applications, the two remote-monitoring techniques are used together in a complementary fashion to enhance the overall performance.

    The all-weather monitoring capability of satellite-based SAR makes it a popular tool for natural disaster management. Since the launch of the first SAR satellite in 1991, this technology has provided many emergency response teams with important insights on manmade and natural hazards. SAR data can be used to study different aspects of long-term behaviors of slow-moving surfaces, which is critical for planning emergency response to natural hazards such as volcanic eruptions, landslides and avalanches. SAR satellites orbit Earth at altitudes of between 500 km and 800 km and operate in the C-band (5 GHz to 6 GHz), X-band (8 GHz to 12 GHz) and L-band (1 GHz to 2 GHz). The temporal resolution of these satellites is mainly determined by their revisit periods.

    Software-Defined Radio Platforms

    A typical SDR platform features a radio front end (RFE) and a digital back end, with the RFE performing receive (Rx) and transmit (Tx) functions and offering a wide tuning range, typically 0 GHz to 18 GHz. This range is acceptable for widely used bands in SAR applications, including L-band, C-band and X-band.

    The digital back end of a high-performance SDR system features a field programmable gate array (FPGA). This FPGA offers a variety of digital signal processing (DSP) capabilities, including upconverting, downconverting, modulation and demodulation. In addition, an SDR platform offers multiple transmit and receive channels, making it suitable for implementing multi-in multi-out (MIMO) radar systems.

    The architecture of SDR platforms allows them to integrate easily with a wide range of complex systems, such as SAR systems. The reconfigurability of SDRs allows upgrades and updates to be implemented without modifying the existing hardware, and can be designed to meet the size, weight and power (SWaP) requirements of an application. These features make SDRs suitable for implementing custom SAR monitoring solutions in small and large ground stations (Figure 2).

    Figure 2. A simplified diagram of an SDR-based SAR system is shown, which employs a mobile-transmitter fixed-receiver passive bistatic SAR (MF-PB-SAR) architecture. (Image: Simon Ndiritu)
    Figure 2. A simplified diagram of an SDR-based SAR system is shown, which employs a mobile-transmitter fixed-receiver passive bistatic SAR (MF-PB-SAR) architecture. (Image: Simon Ndiritu)

    Integrating SDRs with SAR

    A software-defined radar (SDRadar) is an SDR-based radar system that offers high flexibility and robustness. Compared to conventional radar, SDRadar offers many benefits, including the opportunity to reuse hardware, develop multi-function radar solutions, achieve faster development cycles, and have easier implementation of updates and new algorithms.

    Tests with prototype SDR-based GBSAR systems have revealed the strong potential of SDR-based implementations. The MIMO architecture of an SDR platform allows realization of complex multi-frequency GBSAR systems uniquely suited for measuring displacement and other geophysical characteristics of landforms. SDR-based GBSAR systems can operate in different frequency bands and offer unmatched flexibility when it comes to signal generation and digital signal processing.

    Many prototypes of airborne/satellite SAR systems based on SDR platforms have been implemented and their performance evaluated. Results have shown that they can offer better performance compared to conventional implementations. The use of multiple independent channels by SDR platforms allows the realization of compact and power-efficient multimode SAR systems, while the architecture of an SDR platform allows complex signal processing techniques such as digital beamforming (DBF), null steering and direction of arrival estimation to be implemented on FPGA.

    Benefits of Integrating SDRs with SAR Solutions

    Integrating SDRs into SAR systems provides many benefits. The MIMO architecture of SDR systems provides more channels than are required for SAR functions. The extra channels can be used for other applications such as satellite communications during emergencies. The wide frequency-tuning range of an SDR system allows the realization of a multi-function system with applications using different frequency bands. The reconfigurability of SDR platforms allows them to be repurposed for other applications. In addition, this reconfigurability enhances reusability, scalability and power efficiency. The low-latency FPGAs in high-performance SDR systems allow the realization of ultra-high-speed DSP algorithms for use in image processing and DBF.

    Conclusion

    The reconfigurability and impressive performance features of SDR platforms make them ideal for implementing scalable and flexible SAR monitoring systems for measuring land changes. The wide tuning range and MIMO architecture of SDR devices allows realization of a multi-function and multi-frequency system using a single device. In addition, the reconfigurability of SDR devices allows hardware reuse and low-cost implementation of updates and new algorithms.

    Brendon McHugh is the field application engineer and technical writer at Per Vices. He possesses a degree in theoretical and mathematical physics from the University of Toronto.

    Simon Ndiritu is an independent technical writer for Per Vices with a background in electrical and electronic engineer with a wealth of experience in designing hardware and firmware. He also has a passion for writing.