What is the most promising approach to increasing the location accuracy of smartphones?
Ismael Colomina
“In addition to the use of increasingly available augmentation services, such as Galileo’s free High-Accuracy Service (HAS), I see two development directions that may help, particularly in the context of positioning in urban areas where smartphones are most used. One is the use of 3D city models — in general, 3D geoinformation — to compensate for multipath, non-line-of-sight and occlusion effects. The other is to use signals that are robust against those effects, which today are only available in geodetic-grade receivers.” — Ismael Colomina, GeoNumerics
For the navigation of autonomous vehicles, will GNSS become essential, or will it be relegated to a secondary role by robotic navigation methods?
John Fischer
“The PNT solution cannot be from a single source because autonomous navigation requires high integrity. Therefore, it’s not that GNSS will be relegated to secondary status, it’s that no one method will be primary. An intelligent fusion of diverse sensors —including GNSS — will provide the PNT solution along with an integrity metric that safeguards operation. The various sensors must agree. If they don’t, no trust can be put into the solution and autonomous navigation will cease. The definition of a new integrity metric that quantifies this trust level is needed.” — John Fischer, Orolia
Ellen Hall
“Because GNSS provides high precision and widely available PNT, it will continue to be a critical component in navigation while working with computer vision, inertial measurement units (IMUs) and lidar through sensor fusion. As a secondary component, GNSS serves a vital role for localization and validation.” — Ellen Hall, Spirent Federal Systems
Given that space is increasingly a congested and contested arena, should the U.S. government establish a new office to manage both space-based and terrestrial-based PNT systems?
John Fischer
“The U.S. government already has the National Executive Committee for Space-Based PNT (see gps.gov), which coordinates policy among all the branches of government. There is also a PNT Advisory Board, which includes some international members to inform the committee, and a National Coordination Office to execute the policies. This is in addition to the new U.S. military’s Space Command under which GPS operates. So, space-based issues are being addressed, but maybe more could be done to coordinate terrestrial-based PNT systems with space-based ones.” — John Fischer
Ellen Hall
“As new technology advances, government, along with its policies and laws, struggles to keep pace. This was certainly true of the internet and cybercrime. This is also true of terrestrial-based PNT, where new technology emerges in areas not currently covered. Policy gaps and overlapping technologies need to be addressed and coordinated. It certainly seems that this would be one of those areas that could benefit from oversight. Space-based PNT is currently addressed by the National Executive Committee for Space-Based PNT, among others.” — Ellen Hall
Bernard Gruber
“The threat to U.S. space-borne assets and the signals they generate is very real. Both commercial and military users of GPS continue to seek independent alternatives to current PNT systems that are diverse and robust. The National Coordination Office supports the National Executive Committee (NEC) for Space-Based PNT. I believe the role of the NEC should be broadened to include terrestrial and alternative PNT as a first step to charter/secure a new or expanded program office.” — Bernard Gruber
Editorial Advisory Board
Tony Agresta, Nearmap
Miguel Amor, Hexagon Positioning Intelligence
Thibault Bonnevie, SBG Systems
Alison Brown, NAVSYS Corporation
Ismael Colomina, GeoNumerics
Clem Driscoll, C.J. Driscoll & Associates
John Fischer, Orolia
Bernard Gruber, Northrop Grumman
Ellen Hall, Spirent Federal Systems
Jules McNeff, Overlook Systems Technologies
Terry Moore, University of Nottingham
Mitch Narins, Consultant
Bradford W. Parkinson, Stanford Center for Position, Navigation and Time
The Institute of Navigation (ION) presented its annual awards during the ION International Technical Meeting (ION ITM) and Precise Time and Time Interval Systems and Applications (PTTI) meeting held Jan. 25-27 at the Hyatt Regency Long Beach in Long Beach, California.
The ION Annual Awards Program recognizes individuals making significant contributions or demonstrating outstanding performance relating to the art and science of navigation.
Jonathan “JR” Ryan received the Per Enge Early Achievement Award for developing vision-based navigation software used operationally on aircraft, UAVs and glide munitions that provides continuous high-accuracy absolute position measurements in GPS-denied environments. The Per Enge Early Achievement Award is presented in recognition of outstanding contributions made early in one’s career.
Major Matthew L. Sutton received the Superior Achievement Award for his ingenuity, dedication and leadership in ensuring critical operational test and tactics improvements for warfighters in a contested electromagnetic environment. The Superior Achievement Award is presented to recognize an individual who has demonstrated outstanding performance as a practicing navigator of any vehicle, in any medium — marine, land, air, undersea and space.
John Fischer received the Distinguished PTTI Service Award for his pioneering research, patents, and leadership that advanced resilient positioning, navigation, and timing technology; and his prominent role in increasing global awareness of PNT. The Distinguished PTTI Service Award is presented to recognize outstanding contributions related to the management of PTTI systems. Fischer is a member of the GPS World Editorial Advisory Board.
Mark L. Psiaki received the Dr. Samuel M. Burka Award for his paper “Navigation Using Carrier Doppler Shift from a LEO Constellation: TRANSIT on Steroids” published in the Fall 2021 issue of NAVIGATION: Journal of the Institute of Navigation, Vol. 68, No. 3, pp. 621-641. The Dr. Samuel M. Burka Award recognizes outstanding achievement in the preparation of a paper advancing the art and science of positioning, navigation and timing.
Satoshi Kogure received the Captain P. V. H. Weems Award for technical and programmatic leadership in the development of Japan’s Quasi-Zenith Satellite System serving the Asia-Pacific region, and for leadership in international GNSS. The Captain P. V. H. Weems Award is presented to individuals for continuing contributions to the art and science of navigation.
Dana A. Goward received the Norman P. Hays Award for inspirational leadership in the pursuit and preservation of navigational excellence, developing international support for protecting, toughening and augmenting GNSS, and for advocating policies and systems to support resilient PNT. The Norman P. Hays Award is given in recognition of outstanding encouragement, inspiration and support contributing to the advancement of navigation. Goward is a frequent contributor to GPS World magazine.
Ignacio Fernández-Hernández received the Thomas L. Thurlow Award for pioneering contributions in the design and development of GNSS authentication and high-accuracy services. The Thomas L. Thurlow Award recognizes outstanding contributions to the science of navigation.
Fellow Members Announced
ION also announced recipients of 2022 Fellow membership during the conference. Election to Fellow membership recognizes sustained professional accomplishments that have significantly contributed to the advancement of the arts and sciences of positioning, navigation and/or timing (PNT) in the areas of technology, management, practice or teaching and a demonstrated and sustained impact on the PNT community. Fellows have maintained an observable presence in the ION community over the long term, including contributions to ION programs and publications.
Dennis M. Akos was elected for fundamental contributions to the design, development and commercialization of GNSS software-defined radio technology.
Charles A. Schue, III, was elected for distinguished and sustained technical and strategic contributions, leadership and guidance in resilient PNT solutions.
Charles K. Toth was elected for significant contributions to the development and implementation of multi-sensor integrated navigation systems, and for demonstrated excellence as an academic mentor and professional leader.
The U.S. military is transitioning to M-code. When the transition is complete, what will become of the SAASM P(Y) code? What should be done with it? Should the U.S. government use it as a public authenticated service?
Jules McNeff
“In my opinion (not speaking on behalf of the Defense Department), eventual use of the P(Y) code as a public authenticated service is not feasible based on both time and accessibility. Even with the transition to M-code, the legacy P(Y) code will continue to be used by the U.S. military and by U.S. allies and partner nations as long as there are military requirements for it. More importantly, public access to the encrypted P(Y) code would require general distribution of classified cryptographic keys and associated hardware/software by the DOD. That will not happen, even if the P(Y) code use is discontinued.” Jules McNeff Overlook Systems Technologies
Bernard Gruber
“Broadly speaking, GPS user equipment security architectures transition every 10 years (such as PPS-SM/AOCs to SAASM to Modernized CGM/MSI.) It can be argued that implementation of these security measures generally takes 10 years or longer to implement. SAASM P(Y) receivers will be around for a long time, implementation can be expensive, backwards compatibility is critical. Personally, I would like to see SAASM architectures evolve to support critical services within other U.S. government departments first, and then determine a path that supports a public service as threats, unfortunately, move forward.” Bernard Gruber
Northrop Grumman
John Fischer
“Why not? Authentication protects against spoofing. I don’t know all the obstacles involved, but even if an internet connection is required to overcome the one-way limitation of GPS, that isn’t a problem for most applications. Our credit card transactions are secured this way, why not our PNT information? Decades ago, the U.S. Air Force gave the world a gift with the open GPS signal; they could do it again with a secure signal. The world would be a better place.” John Fischer
Orolia
F. Michael Swiek
“It’s premature to forecast when military operations will transition from P(Y) code even after M-code operations achieve Initial and Final Operating Capability (IOC and FOC). SAASM P(Y) code will continue to support military operations for an extended period since all MGUE receivers (both increments 1 and 2) are YMCA capable, meaning they support P(Y) code, M-code and C/A code operations. As a military-encrypted signal with military utility, military leaders must carefully weigh any potential P(Y) code transition and its impact on military operations.” Michael Swiek
GPS Alliance
Ellen Hall
“If P(Y) code is offered as a new service to the public, it will have to be maintained. This carries a great cost. This is a legacy product that had a specific military need, which has been replaced and improved upon by M-code. In today’s uncertain times, we need to be wise with our tax dollars. The cost to continue both SAASM and M-code is greater than the benefit to the public, in my opinion.” Ellen Hall Spirent Federal Systems
Feature photo: U.S. Marine Corps/Capt. Joshua Hays
Two decades ago, the Volpe National Transportation System Center released its landmark report on the vulnerability of GPS. Have this study and its many successors helped move us to the necessary levels of PNT resilience? Have we done enough? What is left to be done?
Bernard Gruber
“This study and others underscore that safety must be maintained in the event of GPS loss. Among the many recommendations, I maintain that ‘systems and procedures to monitor, report, and locate unintentional [and intentional] interference should be implemented.’ Similar to GPS integrity monitoring, awareness of signal vulnerability ‘hot spots’ may allow an understanding of the RF landscape, and thus users may employ tactics, tools and techniques to combat against it. This ‘issue’ will not be solved with a singular solution; rather, continued education and urgency will produce innovative solutions over time. I just hope that a large ‘trigger event’ is not needed to do so.” — Bernard Gruber, Northrop Grumman
John Fischer
“We have widespread awareness now, but not enough implementation of safeguards. There is no one simple solution – a single alternative system to GPS is not the answer. Rather, the integration of several diverse alternative PNT sources will provide the necessary resiliency. DHS and NIST have taken the proper initial steps to set standards for resiliency, but the next step is implementation. Twenty years without a major incident has only reinforced complacency, but we can’t keep betting our luck will continue. We have everything we need now — the technology, the standards, the exec orders — let’s implement!” — John Fischer, Orolia
Ellen Hall
“This study was instrumental in getting the U.S. government to face the fact that GPS is vulnerable on many fronts. It seems that the first response was to focus on making signals more robust and therefore less vulnerable. The backup systems, alternatives, or simply additional sensors have come onto the scene very slowly due to factors that include funding, politics, and difficulty in deployment on all platforms, where the costs could be astronomical. I hope that it doesn’t take a catastrophic event to force all factions to come together to find best solutions, but that is sadly often the case.” — Ellen Hall, Spirent Federal Systems
GPS World Editorial Advisory Board
Tony Agresta
Nearmap
Miguel Amor
Hexagon Positioning Intelligence
Thibault Bonnevie
SBG Systems
Alison Brown
NAVSYS Corporation
Ismael Colomina
GeoNumerics
Clem Driscoll
C.J. Driscoll & Associates
John Fischer
Orolia
Bernard Gruber
Northrop Grumman
Ellen Hall
Spirent Federal Systems
Jules McNeff
Overlook Systems Technologies
Terry Moore
University of Nottingham
Mitch Narins
Consultant
Bradford W. Parkinson
Stanford Center for Position,
Navigation and Time
As the number of GNSS constellations and satellites in orbit continues to grow,
will we reach the point of diminishing returns?
Ellen Hall
“More satellites equal more data, and redundant constellation systems — through GNSS interoperability — can give us more robust PNT, as restated in the January Memorandum on Space Policy Directive 7. That said, there are always diminishing returns. Treaties place liability on the launching country if something goes wrong, but with tens of thousands of small satellites expected to be launched over the next decade, it will be getting increasingly crowded. Concerns are growing about the necessity of increased maneuvers to keep these satellites from a chain reaction of collisions, which ultimately could cause debris to fall to inhabited areas of Earth.” — Ellen Hall / Spirent Federal Systems
Jean-Marie Sleewaegen
“With already more than 130 GNSS satellites in orbit, the benefit of new satellites decreases while the risk of satellites interfering with each other increases. However, this is only considering GNSS as we know it, in the MEO orbit (altitude about 22,000 km). The future of GNSS may well be closer to Earth, in the LEO orbit (<1,000 km), with well-known benefits in terms of convergence time and resilience to jamming. Sooner than later, we can expect constellations of hundreds or thousands of LEO satellites carrying a GNSS-like payload supporting PNT services. No worries, there is still growth potential!” — Jean-Marie Sleewaegen / Septentrio
Stuart Riley
“With the current four GNSS constellations and a typical survey elevation mask of 10˚in North America, we average around 30 visible satellites. Far more are visible in Asia with the addition of the regional systems. In an area with a clear view of the sky, this provides more than enough satellites for precision centimeter positioning. However, most professional GNSS users do not have the luxury of operating exclusively in open areas with ideal conditions. Accessing many satellites across multiple constellations increases the probability of receiving sufficient satellites that produce high-quality measurements in obstructed areas. As the constellations expand, we observe improvement in precision position availability in these locations. The large number of satellites, coupled with independence across the four systems, improves system integrity and continuity while also helping to reduce the converge time in PPP solutions.” — Stuart Riley / Trimble
Bernard Gruber
“In a utopian vision of navigation, data gluttons and like-users of GNSS would say that there will never be enough! If capabilities remained static, then yes, I believe we would reach the point of diminishing returns. I would offer that innovation and competition will continue to drive capability improvements via power, signal quality, coverage, integrity and clock/timing accuracy. These innovations, coupled with user equipment flexibility utilizing signals from space, will drive an ever-maturing market balance and increasing return.” — Bernard Gruber / Northrop Grumman
Are military tests that jam and spoof GPS signals a threat to the safety of civil aviation? If not, why? If so, who should do what about it?
Bernard Gruber
“I would offer that military tests that jam and spoof signals are a risk. The U.S. military takes great care to control tests of this nature in an informed and careful way in order not to affect civil aviation. I cannot speak for military tests that are conducted by other countries. We all recognize the worldwide proliferation of small and large jammers that can negatively affect GPS performance and satellite-born transmissions. Accordingly, GPS users should remain vigilant to these potential hazards, including spoofing, and consider alternative navigation means where risks dictate.” — Bernard Gruber
What are the remaining obstacles to creating a seamless indoor/outdoor positioning and navigation system that integrates data from GNSS, inertial guidance, indoor positioning systems, and signals of opportunity?
John Fischer
“The primary use case for indoor navigation is the smartphone. We can create multi-sensor navigation systems today that operate indoors, but not at the very small size, weight, power, and cost targets needed for the personal phone market. IMUs and processors continue to improve over time, so there may be a breakthrough there, but signals of opportunity (SoOP) navigation is promising and offers resiliency through diversity. The most ubiquitous SoOP is cellular and with ultra-reliable low latency (URLL) features coming on-line for 5G in the next few releases, we may see reliable positioning from 5G in indoor environments very soon.” — John Fischer
What should the new administration’s priorities be to make PNT more resilient?
We asked Brad Parkinson, the “Father of GPS” and a GPS World Editorial Advisory Board member, what the new U.S. administration’s priorities should be to make positioning, navigation and timing (PNT) more resilient. For more answers from board members, see below.
Brad Parkinson
Protect the Spectrum. Reverse FCC authorization for relatively high-powered Ligado transmitters that have been proven to degrade GPS and other GNSS operation for thousands of PNT users. All U.S. government departments and major user groups affected have pleaded with the FCC to reverse this terrible decision. There is little benefit from it to the American public.
Protect the rapidly evaporating and self-proclaimed Gold Standard of GPS. The GPS satellite designs are showing their age. They need to go to multiple launch (three at a time) and revert to simpler designs without the spot-beams and other weighty add-ons that greatly increase complexity and cost. The Chinese have added to BeiDou (a) inter-satellite precision ranging and wide-band communications, (b) geosynchronous satellites, probably with good spot-beam acquisition aids, and (c) a WAAS-like correction directly on the satellites, which may have accuracies down to real-time kinematic (RTK, perhaps a few centimeters). Also, they claim their basic accuracies to be better than GPS (it might be true!) — I think they already have operational retro-reflectors.
Allow and encourage export of the basic and quickest fix to jamming and spoofing for high-value PNT users. More than 40 years ago, we demonstrated, in hardware, a high anti-jamming receiver that could fly directly over a 10 kW GPS jammer and not be affected. We know that high-gain, digital beam-steering antennas will create close to immunity, but our manufacturers will not move this way because we cannot sell or use them on the international market.These devices, combined with inexpensive inertial components and the newer signals, would make PNT virtually immune to current threats of interference — both jamming and spoofing.
Move the military focus from alternative PNT techniques to seriously upgrading their receivers and useful signals. No current or reasonably anticipated alternative can provide the accuracy (3D), availability or integrity of GPS. The new M-code and L1C signals have been in the queue for about 20 years. (Loran for ground operations probably is very vulnerable to direct attack in a fluid battlefield operation. Loran’s main value is to distribute time and for maritime users.) In those 20 years, we now have cellphone chips costing less than $5 that can listen to about 200 ranging signals and process RTK, as well as use all the corrections available (WAAS, EGNOS, etc.). Such capability cannot be found in military receivers. The Defense Department must improve its acquisition strategy in terms of both speed and competition, and ncorporate existing civil capability into military user equipment.
Take government actions to rapidly identify, shut down, and prosecute GPS jammers. Some believe this problem is much larger than recognized already. All cellphones should be required to report extraordinary spectrum noise levels or apparent attempts at spoofing. This should be fed to a dynamic national database, perhaps maintained by the Coast Guard. GPS users should have an automated way to find out whether there are substantial threats in their operating area.
Brad Parkinson is the Edward Wells Professor, Emeritus, Aeronautics and Astronautics (recalled) and co-director of the Stanford Center for Position, Navigation and Time at Stanford University.
Editorial Advisory Board PNT Q&A
Here are additional responses to the question from more GPS World Editorial Advisory Board members.
John Fischer
“We hope the new administration continues on the path established with the Executive Order last year for resilient PNT, supporting progress made by DHS and NIST in establishing resilient and cybersecure frameworks. It will be important for them to maintain an open market concept toward future innovative solutions and not mandate a particular PNT approach. Awareness of the criticality for trusted PNT in our mobile connected society is established and we must not lose this.” John Fischer Orolia
Jules McNeff
“Resilient PNT should be a national security priority. Its continuity is vital to both military and economic/social activities of all kinds. Its qualities of spatial awareness and synchronization enable the efficient functioning of the most sophisticated modern technologies in the physical and cyber worlds while also simply getting people and things from point A to point B on schedule. In that context, the elements which comprise resilient PNT should be protected from natural or hostile disruption.” Jules McNeff Overlook Systems Technologies
Greg Turetzky
“Truly resilient PNT requires combining multiple positioning technologies to maximize resiliency. However, the government’s influence in many of the augmentation technologies (sensors, vision, etc.) is limited. What the administration can do is make GPS itself more resilient by speeding up the launch and acquisition schedule of GPS Block III. The new signals, particularly at L5, are invaluable for improved resiliency to jamming and spoofing as well as providing a significant improvement in accuracy.” Greg Turetzky Consultant
John Fischer, vice president, advanced R&D, Orolia
In 1990, I had just left the military electronics industry (radars, electronic warfare) and entered the growing wireless telecom industry. Recall, this was at the end of the Cold War with shrinking U.S. defense budgets. Alas, after eagerly waiting for the full operational performance of GPS throughout the 1980s, I unfortunately missed its early successes.
I spent the 1990s in startups, working to provide wireless alternatives to dial-up and leased lines. We founded Clearwire, which eventually became WiMax — the broadband wireless on-ramp to this new “information superhighway” we now call the internet.
However, within a few years, we started to look for a way to synchronize our adjacent basestations to avoid interference at overlapping regions. Those of us who came from the military navigation sector turned to GPS. We began to use a GPS receiver to give us a 1PPS sync.
This worked well, although we had to train our installers not to put the GPS antenna high up on the tower with all the others, but low, away from the transmission beams. It was hard for them to believe we got better reception on the ground than up high!
The Trimble Accutime 2000. (Photo: Trimble)
By the late 1990s, Trimble had introduced its Accutime 2000, which made our lives easier. (Everything futurist in those days was called Something-2000 — the new millennium was approaching). Today, it is the standard for time sync, but back then, it was novel.
When I think of the progress in terms of Moore’s Law (semiconductor performance doubles every 18 months), we have been through 20 doublings since 1990. That is an improvement factor of a million!
However, technological advancement alone does not account for GPS’ huge success. The fact that the U.S. military opened its system for use by everyone in the world, and the continued cooperation of all nations in making all GNSS systems interoperable, is mind blowing.
We are living in the world that John Lennon only “Imagine(d)”: all the people sharing. In 2020, we are now focused on GNSS vulnerabilities and protecting the integrity of GNSS signals, which are such an integral part of our daily lives. GPS is truly a modern miracle.
John Fischer, vice president of advanced R&D at Orolia, will join three industry leaders as a panelist in a National Institute of Standards and Technology (NIST) workshop about the federal government’s PNT Executive Order. Fischer is a member of GPS World’s Editorial Advisory Board.
Other workshop panelists include Michael Calabro, chief engineer at Booz Allen Hamilton; Michael J. Lewis, senior staff security strategist at Chevron; and Gerardo Trevino, technical leader in cyber security at the Electric Power Research Institute. The workshop will take place Sept. 15-16.
The PNT Executive Order requires the development of positioning, navigation and timing (PNT) profiles to ensure that the nation’s critical infrastructure is resilient to disruptions or denial of service attacks on GPS signals and PNT data, Orolia said.
NIST, the organization hosting the workshop, is working to provide a ybersecurity framework-based profile to promote the responsible use of PNT services and help critical infrastructure owners make risk-informed decisions to protect their systems.
NIST is also seeking feedback on the Cybersecurity Profile for the Responsible User of Positioning, Navigation, and Timing (PNT) Services Draft Annotated Outline, which can be viewed here.
Not just supporting players, alternative positioning, navigation and timing (PNT) systems strengthen, augment and — when needed — replace GNSS. GPS World explores how companies are using alternative PNT, and talks with John Fischer of Orolia about the company’s latest developments.
GPS World: What are Orolia’s latest advances and products regarding alternative PNT?
John Fischer: Regarding timing, which we have been doing for decades, our big alternatives to GNSS are internal atomic clocks and network-based timing, such as precision time protocol (PTP). Regarding positioning and navigation, the two areas on which we focus are IMUs and getting updates from GNSS, so that, when you lose GNSS momentarily, you have something on which to coast. The breakthroughs in MEMS technologies are astounding —they are getting better and cheaper every day. That shows wonderful promise.
The other area is doing satellite navigation using low Earth orbit (LEO) satellites, which are much closer to the Earth than GNSS ones and give you 30 dB or more of signal strength. We are focused the most on the Satellite Time and Location (STL) signal because it is available today. Supplementing your navigation system with updates from LEO satellites provides you some great non-GNSS navigation capability.
GPS World: The positions of LEO satellites are not monitored as closely as those of GPS satellites. Is that an issue?
JF: That is correct. You are losing accuracy by using what is available today because you do not know the positions of those satellites as well as you know those of the GNSS satellites and maybe you do not have the best geometry. All the GNSS satellites are in medium Earth orbit (MEO) because they have much better geometries for a small constellation. With just 24 satellites in MEO orbit, you get great geometries. When you go lower, you need an increasingly greater number of satellites.
The first generation of LEO satellites, the Iridium STL, are a much larger constellation, with 66 satellites, but still not enough to give you the good geometries. Today, you are getting less accuracy, but there are all kinds of new satellites being launched and the capability to track them will improve. We expect to be able to use signals from hundreds, if not thousands, of LEO satellites, so the geometry problem will start to go away and there are other things we can do to improve the accuracy. Meanwhile, we can get rather good performance with what we have today.
GPS World: What are some of your most recent advances, releases or products?
JF: On the timing side we have what we call a mini-Rubidium, the mRO-50, which we launched on June 4. Smaller, better, cheaper atomic clocks are coming out very soon.
GPS World: Do you have any comments on the recent executive order on resilient PNT?
JF: We coined the term “resilient PNT,” so we are glad to see it in use. We fully support those efforts.
GPS World: What about other alternative sources of PNT data, such as radar, lidar and signals of opportunity?
JF: Yes, they are that next level. Loran is ideal because it is so different from GNSS. When you are trying to design a reliable system, you want a lot of diversity, because if two systems have the same kinds of failure modes you have not gained in redundancy. Loran is literally at the other end of the spectrum from GNSS: It is a low-frequency microwave system. Instead of being space-based, it is land-based; instead of being low power, it is high power. However, there still are no stations up. It requires big equipment, so it will take some time.
When it comes to what you can do today, Loran does not contribute much. We support efforts to implement Loran very much, because we do need non-GNSS ways to make things resilient. Prior to GPS, we had to depend only on Loran. Today, with modern digital signal processing (DSP) techniques and receivers, I think we can expect the new Loran system to have much better accuracies than we had in the bad old days of the first generation of Loran.
The auto industry is doing a marvelous job of doing navigation using lidar or cameras. They are pretty much navigating driverless cars the way that humans drive, by just using visual cues. Those things have promise in certain unique areas.
What are the key technical criteria in matching GNSS receivers and antennas from the same or different manufacturers? For what uses does it matter most?
John Fisher. (Photo: Orolia)
“For fixed-pattern antennas, it’s fairly simple: RF + DC to power the antenna. Most vendors are compatible. The challenge is more for controlled radiation pattern antennas (CRPA). Power requirements vary greatly, and performance can be improved with a two-way data exchange between the CRPA and receiver, but there is no industry standard yet for this interface. An example: tilt angles from the receiver’s IMU can greatly aid beam pointing.” John Fischer Orolia
Ellen Hall
“Antenna selection is exceptionally critical for our military and high-precision users. The platform and environment are the primary drivers of these antenna requirements. In general, SWaP (size, weight and power) is at the forefront of all criteria. As operational plans are developed, requirements for a single or multi-element array, element gain, and noise figure must be considered.” Ellen Hall Spirent Federal Systems
Members of the EAB
Tony Agresta Nearmap
Miguel Amor Hexagon Positioning Intelligence
Thibault Bonnevie SBG Systems
Alison Brown NAVSYS Corporation
Ismael Colomina GeoNumerics
Clem Driscoll C.J. Driscoll & Associates
John Fischer Orolia
Ellen Hall Spirent Federal Systems
Jules McNeff Overlook Systems Technologies, Inc.
Terry Moore University of Nottingham
Bradford W. Parkinson Stanford Center for Position, Navigation and Time
