James D. Litton, GPS pioneer and founder of NavCom Technology Inc., died over the weekend at his home in California with his family at his side. He was 89 years old.
Litton was an early contributor to the development of GPS user equipment. He also played a pivotal role in the GPS-driven transformation of global agriculture that has greatly benefited humanity.
Litton was the director of engineering at Magnavox Research Labs when researchers were working on using CDMA for range measurements, a precursor to the GPS system. He also worked on the original proposal for GPS Phase I.
Later, as general manager of Magnavox’s Marine and Survey Systems Division, he helped develop new and advanced commercial navigation and survey receivers for both the Navy’s TRANSIT system and the Air Force’s GPS.
His team developed the first microprocessor-based commercial satellite navigation receivers and the first commercial GPS survey software. This led to Magnavox eventually having more than a 90 percent share of the survey receiver market.
The firm eventually held more than two dozen patents for improvements in GPS technology.
In 1992, Litton left Magnavox to start a consulting business. Two years later, with Ron Hatch, K.T. Woo and Jalal Alisobhani, he founded NavCom Technology Inc. With Litton as CEO, NavCom became a significant player in the GPS marketplace. Among its achievements was development — under contract — of a single-frequency WAAS-capable GPS aircraft navigation receiver.
NavCom also began a relationship with Deere & Company, supporting more efficient and productive agriculture. This relationship was so successful that Deere purchased NavCom in 1999. Litton continued to lead the company and serve as part of Deere’s senior management team for eight more years.
In recognition of his many achievements to the field, Jim Litton was presented the Institute of Navigation’s Hays Award in 2006.
Among his many contributions, his impact on global agriculture might well have been his greatest, according to Brad Parkinson, the original chief architect for GPS.
“His work transformed agriculture into a data-driven, technological industry that was incredibly more efficient,” Parkinson said. “The cost savings and increases in productivity have impacted billions around the world.”
Jim’s family has created a memorial fund at Doctors Without Borders for those wishing to make a donation in honor of his life and many good works. Click here.
The European Commission has issued industrial contracts worth €1.47 billion ($1.97 billion) to build next-generation Galileo satellites to Airbus and Thales Alenia Space, reports BBC News.
Both companies told BBC News that they will not speak publicly about their contracts wins until documents are signed, which could take several weeks.
Each contract is for manufacture of six satellites, to orbit no earlier than 2024. They will feature digitally configurable antennas, inter-satellite links, new atomic clocks and propulsion systems that use electric engines.
Airbus and TAS built the four Pathfinder in-orbit validation satellites that first demonstrated Galileo. A consortium of OHB-System and Surrey Satellite Technology Ltd. built the first operational Galileo satellites, but the consortium ended following Brexit.
Responding to letters from industry, National Security Institute (NSI) Executive Director and Professor Jamil Jaffer said he determined that three of the issues raised, while not fatal to the document, warranted clarification.
ELoran callout. The first was a statement in the backgrounder that the National Timing Resilience and Security Act (NTRSA) “specifies 13 technical requirements for a GPS backup, which essentially define the eLoran system.”
This was a concern to some on the hill as Congress is generally reluctant to specify solutions. Legislators prefer to specify outcomes and then defer to the executive branch on how to make them happen.
Members of industry pointed out that government systems like WWVB and the low-frequency portion of DARPA’s STOIC program, as well as commercial systems like NextNav and Locata, could meet or be adapted to meet the NTRSA requirement.
The revised backgrounder says the NTRSA “specifies 13 mainly technical requirements for a GPS back-up, which align closely with the capabilities of the eLoran system. Other systems may meet the Act’s requirements to varying degrees.”
Multiple technologies. The revised backgrounder also corrects a statement that the NTRSA requires the Department of Transportation to establish an eLoran system. It now says “a system that complies with the Act, and DOT may pursue multiple technologies in implementing the Act.”
Department officials had previously said they were taking a system-of-systems approach and expected to employ multiple technologies. Subsequently, a DOT report was released that documents the need for several diverse systems. It lists transmissions using low frequency (eLoran, STOIC), ultra high frequency (NextNav, Locata) and L-band from space (GPS, Satelles). It also says the terrestrial transmitters should be interconnected by fiber.
Public-private partnership. A third correction was made in the document to reflect how the Congressional Budget Office regarded the possibility of using a public-private partnership in previously proposed legislation.
Members of industry also expressed concern that one of the authors of the document serves on the advisory board for Satelles Inc. and that this was not disclosed in the paper. The backgrounder appeared on the Satelles website the same day it was published.
The university concluded that such disclosure was not necessary as the paper said the author “provides advisory services to industry, including in the PNT area.” At the author’s request, though, his profile on NSI’s webpage will be updated to show his relationship with Satelles.
Senate joined House to override Trump’s veto, making bill into law
The U. S. Congress, especially the Armed Services Committees, have long been concerned about GPS and positioning, navigation and timing (PNT) issues. Over the past two decades, Congressional hearings, demands for reports and investigations have dealt with acquisition, contingency plans for when space is not available, deliberate interference, and a host of other issues.
While these all evidenced Congress’ interest and concern, they were relatively passive measures.
This began to change in 2018 with passage of the National Timing Resilience and Security Act. It requires the Department of Transportation to establish a terrestrial timing system to backup GPS signals.
Then in 2019, Congress appropriated money for a GPS Backup Technology Demonstration. And the National Defense Authorization Act (NDAA) for 2020 required the Air Force to develop a prototype multi-GNSS receiver as part of its resiliency efforts.
The NDAA for 2021 seems to finalize Congress’ transition from an interested observer, mostly on the sidelines, to an active player in national PNT issues and policy.
GPS Under Threat
Capitol Hill observers say this is the result of several factors that have come to a head over the last year. Taken together, they have convinced many legislators that GPS is under threat and PNT issues are not being taken seriously enough by the executive branch. These include increased jamming and spoofing (especially by China and Russia), full implementation of China’s BeiDou system and its marketing to other nations as a superior alternative to GPS, the Federal Communications Commission’s (FCC) decision on Ligado Networks, and the Pentagon’s failure to respond to combatant commanders’ Joint Urgent Operational Needs Statements for non-GPS PNT.
Here are some of the provisions of the 2021 NDAA of interest to the PNT community.
Military Multi-GNSS Prototype
The 2018 NDAA required the Defense Department to incorporate Europe’s Galileo and Japan’s QZSS satellite navigation signals into military user equipment. The idea was to make it more resilient to disruption. Also required was an investigation into using non-allied signals.
Apparently not satisfied with progress on this project, Congress mandated a project to develop a prototype multi-GNSS receiver as part of the 2020 NDAA.
The 2021 NDAA seems to indicate Congress is still not happy. It withholds 20% of the funding for the Office of the Secretary of the Air Force until the department certifies the prototype project is underway and provides briefings to the Senate and House Armed Services Committees.
Resilient, Survivable PNT
Language in the 2021 NDAA also seems to show Congress is impatient with the Pentagon’s lack of responsiveness to combatant commanders’ requests for non-GPS PNT systems.
Section 1611 of the act is entitled “Resilient and Survivable Positioning, Navigation, and Timing Capabilities.” It requires development, integration and deployment of these capabilities for combatant commanders within two years. This, it says, is “… consistent with the timescale applicable to joint urgent operational needs statements…”
The act says the new PNT capabilities shall “generate resilient and survivable alternative positioning, navigation, and timing signals” and “process resilient survivable data provided by signals of opportunity and on-board sensor systems…”
The act also addresses the Defense Department’s 2018 PNT Strategy’s plan for future systems to be classified and for military use only. It directs the department to work with the National Security Council, Departments of Transportation, Homeland Security and others “…to enable civilian and commercial adoption of technologies and capabilities for resilient and survivable alternative positioning, navigation, and timing capabilities to complement the global positioning system.”
To help ensure prompt action on this, the act requires a report to Congress within six months and authorizes the department to reprogram funds from other areas to finance the effort.
Responding to Ligado Decision
By far the most PNT-related text in the 2021 NDAA includes a host of measures responding to FCC Order 20-48 approving an application by Ligado Networks. An order that the executive branch is on record as strongly opposing, saying it will degrade GPS service for many.
Senator Jim Inhofe, chair of the Senate Armed Services Committee, has regularly expressed outrage at the FCC’s decision and has called for its reversal.
Among its provisions, the act:
requires the Department of Defense to estimate and report to Congress the cost of damage to department systems as a result of the FCC order.
prohibits using department funds to upgrade or modify military equipment to make it resilient to interference caused by broadcasts in the spectrum allocated (the FCC order requires this to be funded by Ligado).
prohibits contracting with any entity using the frequency bands allocated to Ligado unless the Secretary of Defense certifies the use will not interfere with GPS services.
requires the Secretary of Defense to contract with the National Academies of Sciences, Engineering, and Medicine for an independent technical review of the FCC order.
Dana Goward is president of the Resilient Navigation and Timing Foundation (rntfnd.org).
Trimble has introduced the Trimble AX940 and AX940i high-precision GNSS smart antennas, designed for a broad range of high-precision applications such as precision agriculture, milling machines in construction, forestry harvesting equipment, autonomous vehicles, port automation and mobile mapping.
With multi-frequency, multi-constellation support for GPS, Galileo, GLONASS, BeiDou, QZSS and NavIC, the smart antennas can deliver reliable centimeter-level accuracy in a variety of environments. In addition, the Trimble AX940 and AX940i provide reliable, high-accuracy positioning without the constraints of a local base station or cell modem by using Trimble RTX correction services.
Built-in inertial sensors on the AX940i allow a tight integration with GNSS observations in the RTK/RTX positioning and orientation engine, providing continuous high-rate low-latency output to guidance and control systems.
“The new AX family of smart antennas delivers the latest GNSS and inertial technology in an easy-to-integrate and rugged form factor,” said Thomas Utzmeier, general manager for Trimble OEM GNSS. “Reliable, robust and compact, the smart antennas are an ideal option for OEMs and system integrators to easily and quickly add high-accuracy positioning to their applications.”
The Trimble AX940 and AX940i provide flexible interfaces with high-speed data transfer and configuration; simplified integrations reduce development times; and an intuitive 3D graphical web page allows easy input of the lever arm for easier set up.
The full-featured smart antennas are equipped with 336 channels for multi-constellation support; Trimble RTX and OmniSTAR support; flexible RS232, USB, CAN and Ethernet interfaces; and advanced RF spectrum monitoring. The AX940i also includes Wi-Fi and Bluetooth connectivity for wireless interface and control.
Using the latest Trimble Maxwell 7 Technology, the AX940 and AX940i are designed with flexible signal management that enables the use of all available GNSS constellations and signals.
The Trimble AX940 and AX940i smart antennas are expected to be available in the first quarter of 2021 through Trimble’s OEM GNSS Sales Channel.
In a report issued on Jan. 14, the Department of Transportation (DOT) outlined the results of its GPS Backup Technology Demonstration project. As officials had previously projected, it called for a system-of-systems approach using multiple complementary technologies.
The report called for an architecture that included signals from space in the L-band, terrestrial broadcasts in the ultra high frequency (UHF) and low frequency (LF) spectra, and a fiber backbone to synchronize and feed precise time to terrestrial transmitters.
The demonstration project and report were mandated by Congress in legislation passed in late 2017 and funded in early 2018. Delays within the administration resulted in the project beginning in early 2019.
Monty Johnson of OPNT demonstrates precise time transfer through 100 kilometers of spooled fiber-optic cable. (Photo: RNT Foundation)
Demonstrations
Of 21 firms that offered to demonstrate their wares, 11 were selected. They were:
Echo Ridge LLC and Satelles Inc. Satellite-based PNT technologies using the S and L bands, respectively.
OPNT B.V. and Seven Solutions S.L. Fiber-optic time transfer using the White Rabbit Precision Time Protocol technology.
TRX Systems Inc. Dead reckoning technology with inertial measurement units and localized map matching supplemented with ultra-wideband beacons.
Hellen Systems LLC and UrsaNav. eLoran that uses LF transmissions.
Serco Inc. Medium frequency R-mode.
NextNav LLC. Metropolitan beacon system using UHF frequencies.
PhasorLab Inc. and Skyhook Wireless Inc. Both use Wi-Fi frequencies. Phasorlab uses a dedicated network of transmitters. Skyhook leverages existing Wi-Fi access points.
Five of the demonstrations were conducted at Joint Base Cape Cod, with the remainder at NASA’s Langley Research Center in Virginia.
Timing demonstrations were assessed for system:
coverage (service availability) within an “appropriate area” (wireless systems only)
accuracy and stability across an appropriate area
long-term accuracy and stability of time transfer to a fixed location
time transfer availability and accuracy to a fixed location under challenged GPS signal conditions.
Positioning was evaluated for:
coverage within a defined region
2D and 3D dynamic positioning service availability and accuracy
availability and accuracy of static positioning
long-term availability and accuracy of static positioning
long-term availability and accuracy of static positioning under challenged GPS signal conditions
DHS work referenced
The report also mentions an earlier set of demonstrations done by the Department of Homeland Security (DHS).
In December 2018, DHS’s Science and Technology Directorate performed the work through the Homeland Security Systems Engineering and Development Institute. The project “demonstrated a combination of position and timing use cases for dynamic vs. static and indoor vs. outdoor applications, along with a time-transfer use case for critical infrastructure applications.” Systems from Locata Corp, NextNav, and Satelles were evaluated.
The DoT report says that eLoran was not part of the DHS effort because of the lack of transmitters in the area. However, “DHS had previously studied eLoran performance under a Cooperative Research and Development Agreement (CRADA) with Harris Corporation and UrsaNav and had an understanding of its capabilities.”
A report of DHS’ December 2018 work is not publicly available, though DOT says it was used to inform their efforts.
The 437-page DOT report is filled to the brim with detailed information about the project, individual technologies, and demonstration results.
The Executive Summary says that, in addition to the findings from the DHS December 2018 effort (which were not listed), the DOT demonstration had four key findings:
All TRL-qualified vendors offered showed PNT “performance of value” and one showed value in all scenarios.
Neither eLoran company succeeded in the Static Basement Timing scenario.
R-mode ranging did not meet the minimum technical readiness level (TRL) of 6.
Deployment effort and coverage (infrastructure per unit area) are significant cost factors.
Addressing the needs of critical infrastructure owners and operators, the report concluded the needed “technologies are LF and UHF terrestrial and L-band satellite broadcasts for PNT functions with supporting fiber optic time services to transmitters/control segments.”
Reactions and way forward
Government officials and industry observers alike have welcomed the report, though it does leave some questions on the table.
One is about other national PNT needs. The congressional tasking was to report on GPS backup technologies for critical infrastructure and national security. The Jan. 14 report focuses on critical infrastructure needs. Information on national security requirements, some of which is classified, was provided to Congress separately by DHS and the Department of Defense.
“Economic and homeland security are sometimes considered by agencies and Congress as subsets of national security, sometimes not,” according to one analyst. “So, we don’t know if the needs of first responders, delivery services, civil government agencies, and other essential users were ever formally considered. The good news is that the combination of systems identified, if implemented and made available to all, would likely meet the needs of most.”
Other open issues are about implementing the report’s recommendations.
Some have been quick to point out that the demonstrations were to inform the government, not part of a procurement.
“If this was for an acquisition, it would have been done differently,” said one government retiree. “Rather than having vendors set up and operate the equipment, government evaluators would have been much more hands on. And they would have made every effort to do all the trials at the same location.”
Going forward, cost will also an important factor, as mentioned in the report’s key findings. “Depending on who you want to serve and where, the costs of different technologies vary by orders of magnitude,” said one provider.
Reaction from those involved with the demonstration project has been generally upbeat with praise for DOT’s effort and anticipation of more progress.
Typical were comments from Ganesh Pattabiraman, CEO at NextNav, who appreciated the real-world scenarios DOT used in the project. Regarding next steps he said, “We look forward to working with Congress on implementing the report’s recommendations.”
NASA’s Space Communications and Navigation (SCaN) program is developing capabilities that will allow missions at high altitudes to take advantage of GNSS signals for timing and navigation, including the Artemis missions to the Moon.
Interoperability of the GNSS constellations will be key for spacecraft at higher altitudes where GNSS signals are less plentiful. The program will rely on the four global constellations (GPS, Galileo, GLONASS and BeiDou) and the two regional systems operated by India and Japan.
SCaN is supporting flight experiments that will help develop multi-GNSS capabilities for spacecraft, such as Bobcat-1, developed by NASA’s Glenn Research Center in Cleveland and Ohio University.
Bobcat on the Prowl
Bobcat-1, shown with its deployable antenna stowed, will experiment with the GNSS inter-constellation time offset from low-Earth orbit. (Photo: NASA)
Bobcat-1 was selected by the CubeSat Launch Initiative in 2018 to study GNSS signals from 250 miles overhead. The small satellite launched to the International Space Station aboard a Northrop Grumman Cygnus spacecraft on Oct. 2, 2020.
On Nov. 5, the space station released the CubeSat to begin its mission. The spacecraft will orbit for about nine months, measuring signals from different GNSS constellations. Engineers will use these measurements to better understand GNSS performance, specifically focusing on timekeeping variations between the constellations.
“GNSS users at high altitudes see fewer satellites,” said Bobcat Co-Principal Investigator Frank Van Grass of Ohio University. “Time offsets between the constellations can be measured by the CubeSat and provided to these users to improve their positioning performance,”
SCaN Testbed
Bobcat-1 builds on the legacy of the SCaN Testbed, which demonstrated multi-GNSS capabilities on the space station from 2012 to 2019. The GPS and Galileo Receiver for the International Space Station (GARISS) — an instrument developed in collaboration between NASA and ESA (European Space Agency) — received signals from both GPS and Galileo, the GNSS constellation operated by the European Union.
The SCaN Testbed prior to launch to the International Space Station. (Photo: NASA)
The SCaN TestBed also laid the foundation for the Lunar GNSS Receiver Experiment (LuGRE), a Commercial Lunar Payload Services payload being developed in partnership with the Italian Space Agency. The payload will receive signals from both GPS and Galileo and is expected to obtain the first-ever GNSS fix on the lunar surface.
GNSS PNT Policy and Advocacy
While NASA engineers develop the technologies necessary for multi-GNSS navigation at ever-higher altitudes, the SCaN team works with stakeholders in the U.S. government and internationally to advance GNSS interoperability in the policy sphere. They consult on the United Nations International Committee on GNSS, helping develop additional capabilities in the Space Service Volume and beyond.
NASA recently worked to publish GPS antenna patterns from GPS satellites that launched between 1997 and 2000, collaborating with the U.S. Space Force, the U.S. Coast Guard and Lockheed Martin, who built the satellites. The PNT team is also working to facilitate publication of antenna patterns for more recent GPS satellites.
With this data, mission planners can better assess the performance of GNSS in high-Earth orbit and lunar space. This forthrightness also encourages other GNSS providers to be similarly transparent.
The Goddard PNT policy team received a 2019 Agency Honor Award for their advocacy of NASA’s interests in GNSS. From let are Frank Bauer, Jenny Donaldson, J.J. Miller, Ben Ashman and Joel Parker. Not pictured, Lauren Schlenker. (Photo: NASA)
“GNSS capabilities continue to revolutionize the ways spacecraft navigate in near-Earth space and beyond,” said NASA navigation engineer Joel Parker. “NASA’s longstanding relationships with the GNSS providers have advanced these capabilities to new heights and support the Artemis missions on and around the Moon.”
As in January 2020, we are starting the year by providing insights from manufacturers of GNSS receivers. We asked these industry leaders to look back at the past two years and forward at the next two, and discuss key innovations in the following areas:
utilizing Galileo and BeiDou
dealing with jamming and spoofing
integration with inertial measurement units (IMUs) and other sensors
positioning using cell phones and other consumer devices
any other areas or challenges they find particularly significant
Photo: Emma Hardy/Eos Positioning Systems
The single most important trend that emerges from manufacturers’ responses is the improvement in receiver performance due to the increase in the number of satellites (now 150) and signals (now more than 100). With four usable constellations, GNSS is now a reality. Multi-constellation receivers are quickly becoming the norm, even in consumer devices, and new user segments are benefiting from satellite-based PNT. Already, some smartphones and tablets are achieving decimeter-level or even centimeter-level accuracy. Over the next two years, new GNSS services will become available and, as the GNSS constellations continue to develop, the availability, reliability and repeatability of their signals will improve further.
A second important trend is the growth in satellite-delivered correction data, which substantially lowers the entry barrier for high accuracy applications by obviating the need for costly local infrastructure. This is starting to change the traditional cost-benefit calculation regarding real-time kinematic (RTK) vs. precise point positioning (PPP) corrections (see also our Editorial Advisory Board PNT Q&A).
A third and continuing trend is the increasing threat from intentional and unintentional jamming and interference across the globe, paralleling the increasing ubiquity of GNSS and potentially impacting most users. Therefore, receiver manufacturers continue to improve hardware and software techniques to defeat, or at least mitigate, this threat, greatly assisted by the increase in the number of available signals.
Finally, as automakers and high technology companies continue their efforts to develop autonomous vehicles (aka “self-driving cars”), the concept of GNSS integrity is getting renewed attention. Here, too, the increase in the number of available signals is extremely helpful.
With François Martin, Vice General Manager, International Division
Utilizing Galileo and BeiDou
The addition of Galileo and BeiDou to GPS and GLONASS not only extends GNSS positioning to more obstructed environments, but also allows the use of new survey methods, such as the hybrid IMU-GNSS pole-tilt compensated surveying and stakeout with survey-grade accuracy. Further expansion of GNSS navigation systems will result in even greater availability, reliability and repeatability.
Dealing with jamming and spoofing
As an integrator and developer of GNSS systems, we focus our design on strong electromagnetic shielding and sealed isolation chambers. From a technology standpoint, the combination of advanced GNSS signal processing, optimized antenna design, and advanced filtering ensures minimal interference.
Photo: CHC Navigation
Integration with IMUs and other sensors
The integration of interference-free, high-dynamic IMU fused with GNSS technology brings an obvious benefit to surveying and autonomous navigation applications. The latest algorithm developments make it possible to get rid of tedious initialization processes, increase the productivity of typical survey tasks, bring extra safety to operators, and compensate for transient GNSS outages.
Positioning with consumer devices
Multi-constellation GNSS chips are accelerating the development of untapped user segments, but the repeatability of position accuracy remains an issue. The integration of high-performance GNSS chips and helical antennas as high-precision add-on modules on smartphones and tablets enables centimeter- or decimeter-level accuracy. This democratization of technology is increasing earlier adoption of GNSS technologies by a broader user base.
Eos Positioning Systems
With Jean-Yves Lauture, Chief Technology Officer
Utilizing Galileo and BeiDou
The past two years have seen considerable maturation of the Galileo and BeiDou constellations. Considering the now four usable GNSS constellations and the aggressive launches of Galileo and BeiDou, the number of available satellites and the list of frequencies they use have considerably increased. Accuracy itself is slightly improving with the availability of BeiDou phase 3 signals, whereas performance and productivity experience a significant boost under tougher conditions with more satellites and stronger signal availability. It is not uncommon for our customers to use 30 to 35 satellites out of 40+ in view using an Arrow Series GNSS receiver. We are waiting for the availability of the High Accuracy Service (HAS) (PPP) on the Galileo E6 frequency, hopefully in a couple of years.
Photo: Eos Positioning Systems
Integration with IMUs and other sensors
Eos has put a lot of effort recently in supporting external sensors and accessories to facilitate mapping of certain types of assets or mapping in certain types of conditions. For instance, this past year Eos released our underground mapping solution called Eos Locate for ArcGIS (see cover photo), which integrates with external utility locate devices to allow a user to precisely map buried assets. Eos Laser for ArcGIS interfaces with laser rangefinders to map assets in GNSS-impaired environments.
Positioning using consumer devices
With our bring-your-own-device (BYOD) approach on the market to support high-accuracy data collection for GIS, we have made it possible to override the consumer devices’ locations with accuracies down to the centimeter from our Arrow receivers. Customers can use any of their cell phones or tablets and immediately start mapping with submeter or centimeter accuracy.
Hemisphere GNSS
With Kirk Burnell, Senior Product Manager
Utilizing Galileo and BeiDou
The Galileo and BeiDou phase 3 systems introduce modern signal structures that allow more accurate measurements to be made than GPS first introduced. The new signals and increased satellite count are significantly improving receiver performance. Our Phantom and Vega product lines harness these new signals.
Dealing with jamming and spoofing
The increasing number of incidents of intentional and unintentional jamming and interference across the globe has impacted nearly every type of GNSS user. Our Cygnus interference mitigation technology automatically detects and mitigates the interference in real time, as well as providing spectrum analysis of the GNSS signal bands.
Photo: Hemisphere GNSS
Integration with IMUs and other sensors
Today’s autonomous-focused environment increases the need to share data across platforms. Both Vector and Vega provide robust GNSS heading, position and velocity to marine, machine control, UAV and internet of things (IoT) integrators, helping augment their sensor data.
Positioning with consumer devices
Positioning in consumer products will continue to drive innovation, while chasing accuracy and precision requires a strong understanding of geodesy fundamentals. As design requirements push well beyond the limits of what consumer GNSS delivers, and with the help of our knowledgeable staff, our precision receivers are delivering reliable performance in some very impressive applications.
Other significant challenges and opportunities
New GNSS signals and new surrounding technologies continue to come online, and the RF environment continues to see increased activities. Our underlying Lyra II ASIC technology and Cygnus enable our Phantom and Vega integrators and users to reliably coexist with these changes.
Hexagon | Novatel
With Sandy Kennedy, Vice President Innovation, Hexagon’s Autonomy & Positioning division
Utilizing Galileo and BeiDou
GNSS is now reality, not just inclusive phrasing to replace GPS. We are well into the era of multi-constellation receivers, and users will notice distinct improvements in solution availability with the addition of Galileo and BeiDou measurements. Over the next two years, we expect users in a variety of applications to start exploiting our globally available, fast-converging RTK From the Sky technology, which is enabled by the addition of quad-frequency signals supplied by Galileo and BeiDou (see page 29).
Dealing with jamming and spoofing
The RF spectrum is crowded and will only become more crowded over time. In 2020, we introduced our GNSS Resilience and Integrity Technology (GRIT), a suite of firmware options for the OEM7 receiver family. In addition to interference detection and mitigation, GRIT adds spoofing detection and time-tagged digitized samples for advanced situational awareness of the RF spectrum. With GRIT’s spoofing detection, opponents can try to spoof us. But fool us? Not a chance.
Photo: Hexagon | NovAtel
Integration with IMUs and other sensors
IMUs have become more accessible to more applications due to size, weight, power and cost reductions. At the same time, our algorithmic capability has significantly advanced to use lower quality inertial measurements for greater benefit. Originally reserved for truth systems, high-end mapping, and aerospace and defense applications, GNSS+INS solutions are now available in products like our SMART7 line of smart antennas for precision agriculture applications. Closer integration of the inertial and GNSS processing will bring further benefits in hostile RF or just plain difficult positioning environments. There is no perfect single sensor, but you can get more accurate by combining a set of sensors that offset each other’s vulnerabilities and limitations.
Positioning with consumer devices
The general population is accustomed to looking at their smartphone to see not only their location, but also the size of the “blue dot” of positioning uncertainty that accompanies it. We have always said accuracy is addictive, and we will no doubt start to see consumer demands for smaller blue dots with increasingly accurate positions. Making the digital reality match our real world demands continuously available and reliable positioning. Being lost is a terrifying feeling, especially for those who have been staring at their phone for the past 30 minutes and have no recollection of the physical world through which they have passed.
Other challenges and opportunities
The transition to autonomous vehicles, for both on-road consumer and off-road industrial applications, is inevitable. It is becoming increasingly necessary to prioritize the development of functional safety and integrity requirements to achieve the safe operations of autonomous systems. These requirements are necessary and entirely non-trivial to develop.
Photo: Stephen Drake
Javad GNSS
With the Javad GNSS Team
Utilizing Galileo and BeiDou
Simultaneous RTK and PPK processing of all available GPS, GLONASS, Galileo and BeiDou signals in receivers powered by our 874-channel TRIUMPH chip has resulted in significant productivity gains. User Darren Clemons told us “These Plus units are at least 40%–50% faster… The combination of the four super engines and the RTPK is unbeatable. You can get an accurate shot just about anywhere.”
Dealing with jamming and spoofing
Usually, more than 100 signals are available at any given time, and we need only a small number to compute a position. By tracking and verifying all these constellations and their signals, it is extremely unlikely that we can be spoofed without our knowledge. Javad GNSS receivers will immediately recognize spoofing and take corrective actions. Spoofing protection is available on all Javad GNSS receivers and OEM boards.
Integration with IMUs and other sensors
The Javad GNSS engineering team relentlessly works to identify and integrate the latest sensor technologies that can boost productivity. Our TRIUMPH-LS’s integrated camera sensor has for years supported onboard photogrammetry, and now our TRIUMPH-3 receiver’s integrated IMU provides high-precision tilt compensation.
Other challenges and opportunities
Our innovative RTPK feature is improving GNSS surveying and monitoring. Our Triumph-LS and Triumph-3 RTK rover systems combine the strengths of RTK and PPK into a system that can post-process RTK data and verify its results in parallel and real time. Users get the best of both worlds. If RTK fails, RTPK comes to the rescue in a fraction of a second.
Septentrio
With Gustavo Lopez (pictured) and Stef van der Loo, Market Access Managers
Utilizing Galileo and BeiDou [GL]
With 150 GNSS satellites in space, multi-constellation has been a natural transition for improved GNSS availability. We see this in rover applications and in upgraded reference networks modernizing correction services. The next two years will be transcendent as constellations finally start delivering new services. We see our products soon integrating
GAL-OSNMA for anti-spoofing and then moving to new high-accuracy services.
Dealing with jamming and spoofing [GL]
We have witnessed a large increase in jamming and spoofing events as GNSS ubiquity increases. Users are becoming conscious of this, yet many integrations are still using vulnerable receivers, and we see manufacturers falsely claiming to have proper resilience. Septentrio’s AIM+ technology uniquely mitigates all these risks, and users come to us for expert advice on this area. In the coming years, we expect further receiver innovations and developments in adjacent technologies.
In 2020, Septentrio opened an R&D center in Espoo, Finland. (Photo: izhairguns/iStock/Getty Images Plus/Getty Images)
Integration with IMUs and other sensors [SVL]
Integration of sensors and sensor fusion moved from the research stage to the major production and adoption phase as an element in autonomous systems. Using a GNSS/INS (see our AsteRx-i products) is crucial for various applications — for example, being able to work in difficult environments — and for vehicle orientation. The development of lower cost IMUs while keeping high performance will enable a shift in focus from hardware to software. This will result in multi-sensor technology that is better scalable, easier to use, and more stable to integrate in relation to a full system with various sensors.
Positioning with consumer devices [GL]
We see further integration of dual-frequency GNSS chipsets in mobile technology for increased accuracy, which is key for future consumer applications. Septentrio has also witnessed the important involvement of telecom operators in GNSS correction services. Septentrio products (such as the PolaRx5 or AsteRx-SB) are deployed on new generation networks as operators prepare for the new generation of positioning in cell technology.
Other significant challenges and opportunities [GL]
Two areas are emerging thanks to the autonomy era and due to further regulations in the market. The first is the concept of GNSS integrity, which has a strong link to the reliability of autonomous solutions. The second is security, which, beyond anti-spoofing, is linked to the cybersecurity of GNSS systems as the demand increases for the protection of electronics and software.
Trimble
With Stuart Riley, Vice President of GNSS Technology
Utilizing Galileo and BeiDou
Most Trimble precision receivers can utilize any combination of GNSS satellite constellations (GPS, GLONASS, Galileo, BeiDou and QZSS) to deliver centimeter accuracy and optimize performance, even in degraded conditions. Users can select the constellations they want the receiver to use.
Dealing with jamming and spoofing
Spoofing is rare and low risk in locations in which Trimble’s precision GNSS agriculture, construction and geospatial customers operate. However, to protect users, modern Trimble Maxwell-based GNSS receivers implement hardware- and software-based techniques to detect and mitigate spoofing. Jamming sometimes impacts customers, but is not their primary challenge. The same issues are still present today as they were in the early days of precision GNSS. The main productivity concerns remain related to multipath and problems around obstructions and trees. Trimble continues to improve our GNSS systems’ robustness with advances in processing algorithms and hardware enhancements such as integrating inertial technology.
Trimble SiteVision uses Catalyst and augmented reality to preview a new housing development in an open field. (Photo: Trimble)
Integration with IMUs and other sensors
The Trimble R12i and SPS986 represent Trimble’s third-generation receivers (preceded by the R10 and the R12) capable of integrating inertial measurements into 3D GNSS positioning. In addition to speed and convenience for the user, integration with IMU provides immunity to magnetic interference and real-time integrity monitoring.
With the introduction of the Trimble R12 with the ProPoint GNSS positioning engine, we significantly improved the performance in challenging environments. This was further enhanced with the addition of an IMU for tilt compensation in the R12i. The new solution provides a system that delivers more accurate results in more places and in less time.
Positioning with consumer devices
The Trimble SiteVision augmented reality solution and Trimble Catalyst GNSS receiver operate on Android devices. Trimble Catalyst technology provides a software-defined GNSS receiver capable of survey-grade accuracy. Catalyst is the ideal solution for third-party applications that benefit from precise real-time positioning. Trimble SiteVision combines Catalyst positioning with augmented reality to deliver real-time, on-site visualization of proposed structures and existing underground assets.
Other significant challenges and opportunities
An ongoing challenge in GNSS positioning is the ability to obtain positions with suitable accuracy when and where they are needed. Solutions such as RTK and VRS provide solid performance at local and regional levels. Today, these technologies are complemented by subscription-based Trimble RTX positioning services, a global approach that uses a network of GNSS tracking stations and satellite-delivered correction data to achieve required accuracies. In 2020, coverage for Trimble CenterPoint RTX Fast, which enables users to achieve two-centimeter or better accuracy with initialization time of less than one minute, was expanded to cover the continental United States as well as much of Canada and Western Europe. The CenterPoint RTX Fast network now covers more than 5 million square miles worldwide. Trimble RTX coverage enables global users such as farmers, land surveyors and GIS professionals using RTX-capable receivers, to untether from the cost and complexities of GNSS base stations. In addition, the service offers a single, continuous corrections network ideal for enabling a broad range of safety-critical autonomous applications in markets such as automotive, agriculture and construction.
Schematic of the GNSS interference detection and analysis system GIDAS. (Image: OHB Digital Solutions)
In September 2020, the first GIDAS monitoring stations were installed at the Czech airport in Brno.
GIDAS — GNSS Interference Detection and Analysis System — enables continuous 24/7 monitoring of the GNSS frequency bands within a defined region to automatically detect, classify and localize intentional interference from jamming and spoofing.
GIDAS can raise the alarm in real time, identify the type of interference, and then pinpoint the location of these dangerous portable devices causing the interference so the authorities can take immediate remedial action. It considerably improves safe and robust operation of GNSS receivers, terminals and applications.
GIDAS was developed by OHB Digital Solutions and Joanneum University of Applied Sciences through ESA’s Navigation Innovation and Support Programme (NAVISP).
The system works autonomously and is designed to be easily deployed. It is scalable and flexible; it can be used as a standalone monitoring station or upgraded to a network of stations.
Recent GNSS interference attacks include:
shutdown of navigation equipment at Newark airport
GNSS attacks of North Korea against South Korea
117 incidents within one day at Kaohsiung airport in Taiwan
a U.S. military drone forced to land
a 65-meter yacht drifting off course during field trials
failure of emergency pagers, traffic management systems and ATMs in San Diego caused by U.S. Navy jamming.
“In recent years, GNSS applications have increasingly become the target of intentional interference attacks, since GNSS is widely used in safety and value-critical applications,” said Andreas Lesch, CEO of OHB Digital Solutions. “GIDAS detects, classifies and localizes GNSS interference signals and thus reduces the already existing threat of receiving worse accuracies or even denial of service.”
The GIDAS system user interface helps to pinpoint interference. (Image: OHB Digital Solutions)
GIDAS monitors the GNSS L1/E1 frequency band and reliably detects and classifies intentional and unintentional interference sources using sophisticated algorithms. GIDAS consists of a high performance data processing unit including antenna and RF front-end, and a sophisticated software solution.
GIDAS is able not only to monitor GNSS-based position, velocity and time solutions, it monitors the received signal and baseband processing.
The system is composed of the following software modules:
Software-defined GNSS radio
Position, baseband and C/N0 monitoring
Jammer and spoofing parameter estimation
Localization capabilities through synchronization of several GIDAS systems
Graphical user interface
Initial GIDAS reports show an average of seven GNSS interference events per day. GIDAS was able to successfully classify the signal type in 96% of jamming cases that have occurred.
The end of 2020 marked a milestone for the Galileo First Generation, as the program chalked up its 500th European Space Agency (ESA) Engineering Board.
For more than 12 years, ESA and industry engineers from all relevant disciplines — system, satellite, ground, signal, radio navigation, RAMS (reliability, availability, maintainability and safety), security and infrastructure — have put their best skills at the disposal of the board.
The board is a forum where technical experts regularly meet to maintain, review and update the Galileo Project technical baseline, known as the System Technical Requirements Baseline (STRB). The STRB drives the implementation of the Galileo System and its infrastructure, the space and ground segments, along with associated interfaces and operations.
The G1 system technical specification under ESA adds up to more than 22,000 separate requirements. These requirements are both unclassified and classified, with considerable interdependencies which all that need to be controlled in configuration.
The Galileo G1 Engineering Board is chaired by ESA in accordance with its role as Galileo System Design Authority, assigned to it by the European Commission.
Since the building of the first G1 Engineering Board in 2008, 26 Galileo satellites have been built, tested and flown. The Galileo system’s globe-spanning ground system has also been put in place and made operational. The board continues to be a crucial enabler for further robustness improvements and new service evolutions.
A further 12 Batch 3 satellites are set to join the constellation in the coming decade. These satellites are being finalized at OHB Systems in Bremen, Germany, and then tested at ESA’s ESTEC Test Centre in the Netherlands.
The worldwide Galileo ground segment includes two control centers (Italy and Germany) as well as various tracking, uplink and sensor stations and monitoring and test centers. (Image: ESA)
Galileo began initial operations in December 2016 and today serves more than 1.5 billion smartphones and devices.
The G1 Engineering Board meetings will continue, complemented with Engineering Boards for the new Galileo Second Generation (G2 satellites are planned for later this decade), which are already well underway.
Lockheed Martin Space has released the GPS-III satellite antenna phase-center data, as well as the group delay and inter-signal correction data, for SVN-76 and SVN-77 as measured at the factory, announced the U.S. Coast Guard’s Civil GPS Service Interface Committee (CGSIC).
The phase center and inter-signal bias data included in this new release provide additional information that supplements the antenna gain pattern data previously available.
Note that the GPS III satellite vehicles (SVNs) also broadcast the Inter-Signal Corrections (ISCs) in the various LNAV/CNAV messages in accordance with all the external IS/ICDs. The value that is being broadcast by the on-orbit constellation is not the factory measured ISCs but the ISCs estimated on-orbit by the Stanford Research Institute (SRI).
As we embark on a new year, 2021 ushers in a new administration and the start of the 117th Congress. With these changes comes a litany of opportunities, as well as challenges, for the nearly four-decade-old GPS industry.
Next month, the GPS Innovation Alliance (GPSIA) will mark its eighth anniversary as the voice of the GPS industry, educating policymakers and regulators about the GPS success story of innovation, economic growth and job creation. It is a uniquely American story made possible because of bipartisan support for protecting the spectrum used by GPS and maintaining funding to enable the modernization of the GPS constellation, ground control and military ground user equipment.
Congressional Support. This commitment was evident in the last Congress through broad support from both parties for two Congressional resolutions, H.Res.219 and S.Res.216, that affirmed the importance of continuous availability, accuracy, efficiency, robustness, reliability and resiliency of the GPS constellation.
Innovation and modernization of the GPS constellation are well underway. Last year, under the emerging leadership of the U.S. Space Force, two new Lockheed Martin-built GPS III satellites were launched into space. This new generation of GPS satellites offers three times greater accuracy, up to eight times improved anti-jamming capability for military users, and the addition of the L1C signal to enable interoperability with other navigation systems, such as Europe’s Galileo.
GPS modernization also has led to the introduction of M-code, an advanced, new signal designed to improve anti-jamming and anti-spoofing, as well as to increase secure access to military GPS signals for U.S. and allied armed forces. In GPS-denied environments, M-code reduces the jamming radius, giving military planners and targeteers options to minimize or avoid collateral strike damage.
With at least two additional GPS III satellites set to launch this year and a new ground control segment known as the Next Generation Operational Control System (OCX), the continued success of the GPS program remains bright.
Ligado Still Looms
As GPSIA continues to urge Congress to allocate the funding needed to support the modernization of GPS, we also are fighting to ensure uninterrupted operation of the estimated 900 million GPS devices in the United States ranging from precision agriculture to consumer gadgets.
Last year, we were deeply disappointed by the Federal Communications Commission’s (FCC) decision approving the applications of Ligado Networks, despite the well-documented objections of the expert agencies charged with preserving the integrity of GPS, specifically, on the critical issue of what constitutes harmful interference to users of GNSS.
Regrettably, the FCC chose to ignore the established “1-dB Standard,” which has a long history of protecting GPS operations from harmful interference in both international and domestic regulatory proceedings.
“All Americans benefit from a competitive 5G landscape.”
At the same time, Ligado and its supporters continue to argue that their proposal is the fastest way to bring 5G to all Americans. In actuality, millions of Americans already have access to 5G services and, thanks to the efforts of the FCC, hundreds of megahertz of 5G spectrum in low-, mid- and high-band frequencies have been or will soon be made available for commercial use. GPSIA believes all Americans benefit from a competitive 5G landscape.
5G without compromise. However, that goal can be achieved without undermining GPS receivers and devices that are foundational to wireless technology in general, including 5G. We remain hopeful that a new administration and congress will commit to protecting GPS receivers from harmful interference using the appropriate standard for determining such interference to ensure that the more than $1 billion per day in U.S. economic impact created by GPS continues to flourish.
2020 also brought the issue of GPS resiliency into the national forefront. In February, the president signed an Executive Order aimed at fostering greater resiliency for positioning, navigation and timing (PNT)-based systems, including GPS.
GPSIA supported this order and outlined in subsequent regulatory filings why GPS remains the gold standard for delivering PNT functions to our military as well as a wide range of other sectors, including transportation, agriculture, electricity and finance.
Complementing GPS. As the federal government considers alternative PNT solutions, it is critical that they be complementary to GPS, able to easily integrate into current or future devices, and based on a recognition that each PNT application has unique requirements driven by its intended function, environment and design factors. In sum, there is no one-size-fits-all solution.
Protecting Consumer Privacy. Looking ahead, GPSIA expects 2021 will bring a robust discussion around consumer privacy protections. While GPS satellite broadcasts are one-directional and cannot track a user’s location, we recognize that GPS is one of many data points that can contribute to application-specific location tracking. As such, GPSIA would urge Congress to ensure that geolocation data is appropriately addressed as part of any U.S. federal privacy legislation. In doing so, we believe protections for precise geolocation information will empower consumer choice, enhance transparency, and strengthen security.
On the surface, infrastructure modernization, protecting GPS spectrum, PNT resiliency, and consumer privacy may seem like distinctly different issues. What they have in common, though, is an ability to garner bipartisan support, deliver substantial consumer benefits, and strengthen our nation’s economy. GPSIA stands ready as a resource and looks forward to working with the Biden-Harris Administration and leaders in the House and Senate to promote, protect and enhance GPS.
