An exclusive interview with Jürgen Pielmeier, managing director, IFEN. For more exclusive interviews from this cover story, click here.
In which markets and/or applications do you specialize?
IFEN is offering RF simulation solutions for all GNSS markets, except the defense market with encrypted signals. The major market in recent years was the ‘New Space’ market, mainly focused to design and test PNT navigation solutions as part of (primarily) LEO satellite constellations using existing GNSS systems. With the many new players around the world, there are many market opportunities. To be successful in this ‘New Space’ market requires simulation support of all GNSS systems and signals, modelling LEO dynamics and environment and providing multiple RF-outputs (enabling systems with several GNSS antennas located on the satellite). With our latest ‘NCS NOVA+’ RF simulator, support of up to 4 RF-antenna simulations is possible. From basic RF system up to integrated SIL and HIL systems, the level of required solutions is very diverse by the different applications. The IFEN RF simulator is also offering a full ‘radio occultation’ simulation capability specifically for this market.
The second important market is the automotive/maritime PNT market requiring fully integrated HIL simulation solutions. Excellent integration capability into external environment simulation systems with a rich set of interfaces and short latencies are keys for this market. To further penetrate this market, IFEN will implement some major enhancements during this and next year within its RF simulator products.
How has the need for simulation changed in the past five years, with the completion of the BeiDou and Galileo GNSS constellations, the rise in jamming and spoofing threats, the sharp increase in corrections services, and the advent of new LEO-based PNT services?
Today, supporting all existing GNSS systems with all related signal components on all frequencies is a must have for all high-end RF simulators. Keeping the RF simulators up-to-date with the new and continuously evolving GNSS signals is required to be sustainably competitive. Specifically, beyond the L-band signals, we are also fully supporting the S-band signals of the NavIC constellation. The continuously increasing number of available GNSS satellites and signals requires that the RF simulator capabilities are fully scalable to provide sufficient resources to simulate all signal channels. Our new NCS NOVA+ simulator is our first RF simulator with strong scalability capabilities, to be further extended in the coming years.
In recent years, adding support for the simulation of jamming and spoofing threats was a major driver for the market. Our latest RF simulator generation ‘NCS NOVA+’ is fully supporting all types of jamming and spoofing, fully integrated into our RF simulators to enable coherent signal generation. With the coming ‘DFMC’ (SBAS/GBAS dual-frequency multi-constellation) based safety-of-life and automated driving applications, the need to support advanced jamming and spoofing simulation solutions will be a continuous driver also for the future.
Adding the ‘High Accuracy Service’ (HAS) PPP-correction capability on Galileo E6-B signal in our coming V2.9 release is driven by the increased request for PPP corrections services. We expect further improvements here in the coming years, especially to cover the emerging PPP-RTK market needs.
With the coming age of LEO-PNT services, this is the most important driver for the next five years, extending the signal frequencies beyond the current L- and S-band signals, seeing new modulations, two-way transfer and many more topics. This will require strong development efforts on the RF simulator side, to provide suited RF test tools in time to LEO-PNT system designers and developers, but also the related user terminal developers. IFEN is currently preparing to take this next major step in its RF simulator capability portfolio.
In particular, regarding some of the new PNT services being developed, how do you simulate them realistically without the benefit of recordings of live sky signals?
Facing the lack of live sky signals when developing RF simulator capabilities is a continuous challenge. It requires to a certain signal simulation flexibility designed into the receiver, good and theoretical understanding of specific implications of new designed signals. As soon as real signals are then available, simulation and real signals will be compared and if required the simulation fidelity will be adjusted to meet the real signals.
Are accuracy requirements for simulation increasing, to enable emerging applications?
Concerning the core accuracy parameters requested in recent years, we saw no increase in required accuracy, as the typical requested accuracy are anyway far beyond the real signals accuracy.
Are all your simulators for use in the lab or are some for use in the field? If the latter, for what applications and how do they differ from the ones in the lab? (For starters, I assume that they are smaller, lighter, and less power-hungry…)
Currently all our simulators are designed for usage within the laboratory. However, we recognize an increased request for in-field capable RF simulators, specifically to perform spoofing of real SIS to test deployed GNSS receivers in the field. Offering a portable in-field solution is in the mid-term planning, but not a current driver for our developments.
What are some of your recent successes?
The most important recent success is the Galileo 2nd generation Test User Receiver contract from the European Space Agency. Within this contract, the ‘NCS NOVA+’ simulator as RF test tool will be upgraded to full G2G signal generation capability. The new already implemented G2G signals enabling shorter TTFF, improved acquisition performance but also higher updates rates (e.g. for PPP-RTK). Up to end of the year the G2G signal will be fully implemented in our RF simulator, including the next generation of advanced authentication solutions.
An exclusive interview with Julian Thomas, managing director, Racelogic. For more exclusive interviews from this cover story, click here.
In which markets and/or applications do you specialize?
We originally designed our LabSat simulator for ourselves, because we supply GPS equipment to the automotive market. Then, we decided to sell it into that market, which is our primary market, for other people to use. That’s where we started, but it has moved on since then. We supply many of the automotive companies who use it for testing their in-car GPS-based navigation systems.
However, we’ve moved on to our second biggest market, which is the companies that make deployment systems for internet satellites, which use it for end-of-life testing. Several of our customers use it. That’s because we do space simulations, so we can simulate the orbits of satellites. That’s very useful when they’re developing their satellites.
We supply many of the major GPS board manufacturers — such as NovAtel, Garmin, and Trimble — when they’re developing their boards and testing their devices. We supply many of the phone companies — such as Apple and Samsung — and many of the GPS chip manufacturers — such as Qualcomm, Broadcom, and Unicom. More or less any company that’s into GNSS.
How has the need for simulation changed in the past five years, with the completion of the BeiDou and Galileo GNSS constellations, the rise in jamming and spoofing threats, the sharp increase in corrections services, and the advent of new LEO-based PNT services?
It all started off very simple, with just GPS, which was one signal and one frequency. We got that up and working very well and it helped us a lot. Then we got into this market. In the last few years, we’ve had to suddenly invent 15 new signals. We do two systems, really: one is a record-and-replay system. You put a box in a car, on a bike, in a backpack, or on a rocket, and you record the raw GPS signals; then you can replay those on the bench. That requires greater bandwidth, greater bit depth, smaller size, battery power, all of that.
The other is pure signal simulation. We simulate the signals coming from the satellites from pure principles. So, we’ve had to dive into how those signals are structured, reproduce them mathematically, and then incorporate that in into our software. That’s been 15 times the original work we thought it would be, but as we add each signal it tends to get a bit simpler until they add new ways to encode signals, and then it gets complex again. We’ve had to increase our bandwidth, increase our bit depth for the recording to cover all of these new signals.
Because our systems record and replay, they’re used a lot to record real-world jamming. In many scenarios, our customers will take one of our boxes into the field and record either deliberate jamming or jamming that’s been carried out by a third party. Then they can replay that in the comfort of their lab.
With regards to spoofing, we’ve just improved our signal simulation. So, we can completely synchronize it with real time. We can do seamless takeover of a GNSS signal in real time. We can reproduce the current ephemeris and almanac. If we transmit a sufficiently powerful signal, we can completely take over that device. Then we can insert a new trajectory into it. That’s a very recent update we’ve done.
If the complexity and amount of your work has gone up so much in the last few years but you cannot increase your prices at the same rate, what does that do to your business model?
It’s the same people that produce the signals in the first place, so they still have a job. However, as we add more signals and capabilities, we tend to get more customers as well.
Oh, so, you’re expanding your market!
Right, right.
Regarding some of the new PNT services being developed, how do you simulate them realistically without the benefit of recordings of live sky signals?
It is all pure signals simulation. You go through the ICD line-by-line and work out the new schemes. Here’s an interesting anecdote. Our developer who does a lot of the signal development is Polish and is also fluent in Russian. When we were developing the GLONASS signals, he was working from the English version of the GLONASS ICD. He said that it didn’t make any sense. So, he looked at the Russian version and discovered that the English one had a typo. When he used the Russian version, everything worked perfectly. He told this to his contacts at GLONASS and they thanked him and updated the English translation of their document. So, you are very, very much reliant on every single word in that ICD.
Are there typically differences between the published ICD and the actual signal?
No, no. Apart from the Russian one, which had a typo, they’re very good. For example, we’ve recently implemented the latest GPS L1C signal. My developer spent six months recreating it and getting all the maths right and the only way you could test it was to connect it to a receiver and hit “go.” It just worked the first time. He almost fell off his chair. The ICD in that case was very, very accurate.
Hope that Xona’s ICD is just as good.
Yeah.
Are accuracy requirements for simulation increasing, to enable emerging applications?
Yes, absolutely. No one can have too much accuracy. Everyone’s chasing the goal of getting smaller, faster, and more accurate systems. They want greater precision and better accuracy from their simulators, as well as a faster response. We do real-time simulators and they want a smaller and smaller delay from when you input the trajectory to when you get the output. Luckily for us, Moore’s law is still in effect, so, as the complexity of the signals and the accuracy requirements increase, computers can churn through more data. Luckily, we’re able to keep up on the hardware side as well, because much of our processing is done using software. Some companies do it in hardware and some companies do it in software. We concentrate on the software side of things.
Here’s another interesting anecdote from my Polish guy. He noticed that the latest Intel chips contain an instruction that multiplies and divides at the same time but that it wasn’t available in Windows. So, he put in a request with Microsoft for that operational code and they incorporated it into the very latest version of dotnet, which has improved our simulation time by 7%. I see little improvements like that all the time.
Are all your simulators for use in the lab or are some for use in the field? If the latter, for what applications and how do they differ from the ones in the lab? (Well, for starters, I assume that they are smaller, lighter, and less power-hungry…)
All our systems are designed to be used inside and outside the lab. They can all be carried in a backpack, on a push bike, in a car. We do that deliberately, because we come from the automotive side of things, so we have to keep everything very small and compact.
Besides automotive, what are some field uses?
Some of our customers have put them in rockets, recording the signal as it goes up, or in boats. We have people walking around with an antenna on their wrist connected to one of our systems, so that they can simulate smartwatches. There are many portable applications. We have a very small battery-powered version, which makes it very independent.
Are there any recent success stories that you are at liberty to discuss?
Our most exciting one is a seamless transition for simulation that we developed to replace or augment GPS in tunnels. We’ve been talking to many cities around the world that are building new tunnels. Because modern cars automatically call emergency services when they crash or deploy their airbags, they need to know where they are, of course. Cities need to take this into account when they are building new tunnels, which can pass over each other or match the routes of surface streets. Therefore, accurate 3D positioning in the tunnels has become essential. It requires installing repeaters every 30 meters along each tunnel and software that runs on a server and seamlessly updates your position every 30 meters. As you enter a tunnel, your phone or car navigation system instantly switches to this system. It’s been received very well because it’s mainly software and the hardware is pretty simple. We’ve brought the cost down to a fifth of the cost of standard GPS simulators for tunnels. So, we’re talking to several cities about some very long tunnels, which is very exciting.
An exclusive interview with Tim Erbes, Technical Director, Safran Federal Systems (formerly Orolia Defense & Security). For more exclusive interviews from this cover story, click here.
What are currently the key challenges for simulation?
One of our big challenges is determining what performance requirements are necessary for our users. Often, they can’t determine what the specs need to be. All they know is that they need it to work. “I need this receiver from one company, this IMU from another company, and the simulator I got from you guys to work together and I need the performance to match reality.” It can be very challenging to say, “What are the requirements for the simulator? How accurate does it need to be? What types of things matter in this integration?”
Often, we’re left trying to figure that out. So, that’s an interesting, maybe unexpected challenge. It’s easy to look at the datasheet and see what some specs are, but it’s a much harder thing to say, “Well, what do you need the specs to be?” So, we’ve been working with our customers to try to nail down some of those specs, particularly with Wavefront. We have some specs on such things as phase alignment and phase stability. But how do you translate that into something like “Well, I just want the CRPA to work the same in the lab as it does in the real world?” There’s not a direct, easy way to do that. We’re in the middle of trying to figure that out. That’s definitely one of our challenges.
What about the increase in jamming and spoofing threats?
In the last five years, we’ve seen a lot more open talk about jamming and spoofing in the world. The receiver manufacturers must think about this a lot more. What’s interesting from a simulator point of view is that this is not actually new for us. We have the advantage that we’ve been designing to program requirements for years and they have included jamming and spoofing for years. So, in a way, simulation is ahead of this state of the world. Jamming and spoofing are not new or hard ideas for us. In fact, spoofing is similar to simulation. So, we already know how to do that.
Image: Safran Federal Systems (formerly Orolia Defense & Security)
However, jamming and spoofing are new to programs and integration labs. So, there might be platforms where they’re now testing against jamming or spoofing requirements where in the past, maybe they didn’t do that. They certainly can use our simulators to help them do that. However, we’re not seeing a lot of new requirements coming to us saying we need new jamming or spoofing capabilities, because we already have them. Luckily, we are future oriented regarding the jamming and spoofing requirements, so those really haven’t been a challenge for us yet.
That can always change, right? If new requirements come up, such as higher data rates or wider bandwidth waveforms or different types of waveforms, then we would have to adapt and add support for that kind of stuff. As of right now, however, we aren’t really seeing that. So, luckily, we’re prepared for that. As for the industry as a whole, there has definitely been a big movement in the last few years to understand the effects of jamming and spoofing. Simulation is a big part of that.
What about the completion of the BeiDou and Galileo constellations?
For a long time, we simulated four constellations. Then that began to get fuzzy. Do you consider SBAS a constellation or is that just an augmentation? Do you count EGNOS and other supplemental constellations for the other constellations? What about NavIC and QZSS? Before you know it, you start to lose track of exactly how many you have. We just released our 8th constellation, Xona.We’re going to be demonstrating it at JNC.
Tell me more about that.
We are trying to have all the constellations and that can be a fuzzy definition. Does that mean all that are up there right now or all that will be up there in the future? We’re trying to be forward looking and add everything that is going to be up there or might be up there so that lab users can develop and test. Multi-constellation simulation is a particularly challenging problem for groups that don’t have simulators. If you’re just doing research on, say, GPS, and want a new code, you might be able to do that in a lab on your own. But as soon as you say, “I want to do research on whether this LEO constellation helps navigation on a receiver that also uses Galileo and GPS,” suddenly, your research requires a full multi-constellation simulation.
There are two choices. One is to have a simulator do the constellations that already exist, and then you have some research to add constellations. That can be very challenging, especially with time alignment and things like that. The other is to have a simulator that can do all the constellations. That would be the easy choice, right? That presents a problem with such things as LEO navigation being on the rise and these constellations that are just emerging, that are still not even fully defined.
So, we’re trying to build those into our simulation products, to help researchers and decision makers determine whether these will be useful features to add to their receivers or their systems. We have the advantage of having a software-defined architecture. We designed the software so that it is easy to add new constellations to it. Basically, once we’re given a proper ICD, we’re only a couple of months away from a first draft implementation of that new signal. Then we iterate. There used to always be a government-driven, multi-year program to develop an ICD. Now, we have this new concept of the signal manufacturers. We’re seeing private companies release signal specs. That’s a very different way of creating a signal in a constellation. So, sometimes you don’t get much time between when the ICD is available and when simulator users want to use that constellation. Having a software-defined architecture really helps us move quickly. We can add such things as Xona very fast.
Xona told me a couple of days ago that they will soon put out an ICD. What’s the difference between actual signals that you can record and play versus something that’s only on paper?
That’s a great point. Probably many people don’t realize, when they first look at this, that what’s in the ICD and what’s on live sky are sometimes very different. Is the simulator supposed to match live sky? Or is it supposed to match the intended final state of the constellation, according to the ICD? This is a huge topic for M-Code, which is ever changing, and has a very large ICD that’s been released. Space Systems Command/Military Communications & Position, Navigation, & Timing (MCPNT) controls the features and releases them incrementally. We’re constantly having to make changes to the simulator to match those releases. The same is true for the other ICDs. At the Institute of Navigation Joint Navigation Conference (JNC), we will demonstrate an expanded PRN. I think this showed up in the ICD a couple of years ago, but it’s not used by any users yet. Some of the receiver manufacturers are starting to look at using PRNs beyond 32. So, we’re adding that to the simulator. This has already happened for BeiDou as well. I think their ICD goes up to more than 60 satellites. It’s an ever-changing race. The ICDs are constantly being updated and we’re trying to update the simulator.
Image: Safran Federal Systems (formerly Orolia Defense & Security)
Meanwhile, live sky is many years behind the paper, right? This creates an interesting challenge: when you design a system, are you designing it for today or for the future? We have users in both groups. We have users that only care about what is happening today, because they need a model. Maybe you want to model a specific mission and you want to make sure that everything’s going to go properly. Or maybe you’re designing a system that you want to release in three or four years, and you want to make sure that it’s going to work with the state of the system then.
A big challenge is to make sure that we’re keeping pace with all these ICDs. There are more constellations than ever and the technology makes it easier to change signal architectures. We’re seeing signals change faster than we’ve ever seen them change before. We go to conferences and hear about such things as on-orbit reprogramming and signals that might even change specs while they’re being transmitted. Maybe they don’t even have to have a fixed bandwidth or fixed bit rate. We’re going to start talking about signals that can reprogram on the fly. That’s going to make simulation more and more challenging. The technology exists to do this.
Software-defined waveforms is a very logical step. In the software world, we have this concept of version nightmare. When you have 20 different pieces of software that are interdependent, it can get very challenging. We’re going to start to see that in simulators. We’re going to see, “Hey, what version of navigation authentication are you using? We updated it six months ago. Are you using the new one or the old one? Which one should we use?” Well, it depends on what your receiver is using. It’s going to be interesting and challenging to keep all this straight in the next few years as things evolve. Certainly, however, our goal is to be there for all of it and to be as fast and as forward thinking as we can for our customers. That means that we also need to know what our customers need. So, we’re always looking for feedback and requests, what challenges our customers face and we’re responding to those requests.
Tell me more about the difference between simulators used by receiver manufacturers in their labs as they’re tweaking receivers or developing new ones vs. simulators used for mission planning.
The simulators are the same, but they’re used in very different ways. In most lab simulation, what the constellation looks like that day doesn’t matter very much. They can just run with a default constellation for a given day. They’ll run that scenario hundreds or thousands of times and never need to change it because they’re testing parts of the receiver that don’t care a whole lot about the specifics of what’s happening.
Whereas missions are time- and location-specific.
Yeah, exactly. They want to know which satellites will be overhead at an exact time and place. It’s not so much a problem anymore, but there used to be certain days and times when you would not get enough satellites in view, or you might have very bad dilution of precision, and your mission might actually fail. We’re past those days. There are now enough satellites up there. Most receivers will navigate within their specs most of the time in most places. However, for critical missions, such as military operations or rocket launches, you might not want to just assume that any day is a good day. So, if you’re about to launch a rocket, you might want to check. “What does the constellation look like right now?” The challenges that brings is that simulators have a default constellation, but the constellations are constantly changing.
When you’re doing real day mission planning, the big problem isn’t so much how to generate a signal, it’s how to find out what’s happening today. That’s really the nature of the problem because what’s out there today is different from what was happening yesterday or what will happen tomorrow. You might have unhealthy satellites. You need to know that if you want to model them. It becomes a big challenge to get all the right data into the simulator. Once all that data is in there, then it’s the same as any other simulation.
Are there good sources for current data on GLONASS, BeiDou and Galileo?
Image: Safran Federal Systems (formerly Orolia Defense & Security)
There are a couple of websites that provide information about where the satellites currently are. However, we’ve found that each one of those sites has its own challenges. Some are maybe 30 minutes out of date, which is pretty good, but puts the satellites in slightly different spots. Some of those sites only support some of the constellations. We’re talking about multiple countries and they don’t all agree on how this should be done. So, there’s not a single point that you can visit to get all the satellite data. There are a couple of companies that try to fix this. U-blox has AssistNow; Qualcomm has an assist for its cellular receivers; Trimble, NovAtel, and a couple of other companies have their error correction services to which you can subscribe to get some of that data.
If you want real-time up-to-date ephemeris for all the constellations, that is challenging. There are one or two options we have found that seem to work, but they each have their disadvantages. Maybe they don’t have all the satellites. Again, we’re talking about versioning issues. So, if you’ve designed your system with a certain version of an ICD and they’ve added more satellites since, those new SVs maybe aren’t so important for your users, so you don’t publish them. Other users want those satellites. So, we see versioning issues in these data streams. For example, we use the CORS network to get a lot of GPS data but that whole network, as far as I know, is only running the legacy data. As far as I know, no network is distributing the L1C modernized data that we will need at some point. So, as we launch new signals and constellations, we need the networks to provide this new data.
What are some other challenges?
For us, being a software-defined simulator on a platform dependent on software-defined radio (SDR), we’re constantly looking at what’s changing in the SDR technology community. There’s always some interesting stuff happening there that we try to incorporate. We don’t have any big announcements this year, as far as new architectures or anything like that. However, the SDR community is evolving. It’s still a rather new industry. A few years ago, we were an early adopter of SDR technology for mass deployment. Now, we’re seeing some more mature SDRs starting to push such things as channel count and coherency. We will probably take advantage of that in the future.
The other interesting thing technology-wise is that we’re also a GPU-dependent technology. So, as the GPU industry continues to evolve and makes bigger and faster GPUs, we get a relatively low-cost way to upgrade. We don’t have to do a lot of R&D to upgrade to a new GPU. For our users that means that the number of signals they can generate on their simulators is always increasing even using the same hardware from one generation to the next. Our first simulator did 75 signals; the next version did 150. We could build a system that did more than 1,000 signals, but our users don’t need it.
I assume that the growth curve for GPUs is steeper than that for signals.
I think that you’re right about that. I’m sure glad they do, because then something like Xona shows up and we don’t have to rearchitect our system to generate 300 signals, right? At JNC we will show expanded PRN, 300 Xona satellites in the constellation, and a 10 fold improvement on Wavefront performance specs.. We will continue to build simulators that meet our customers’ requirements. Besides GPUs, a lot of the technology involves software R&D and signals. The stuff that we do digitally inside of our system that allows us to do things like extremely precise phase alignment on Wavefront, for example. We spent a lot of time developing that stuff.
Image: Safran Federal Systems (formerly Orolia Defense & Security)
As the number of constellations, satellites, and signals has grown in recent years — especially in the past few years, with the completion of the BeiDou and Galileo constellations — simulator manufacturers have been challenged to keep up. Threats of jamming and spoofing also increased. Then, a few companies began to develop new positioning, navigation and timing (PNT) constellations in low-Earth orbit (LEO).
Due to the limited space available in print, I was able to use only used a small portion of the interviews I conducted for our August cover story. For full transcripts of them see below:
Full interview with Tim Erbes, Technical Director, Safran Federal Systems (formerly Orolia Defense & Security).
Full interview with JulianThomas, Managing Director, Racelogic.
Full interview with Jürgen Pielmeier, Managing Director, IFEN.
Full interview with Mark Holbrow, VP of Product Development, Spirent Communications and Roger Hart, Sr. Director of Engineering, Spirent Federal Systems.
Spirent’s GSS6450 record and playback system (RPS) used to record live-sky signals in an urban environment for testing in the lab.(Image: Spirent Federal Systems)
These are interesting and challenging times for the makers of GNSS signal simulators.
For decades, developers and manufacturers of GNSS receivers have needed to simulate the satellites’ signals to test receivers in their labs and in the field. Meanwhile, users of GNSS receivers for critical missions — such as military operations and rocket launches — have needed to simulate the exact conditions (the number of satellites in line of sight, the positional dilution of precision, etc.) at specific points in time and space.
As the number of constellations, satellites and signals grew — especially in the past few years, with the completion of the BeiDou and Galileo constellations — simulator manufacturers were challenged to keep up. Threats of jamming and spoofing also increased. Then, a few companies began to develop new positioning, navigation and timing (PNT) constellations in low-Earth orbit (LEO). Now, it is common for simulators to require several hundred channels.
I discussed these challenges and the prospect for the simulation industry with representatives of five companies:
Tim Erbes, Technical Director, Safran Federal Systems (formerly Orolia Defense & Security
For the full transcripts of my interviews, click here. If you like this article, you will love the interview transcripts, which cover much more than I had room for here.
Legacy Constellations and New Ones
Simulator manufacturers cite a variety of challenges. According to Erbes, a big one is determining users’ requirements. “Often,” he said, “they can’t determine what the specs need to be. All they know is that they need it to work.” This is particularly true when mixing and matching receivers, IMUs, and components from different manufacturers, he pointed out.
For decades, there were only two GNSS constellations (GPS and GLONASS). A couple of years ago, two more came online (BeiDou and Galileo). Meanwhile, several regional augmentation systems were developed (SBAS, EGNOS, NavIC, QZSS and KASS), some of which may later grow into global systems. Now, new LEO-based systems are being developed. For simulator manufacturers, what was once clear “began to get fuzzy,” Erbes said. “If you ask members of our team right now how many constellations we support, you will not get a quick answer. We’re trying to be forward-looking and add everything that might be up there so lab users can develop and test.”
Multi-constellation simulation is a particularly challenging problem for groups that don’t have simulators, Erbes pointed out. “We have the advantage of having a software-defined architecture. We designed the software so that it is easy to add new constellations to it. Basically, once we’re given a proper interface control document (ICD), we’re only a couple of months away from a first draft implementation of that new signal. Then we iterate.”
In the past few years, said Thomas, Racelogic “had to suddenly invent 15 new signals.” It makes a record-and-replay system — “You put a box in a car, on a bike, in a backpack, or on a rocket, and you record the raw GPS signals,” Thomas said — and another system in which it simulates the satellites’ signals “from pure principles.” The latter, he noted, has been “15 times the original work we thought it would be. However, as we add each signal it tends to get a bit simpler until they add new ways to encode signals, and then it gets complex again.”
Spirent Communications’ technology, Holbrow said, focuses around “its dedicated SDR hardware platform and software simulation engine, which provide performance, scalability and flexibility, within an open accessible architecture. Close collaboration with our selected partners ensures the opportunity to support and integrate new and emerging PNT technologies through their tools, applications and hardware.” Two other aspects that have continued to grow in importance have been “increased realism and test automation,” Holbrow said. “Both are areas in which Spirent continues to prioritize and invest R&D dollars.”
Spirent “can enable the user with effectively an arbitrary waveform simulator or ‘sandbox’ to experiment with different modulation schemes, different chipping rates, codes, bandwidths and navigation data content,” Holbrow said. “The increasing number of signals that we can support multiplies the permutations and combinations of test cases that users can do,” Hart added.
Not every simulator user is equally interested in simulating all the existing and emerging constellations. Those in the U.S. military market do not use foreign signals, pointed out Clark. However, they may want to understand how those signals could impact their vehicle, platform, or individual receiver.
LEO-based constellations “have become a buzzword in the last year or so,” Clark said. Because CAST Navigation’s simulators are modular and use an FPGA-based design, “we can add different satellite constellations or satellite protocols to our system,” he said. “However, we don’t offer anything commercially yet due to a lack of an official ICD, or any kind of documentation that defines any of these new LEO-based signals.”
Today, said Pielmeier, all high-end RF simulators must support “all existing GNSS systems with all related signal components on all frequencies.” Additionally, to remain competitive, they must be kept “up-to-date with the new and continuously evolving GNSS signals.” He added: “Beyond the L-band signals, we are also fully supporting the S-band signals of the NavIC constellation.”
The increased request for precise point positioning (PPP) corrections service, Pielmeier pointed out, was the driver for IFEN to add the High Accuracy Service (HAS) PPP-correction capability on Galileo’s E6-B signal to its next release. “We expect further improvements here during the next few years, especially to cover the emerging needs of the PPP-RTK market.” The advent of LEO-based PNT services, he said, makes this “the most important driver for the next five years, extending the signal frequencies beyond the current L- and S-band signals, seeing new modulations, two-way transfer and many more topics.”
Jamming and Spoofing
Concern about jamming and spoofing has increased significantly over the past several years. These, however, are not new concepts for simulator manufacturers. “In a way, simulation is ahead of this state of the world,” said Erbes. “Spoofing is similar to simulation. So, we already know how to do that.” That could change, however. “If new requirements come up, such as higher data rates or wider bandwidth waveforms or different types of waveforms, then we would have to adapt and add support for that kind of stuff.”
“Because our systems record and replay, they’re used a lot to record real-world jamming,” said Thomas. Regarding spoofing, Racelogic has just improved its signal simulation. “We can do seamless takeover of a GNSS signal in real time. We can reproduce the current ephemeris and almanac. If we transmit a sufficiently powerful signal, we can completely take over that device.”
Over the past five years, most of CAST Navigation’s customers have become much more interested in being able to simulate jamming and spoofing, Clark said. “If you’re doing anything of any importance in a contested environment, you’re going to come up against some type of spoofing and/or jamming interference.”
Pielmeier agreed that simulation of jamming and spoofing threats has been a major market driver in recent years. “Our latest RF simulator generation, NCS NOVA+,” he said, “fully supports all types of jamming and spoofing and is fully integrated into our RF simulators to enable coherent signal generation. With the coming safety-of-life and automated driving applications based on DFMC (SBAS/GBAS dual-frequency multi-constellation), the need to support advanced jamming and spoofing simulation solutions will remain a continuous driver.”
IFEN’s rf signal generator technology, based on a modular and highly flexible Software Defined Radio (SDR) platform. (Image: IFEN)
Simulating What Does Not Yet Exist
The current GNSS constellations broadcast signals that can be recorded, played back, and used to generate accurate simulations. For systems still being developed, however, simulator manufacturers must rely on each system’s ICD, if and when it is available. Even for established systems, the live sky signals may diverge from the ICD. “Is the simulator supposed to match live sky,” Erbes wondered, “or is it supposed to match the intended final state of the constellation, according to the ICD? This is a huge topic for M-code, which is ever changing, and has a very large ICD that is released incrementally. We’re constantly having to make changes to the simulator to match those releases.”
A big challenge for simulator manufacturers is to keep pace with new and evolving ICDs. “There are more constellations than ever, and the technology makes it easier to change signal architectures,” said Erbes. “We’re going to start talking about signals that can be reprogrammed on the fly. That’s going to make simulation more and more challenging.”
Simulating signals for new systems that are not yet deployed is a matter of “pure signals simulation,” said Thomas. “You go through the ICD line-by-line and work out the new schemes. You are very much reliant on every single word in that ICD.”
New LEO-based systems are not the only ones to present this challenge to simulator manufacturers. “L1C is another one of those problem child signals that we have developed,” said Clark. “All we can do is buy all the makes and models of L1C receivers available for sale and utilize our simulator, along with those receivers, to see whether things are good. We’ve asked the government for an L1C code sample, but it will not be available until the satellite manufacturers launch the satellites in their final configuration. Until then, we’ll develop to the ICD that’s been released and defined, then cross our fingers.”
Spirent’s core simulation engine and SDR “are agnostic of the constellation and signal type that’s being generated,” Holbrow said. “So, the underlying principles of accuracy, range rate, pseudo-range control, and delay, together with the RF fidelity from Spirent’s SDR+ Sim engine, can be readily manipulated to simulate the wealth of emerging signals, including LEO.” Additionally, when an ICD is not available, the company can enable its customers to use its tools “to readily populate elements of that ICD themselves.”
In the Lab vs. In the Field
“All our systems can be carried in a backpack, on a push bike, in a car,” said Thomas. “We do that deliberately, because we come from the automotive side of things, so we have to keep everything very small and compact. Some of our customers have put them in rockets, recording the signal as it goes up, or in boats. We have people walking around with an antenna on their wrist connected to one of our systems, so that they can simulate smartwatches.”
CAST Navigation has simulator packages that range “anywhere from shoebox size to nine-foot-tall racks,” said Clark. “They are all modular, so you can add options and capabilities over time. We have simulators that are used in the field. Some of the testing groups with the U.S. armed forces have used our simulators in the back of a Humvee along with other proprietary equipment to conduct their own field experiments.”
Spirent supports in-the-field use cases: its portable simulator can test PNT resilience while the DUT is receiving live-sky signals, and their record-and-playback system takes real-world soundings in a wideband RF environment for playback in the lab.
Currently, Pielmeier said, all IFEN simulators are designed for lab use. However, “we recognize an increased request for field-capable RF simulators, specifically to perform spoofing of real SIS to test deployed GNSS receivers in the field. Offering a portable in-field solution is in our mid-term planning, but not a current driver for our developments.”
Testing vs. Mission Planning
How do simulators used by receiver manufacturers in their labs and in the field to tweak existing receivers or develop new ones differ from those used for mission planning? “In most lab simulations, they can just run with a default constellation for a given day,” Erbes explained. “They’ll run that scenario hundreds or thousands of times and never need to change it because they’re testing parts of the receiver that don’t care a whole lot about the specifics of what’s happening.”
Missions, by contrast, are time- and location-specific. Planners need to know which satellites will be overhead at an exact time and place. “When you’re doing real day mission planning, the big problem isn’t so much how to generate a signal, it’s how to find out what’s happening today.”
Increasing Accuracy Requirements
Like those for receivers, accuracy requirements for simulators are increasing to match those of emerging applications. “Everyone’s chasing the goal of getting smaller, faster, and more accurate systems,” said Thomas. “We do real-time simulators, and they want a smaller and smaller delay from when you input the trajectory to when you get the output. Luckily, we’re able to keep up on the hardware side as well, because much of our processing is done using software.”
As accuracy requirements rise, “Real-world testing has an incredibly important role to play,” said Holbrow. Additionally, as resilience testing places increasing demands on test equipment, Spirent Communications now supports “a multitude of vulnerability and corresponding mitigation/prevention test cases” to deal with jamming, spoofing, cyber-attack and CRPA
CAST Navigation’s simulators meet or exceed accuracy requirements, Clark said. “We have pseudo-range accuracy down to a millimeter, our phase coherence doesn’t wander, and we’re able to achieve 2.5 ps to 3 ps synchronization coherence during multi-element, phased-array antenna simulations. We see our customers interested in a higher performing simulator, and that is our commitment.”
Pielmeier had a different perspective on this: “We saw no increase in the required accuracy, as the typical requested accuracies are far beyond the real accuracy of the signals anyway.”
Recent Success Stories
Racelogic has developed a system to replace or augment GPS in tunnels, which often pass over each other or match the routes of surface streets. “We’ve been talking to many cities around the world that are building new tunnels,” said Thomas. “It requires installing repeaters every 30 meters along each tunnel and software that runs on a server and seamlessly updates your position every 30 meters.”
Clark pointed out that CAST Navigation’s “bread-and-butter” for the past few years has been “larger systems that can drive phased array antennas, along with inertial units, and full high-dynamic aircraft, in real-time environments.” He added that “the smaller systems, which used to be popular, have mostly gone by the wayside.”
As a recent success, Holbrow cited Spirent Communications’ release of a Xona simulator, in partnership with Xona Space Systems, as well as the addition of “many realism-related capabilities, including simulating the vibration and temperature effects of inertial systems;” a cloud-based software application called Foresight that enables users to understand the GNSS coverage they would expect at a particular time, location and trajectory based upon accurate 3D scenes; and a simulation test solution for the Galileo Open Service Navigation Message Authentication (OSNMA) mechanism. Finally, he stressed Spirent’s increasing support for automation.
Pielmeier cited the Galileo second generation Test User Receiver contract that IFEN received from the European Space Agency as its most important recent success. “Within this contract, the NCS NOVA+ simulator as RF test tool will be upgraded to full G2G signal generation capability. The new already implemented G2G signals enable shorter time to first fix (TTFF) and improved acquisition performance but also higher updates rates (e.g., for PPP-RTK). Through the end of the year, the G2G signal will be fully implemented in our RF simulator, including the next generation of advanced authentication solutions.”
Sitting comfortably in a thin aluminum tube at 35,000 ft, I can continue to communicate via e-mail — and, soon, via video — and write this editorial, while on my way from Portland, Oregon, where I live, to Cleveland, Ohio, where North Coast Media, this magazine’s publisher, is based.
I can safely assume that the pilot knows our position, heading, and speed with great accuracy and receives excellent weather reports. The computer on my wrist (made by the largest manufacturer of GNSS-based consumer devices) and the much more powerful one in the holster on my belt, can do way more than Dick Tracy’s creator, Chester Gould, could have ever imagined a gadget produced by Diet Smith Industries to do.
One thing that communications, navigation, and weather forecasts currently share is reliance on satellites — be they in geostationary Earth orbit (GEO), at 22,000 mi, which are used mostly for weather data, broadcast television and, increasingly, data communication; medium Earth orbit (MEO), at 3,000 mi to 12,000 mi, including GNSS satellites and those that provide Internet connectivity; or low-Earth orbit (LEO), 300 mi to 745 mi, with thousands of satellites in operation today, primarily addressing science, imaging, and low-bandwidth telecommunications needs — and, coming, a new generation of satellite-based positioning, navigation, and timing (PNT) services.
Another thing these feats of engineering share is their foundation on the purest science and mathematics. To take one example, had the designers of GPS failed to adjust the system by 38 ms per day to account for both Albert Einstein’s 1905 Special Theory of Relativity and his 1915 General Theory of Relativity, positional errors would cumulate at a rate of about 6.2 mi each day, making GPS utterly worthless for navigation in a very short time. That’s because Einstein’s 1905 theory leads to the prediction that the atomic clocks on GPS satellites should fall behind clocks on the ground by about 7 ms per day because of their slower ticking rate due to the time dilation effect of their relative motion — while his 1915 theory leads to the prediction that they would be ticking faster than identical clocks on the ground by 45 ms per day due to the curvature of spacetime.
As with most complex technologies, the scientific principles, technical challenges, and policy debates behind GNSS are unknown and irrelevant to more than 99% of the public, few of whom even know that GPS is not the only global navigation satellite system in existence today. The technology is transparent to them. Most of them say “GPS” to refer to GNSS receivers, digital maps, driving directions and traffic data without understanding the separate, though overlapping, technologies, business models and data sources involved. This routinely results in misunderstandings and misattributed complaints and praises — such as when drivers blame “their GPS” (meaning their GPS receiver) for leading them up a dead end that was due to a mapping company being one step behind new construction or praise it for traffic alerts for which they should thank crowd-sourced data and algorithms.
The Institute of Navigation’s Military Division hosted the 2023 Joint Navigation Conference (JNC 2023) for the Department of Defense andthe Department of Homeland Security, in San Diego, June 12 to 15. JNC, the largest U.S. military positioning, navigation and timing (PNT) conference of the year, was attended by 1,162 people. The theme of this year’s conference was “Enhancing Dominance and Resilience for Warfighting and Homeland Security PNT” and it focused on technical advances in PNT with emphasis on joint development, test and support of affordable PNT systems, logistics and integration. GPS World was one of the event’s media partners. For information on future JNC events, click here.
Image: Institute of NavigationImage: Institute of Navigation
Autonomy & sustainability
Image: HEXAGON
More than 3,600 professionals, business owners, thought leaders and media analysts from 77 countries met in Las Vegas on June 12 to 15 for HxGN LIVE Global, Hexagon’s largest event of the year. In his opening keynote address, the company’s president and CEO, Paolo Guglielmini, announced an exclusive new collaboration between Hexagon and Nvidia to transform industrial digital twin solutions that unite reality capture, manufacturing twins, AI, simulation and visualization to deliver real-time comparison to real-world models using NVIDIA Omniverse, a platform for developing and operating industrial metaverse applications. The conference included panel discussions, general sessions and break-out sessions with presentations by industry experts, as well as hands-on demonstrations in the exhibit hall, called The Zone. Other events included a Women in Tech lunch and ahuge party on Wednesday night.
“Could a new PNT constellation using LEO satellites fully replace the services provided by the four existing GNSS constellations?”
Mitch Narins
“From a pure capabilities standpoint, the answer is “Yes”. LEO constellations can provide the PNT performance metrics that users require. However, should this strategy be followed, it would lack the diverse, complementary solutions needed to ensure the safety, security, and efficiency of critical infrastructure. Many have recognized the need for resilient PNT solutions and identified system-of-systems approaches. Multiple satellite constellations — MEOs and LEOs (despite the number of platforms) — lack this needed resilience. A resilient system-of-systems should include satellites in multiple orbits and complementary ground-based PNT infrastructure, each providing needed performance and overall demonstrating resilience from diverse threats.”
— Mitch Narins Strategic Synergies
John Fischer
“In theory, yes. With a much stronger signal (antijam) that is encrypted (antijam), they counter GNSS’s two main vulnerabilities. However, with a paid service business model, it is difficult to compete with a free service. Moreover, large constellations are needed to overcome GDOP. OneWeb, Starlink, et al. already have launched and will continue to launch large constellations, so they must compete with these high bandwidth communications constellations that can provide accurate PNT as a side service and don’t have a GDOP limitation because of their size. Adoption of a single-purpose PNT system will be difficult.”
— John Fischer Orolia
Bernard Gruber
“Yes, it could. That said, as with any new product or technology, evolution of PNT capabilities will be dependent on competition, value or threats that undermine the current environment. Burgeoning systems such as Xona, Satelles or any number of augmentations utilizing “signal of interest” such as Starlink will rightly contribute to the evolution of enhanced PNT. Current advantages of LEO-based systems such as increased received power, decreased convergence time and numerical diversity are noteworthy, but replacing an investment of $100B+ government backed GNSS systems that adhere to well established policies and published ICDs is another.”
— Bernie Gruber Northrop Grumman
Jules McNeff
“As my colleagues above note, the answer is yes from a technical perspective. However, in practice, not so much. Even with software-defined receivers, issues of signal reception and processing, interface standards, comm/nav service prioritization, security, integration into complex systems, integrity assurance, etc. make use of such nav services in lieu of purpose-built GNSS services impractical.”
Advanced industrial societies are increasingly reliant on the fantastic capabilities of global navigation satellite systems (GNSS) — GPS, GLONASS, BeiDou and Galileo — and, therefore, increasingly vulnerable to their weaknesses. From providing our position on a map on our smartphone to timing financial transactions, cell phone base stations, and the internet; from steering tractors in the field to guiding first responders; from giving surveyors sub-centimeter accuracy to monitoring continental drift; from providing navigation to ship captains and airplane pilots, to enabling automated control of earth moving machinery, GNSS have become a critical infrastructure. Yet their well-known vulnerabilities — such as jamming, spoofing, multipath and occultation — continue to fuel the development of complementary sources of positioning, navigation and timing (PNT) data, especially for new and rapidly expanding user segments such as autonomous vehicles.
In a January 2021 report, the U.S. Department of Transportation pointed out that “suitable and mature technologies are available to owners and operators of critical infrastructure to access complementary PNT services as a backup to GPS.”1
Several new PNT systems are being developed and deployed that are partially or entirely independent of the four existing GNSS constellations. This cover story focuses on the following companies, products and services:
Safran Federal Systems (formerly Orolia Defense & Security) makes the VersaPNT, which fuses every available PNT source — including GNSS, inertial, and vision-based sensors and odometry. I spoke with Garrett Payne, Navigation Engineer.
Xona Space Systems is developing a PNT constellation consisting of 300 low-Earth orbit (LEO) satellites. It expects its service, called PULSAR, to provide all the services that legacy GNSS provide and more. I spoke with Jaime Jaramillo, Director of Commercial Services.
Spirent Federal Systems and Spirent Communications are helping Xona develop its system by providing simulation and testing. I spoke to Paul Crampton, Senior Solutions Architect, Spirent Federal Systems as well as Jan Ackermann, Director, Product Line Management and Adam Price, Vice President – PNT Simulation at Spirent Communications.
Satelles has developed Satellite Time and Location (STL), a PNT system that piggybacks on the Iridium low-Earth orbit (LEO) satellites. It can be used as a standalone solution where GNSS signals will not reach, such as indoors, or are otherwise unavailable. I spoke with Dr. Michael O’Connor, CEO.
Locata has developed an alternative PNT (A-PNT) system that is completely independent from GNSS and is based on a network of local ground‐based transmitters called LocataLites. I spoke with Nunzio Gambale, founder, chairman, and CEO.
Due to the limited space available in print, this article only uses a small portion of these interviews. For full transcripts of them (totaling more than 10,000 words) click here.
1 Andrew Hansen et al., Complementary PNT and GPS Backup Technologies Demonstration Report, prepared for the Office of the Assistant Secretary for Research and Technology, Department of Transportation, January 2021, p. 195.
Locata dish antenna pointed to the European Union’s Joint Research Center in Ispra, Italy, 44 km away, just under the setting sun. The Yagi antenna above is pointed to a cell tower in Como and used to connect the system for remote control and data logging. (Image: Locata)
Complementary PNT
“Traditionally, augmentation to GNSS has been done through inertial navigation systems (INS),” Price said. “More recently, ground- and space-based augmentation systems have increased in usage. However, both technologies depend on the absolute positioning information provided by GNSS. They do not represent a true alternative PNT.”
To facilitate the development of advanced and autonomous applications, Price suggested incorporating terrestrial sources of PNT as well as ones based on LEO, medium-Earth orbit (MEO) and geostationary equatorial orbit (GEO) satellites. This, he added, would also keep costs from becoming prohibitive. “LEO brings many benefits in comparison to MEO in just about every industry to which it can be applied,” Jaramillo said.
While mass reliance on GNSS facilitates access to GNSS data and makes devices that use it increasingly cost-effective, over-reliance on a single sensor is risky, Austin pointed out.
“That’s where complementary PNT comes in: if you can put your eggs in other baskets, so you have that resilience or redundancy, then you can continue your operation — be it survey, automotive or industrial — even if GNSS falls or is intermittently unavailable or unavailable for a long time,” Austin said.
It has been said that “the only replacement for GNSS is another GNSS.” Inertial navigation, dead reckoning, lidar, and referencing local infrastructure that, in turn, has been globally referenced using GNSS, enable mobile platforms to maintain relative positioning during GNSS outages. However, absolute positioning will continue to require GNSS. “If you claim to be breaking free from GNSS you’re really saying, ‘I can navigate in this building, but I don’t know where this building is,’” Austin said.
GNSS-INS Integration
GNSS and INS have always been natural allies because they complement each other. The recent completion of the BeiDou and Galileo constellations, which has greatly increased the number of satellites in view, has made the requirement for six satellites at any one time for real-time kinematic (RTK) “a much more reasonable proposition,” Austin said. Coupled with the drop in the price of inertial measurement units (IMU), this has made it possible to “make a more cost-effective IMU than ever or spend the same and get a much better sensor than you ever could before,” he said. “Your period between the GNSS updates is also less noisy and you have less random walk and more stability.”
It used to be that the performance of an accelerometer might far outweigh that of a gyroscope, resulting in excellent velocity but poor heading. “Now,” Austin said, “we can pick a much more complementary combination of sensors and manufacture and calibrate an IMU ourselves while using off-the-shelf gyroscopes and accelerometers. That allows us to make an IMU that is effectively not bottlenecked in any one major area.”
Autonomous vehicles require decimeter accuracy to keep to their lane, while their absolute position is irrelevant to that task. It is, however, essential for map navigation and to know about infrastructure such as traffic signs and stoplights that may not be in a vehicle’s line of sight.
“That’s where the global georeferencing comes in and where GNSS remains critical,” Austin said. “One of the key things we’re examining is GNSS-denied navigation: how we can improve our inertial navigation system via other aiding sources and what other aiding sensors can complement the IMU or inertial measurement unit to give you good navigation in all environments. Use GNSS when it’s good, don’t rely on it when it’s bad or completely absent.”
Nowadays, car makers are increasingly moving their research and development tests from indoor, controlled environments to open roads. Therefore, “they are looking for a technology that allows them to keep doing those tests that they did on the proving ground, but in real world scenarios,” Austin said. “So, they rely on the INS data to be accurate all the time. In autonomy and survey, on the other hand, the INS is used actively to feed another sensor to either georeference or, in the case of autonomy, actively navigate the vehicle. So, that data being accurate is critical because an autonomous vehicle without accurate navigation cannot move effectively and would have to revert to manual operation.”
Image: Xona Space Systems
New vs. Old
Complementary PNT systems differ from legacy GNSS along several variables. One is coverage. For example, Satelles and Xona will provide global coverage, while Versa PNT and Locata are local. Another is encryption. Unlike GPS, which encrypts only its military SAASM/M-code signal, Xona’s PULSAR system will encrypt all its signals, Jaramillo said. “For autonomous applications, security is very important. If you’re riding in an autonomous car, you certainly don’t want somebody to be able to spoof the GNSS signal and veer it off course.”
Additionally, the design of Xona’s constellation includes a combination of polar and inclined orbits, which will greatly improve coverage in the polar regions compared to current GNSS coverage. This is particularly important as climate change makes the arctic more accessible. “The idea of having a LEO-based constellation is to take advantage of what can be done in LEO for GNSS,” Jaramillo said. “If you want the most resilient time and position, you need to use a combination of everything.”
Based on its architecture, Jaramillo said, Xona will provide better timing accuracy than GNSS does today. “Our satellites are designed to use GPS and Galileo signals, as well as inputs from ground stations, for timing reference and will share their time amongst themselves. We will average all these timing inputs and build a clock ensemble on the satellites. That enables much higher accuracies than just having a few single inputs.”
Satelles’ STL service can either substitute for GNSS where the latter is unavailable or supplement it where it is available. When used as a supplement, “the goal is having a solution that is resilient to an outage, interference, jamming, spoofing, those sorts of things,” O’Connor said. “In that case, the receiver card that might be provided by one of our partner companies would have both GNSS and STL capabilities and would take the best of both worlds.” Depending on the product configuration, its locational accuracy is generally in the 10- to 20-meter range, O’Connor said.
Orolia Defense & Security’s Versa PNT “is an all-in-one PNT solution that provides positioning, navigation, and very accurate timing,” Payne said. “Every type of sensor that you’re using for PNT has its strengths and weaknesses. That’s why we have a very accurate navigation filter solution that dynamically evaluates the sensor inputs.” In GNSS-degraded environments, the Versa’s software alerts users that GNSS signals are not reliable, automatically filters out those measurements, and navigates on the basis of the other sensors, such as an IMU, a speedometer, an odometer, or a camera.
Locata’s system is completely independent of GNSS because it does not require atomic clocks. At its heart is the company’s TimeLoc technology, which generates network synchronization of less than a nanosecond, Gambale said. “TimeLoc,” Locata literature states, “synchronizes the co-located signals with other LocataLites as the signals are slewed until the single difference range between it and the other LocataLites is the geometric range. This internal correction process is accurate to millimeter level.” Applications of this system include indoor positioning for consumer devices such as mobile phones, industrial machine automation for warehousing and logistics, positioning first responders within buildings, and military applications in GPS-jammed environments.
Constellations and Timelines
How long will it take to develop and/or complete these complementary PNT systems?
Xona is a start-up, and its timeline will depend on its success with investors.“We have basically locked down our signal and system architecture. Now, it’s a matter of building out the ground segment and launching satellites,” Jaramillo said.
Xona’s current target is to launch its first satellites into operation by the beginning of 2025 and to achieve full operational capability by 2027. The company will roll out PULSAR in phases. “In our first phase, we’re going to offer timing services and GNSS augmentation that only require one satellite in view,” Jaramillo said. “Then, as we roll out to phase two, we’ll be able to start to offer positioning services in mid-latitudes with multiple satellites in view. Phase three will include high-performance PNT and enhancements globally.”
Satelles’ STL is already on Iridium’s 66 active satellites, which are all relatively new, having been launched between 2016 and 2018, and cover the entire globe constantly. STL’s signal and capability are flexible, O’Connor said.
Orolia Defense & Security is now evaluating UWB computer technology from different vendors and integrating it in the Versa’s software. “We will probably begin performing full field tests in the first quarter of 2024,” Payne said.
Locata’s mission, Gambale said, “is to deliver technology advances which enable complete, independent sovereign control over PNT for companies, critical infrastructure systems, and in the future – entire nations. It’s designed for the many entities and nations which do not have – and can never afford – their own constellations”.
“Our business model,” Gambale added, “is based on enabling others – from companies through to nations – to develop their systems and products based upon our core technology developments. We do not dictate how our technology will be deployed. Locata’s technology can be available to any suitably qualified partner, to fashion our core developments for their own use.”
The Launch of a Falcon 9 rocket carrying Xona satellites. (Image: Xona Space Systems)
Business Model
It is challenging for any new commercial entrant in the PNT field to challenge a free global service, such as GPS. While all these new services are the opposite of GPS, which is a gift from U.S. taxpayers to the world, their business models vary somewhat.
“We are targeting both mass market applications and high-performance ones,” Jaramillo said. “For the mass market applications, our business model includes a lifetime fee: a customer pays a fee one time, and the service works for the life of the device. For higher performance applications that have more capabilities associated with them, there will be different tiers, each with different services.”
These will include an integrity service that will verify that the signal has a certain level of performance thresholds, for use in critical applications. “If it drops below certain performance thresholds,” Jaramillo said, “we will flag that to the device so that it knows that, even though it is receiving a signal, it should not continue to use it due to signal degradation.”
Receivers and Chipsets
Predictably, these new ventures have spawned a web of alliances.
The success of both Xona and Satelles will hinge in part on the availability of receivers for their signals. To manufacture them, Xona is “in discussions with just about every tier one manufacturer out there,” Jaramillo said. “We have a strong relationship with Hexagon | NovAtel. They have been supportive of us for a long time now and are very advanced in their development and support for our signals.” Additionally, Xona designed its signals “so that most receivers can support them with just a firmware upgrade.”
Satelles is also working with partners, including Adtran (through their Oscilloquartz product line), Jackson Labs (now VIAVI Solutions), and Orolia (now Safran Trusted 4D). “Companies like that provide the solutions that are favored by critical infrastructure providers today,” O’Connor said. “They ultimately integrate our STL capability into their solutions. They can use our reference designs or create their own custom designs based on our reference designs.”
Satelles uses a different process to take measurements of the STL satellite signals than legacy GNSS. “It’s not a single chip that’s measuring both satellites, it’s ultimately two chips that are making those measurements,” O’Connor explained. “Then, we leave it to our partners to determine how to perform the position calculation and the integration of those signals. It can be integrated loosely or tightly.”
Markets and Applications
The target markets and applications for these new PNT services also vary.
The markets in which Satelles has the highest adoption rates are data centers, stock exchanges and 5G networks, said O’Connor. He pointed out that 5G networks need about five to 10 times more nodes to cover a geographic area than 4G networks.
“GNSS has been used for years to time 4G networks, but most 5G network sites — such as femtocells and picocells — are indoors or in places where GNSS is challenged. We deliver that timing service indoors, outdoors, everywhere.” Generally, an STL-only solution is best suited for timing, O’Connor said. “It will do timing at about 100 ns, depending on what kind of oscillator is being used and the exact configuration of the product.”
Orolia provides precise position, timing, and situational awareness for different applications. “Our systems can be used for ground, air and sea-based applications,” Payne said. “At Orolia Defense and Security we market to the U.S. government, defense organizations and contractors.” Beyond those arenas, however, its systems can be used “anywhere accurate position and/or timing is needed.”
Versa PNT. (Image: Safran Federal Systems)
The Role of Simulation
Simulation plays an important role in the development of new PNT systems. “Before the Xona constellation or any other emerging constellation has deployed any satellites, simulation is the only way for any potential end-user or receiver OEM to assess its benefits,” Ackermann said. “Before you can do live sky testing, a key part of enabling investment decisions — both for the end users as well as the receiver manufacturers, and everybody else — is to establish the benefits of an additional signal through simulation.”
Then, new receivers must be validated to ensure they perform as intended. “The best way to do that is with a simulator,” Jaramillo said. “Spirent works with two levels of customers: first, the receiver manufacturers, then all the application vendors that use those receivers.”
Spirent Communications did that for Xona’s system using its new SimXona simulator. “First, we did in-depth validation ourselves,” Ackermann said. “Then, we worked in a close partnership with Xona for them to certify that against their own developments. So, we followed a proven development approach. It’s just that, in this case, the signal comes out of a LEO.” Spirent Communications’ sister company Spirent Federal Systems also provided support to Xona, said Crampton.
Validation and Adoption
The European Commission’s Joint Research Centre in Ispra, Italy, recently conducted an eight-month test campaign to assess the performance of alternative PNT (A-PNT) demonstration platforms, including Satelles and Locata. According to the final report, released in March 2023, the demonstrations “showcased precise and robust timing and positioning services, in indoor and outdoor environments. [T]ime transfer technologies over different means were demonstrated, including over the air (OTA), fiber, and wired channels. The results … showed that all A-PNT platforms under evaluation demonstrated performances in compliance with the requirements set.”
Satelles has also been working with the U.S. National Institute of Standards and Technology (NIST) to evaluate its system. “They have subjected STL to rigorous third-party, hands-off technology evaluations,” O’Connor said. “They confirmed the timing accuracy specifications to UTC and validated the operational characteristics of STL, such as the resilience in the absence of GNSS, the ability to receive the signal indoors, and having global availability.”
The industry is now focused on adoption. “All the providers of these capabilities ultimately need adoption in industry to remain active and viable,” O’Connor said.
With the recent completion of two new GNSS constellations, the growth in the number and variety of augmentation services, and the development and deployment of complementary PNT products and services, the geospatial industry is at an inflection point.
Max Weber famously described how bureaucratic inertia often leads formal organizations, such as government agencies, to devise new justifications for themselves after they have outlived their original purpose. That is certainly not the case for the U.S. Space Force, which is in its infancy and is responsible for key missions, including operating the Global Positioning System that it took over from the United States Air Force about two years ago.
However, bureaucratic inertia can also refer to the tendency of organizations to continue to pursue projects or approaches that may no longer be the best match for their goals, missions, or budgets. A recent, congressionally-mandated report by the United States Government Accountability Office (GAO) — Report to Congressional Committees, GPS MODERNIZATION: Space Force Should Reassess Requirements for Satellites and Handheld Devices, issued in June — questions the Space Force’s approach to modernizing GPS with a more jam-resistant, military-specific signal known as M-code.
In 2005, the Air Force launched the first GPS satellite capable of broadcasting the M-code signal, which is at the core of a multi-billion-dollar modernization and sustainment effort. Yet, 18 years later, widespread adoption of the technology is still hampered by delays in upgrading GPS ground and user equipment. Approximately 700 types of weapon systems — including ground vehicles, ships and aircraft — will ultimately require M-code-capable user equipment.
Providing M-code requires the cooperation of GPS’ ground, space and user equipment segments. Regarding the first one, the report states: “In 2022, Space Force further delayed delivery of the ground control segment due to development challenges. This delay pushes delivery until December 2023 at a minimum. Space Force officials have not finalized a new schedule and acknowledged that remaining risks could lead to additional delays.”
Regarding the space segment, it states: “Space Force met its approved requirement for 24 M-code-capable satellites on orbit but determined that it needs at least three more to meet certain user requirements for accuracy. Building and maintaining this larger constellation presents a challenge. GAO’s analysis indicates it is not likely that 27 satellites will be available on a consistent basis over the next decade.”
Finally, regarding the user segment, it notes that development of the Military GPS User Equipment (MGUE) Increment 1 has progressed “to the point where the military departments are ready to commence activities in support of testing and fielding it on the lead weapon systems.” However, it cautions that “[d]elays and unexpected challenges could affect the fielding of capability for some systems.”
GAO’s report recommends that the United States Department of Defense (DOD) assess the number of GPS satellites necessary to meet operational needs, and either develop a sound business case for the M-code-capable Increment 2 handheld, or not initiate the effort. The DOD concurred with both recommendations.
“Who Runs GPS?”, the special feature in our February 2023 issue, which detailed the structure of this vast enterprise, listed an executive committee, a coordination office, an oversight council, two Space Force commands, and, as partners, several federal departments and agencies. Has this complex structure become too diffuse to make tough decisions?
An exclusive interview with Nunzio Gambale, Co-Founder, President and CEO, Locata. For more exclusive interviews from this cover story, click here.
Locata dish antenna pointed to the European Union’s Joint Research Center in Ispra, Italy, 44 km away, just under the setting sun. The Yagi antenna above is pointed to a cell tower in Como and used to connect the system for remote control and data logging. (Image: Locata)
In brief, how does Locata work? What are the key concepts?
Almost everything you know about GNSS pretty much applies to Locata. We are an extremely close cousin. We use trilateration; in other words, we use time of flight from transmitter to receiver as our pseudorange. We work with both code and carrier solutions. We transmit CDMA Gold Codes, chipped at 10MHz. Everything in the algorithms that you use for GNSS is pretty much the same, and so it feels extremely familiar to any GNSS engineer. We have an interface control document (ICD) that describes our over-the-air interface, exactly as GPS or Galileo does. That’s available to our integration partners. So, the similarities are incredibly close.
The main place where we diverge greatly from GNSS is in the use of atomic clocks. One of the three fundamentals of GNSS is that all your transmitters have to be synchronized for the trilateration to work at your receiver. Syncing the satellites requires a master clock — in the case of GPS, with a redundant feed from the U.S. Naval Observatory — and a very complex ground infrastructure. Our system requires neither atomic clocks nor a control segment. Importantly, just like GNSS, our satellites do not communicate with each other. LocataLites, our version of the satellites, only broadcast a signal, thereby enabling an unlimited number of receivers to use our devices.
Locata’s core inventive step was the Time Lock loop invented by my partner, David Small. Any engineer is familiar with a frequency lock loop or a phase lock loop, which allows you to align either phase and frequency in a very intelligent way by looking at the offsets and then moving the two components into alignment. That’s what we do with time. It is a fundamental difference from requiring clocks, which all drift and are very difficult to synchronize, as the complexity and cost of the ground segment testifies. Many people get confused because they believe that super accurate atomic clocks will all give you the same time. Clearly, that’s not the case, because they drift relative to each other. However, satellite navigation requires keeping the clocks synchronized.
Our system is a synchronization technology that does not require atomic clocks. We synchronize our transmitters to incredible levels, better than what’s generally available from the synchronization of atomic clocks. That allows us to do everything that a GNSS does in our coverage area.
We’ve invented the Time Lock loop. Dave has more than 170 granted patents on this and on multipath mitigation. Nobody else has done this or can do it. All other high-precision systems require external correction systems. Our carrier solution is a single point solution. We don’t need any external corrections provided from reference stations, or communication links between our devices. Our system is, and remains, synchronous to the picosecond level, which allows us to do carrier-phase positioning without corrections. That’s utterly unique.
As the old joke goes, a person with a watch always knows what time it is, a person with two watches never does.
That’s one of my favorite quotations for people who don’t understand this.
It has been said that the only replacement for a GNSS is another GNSS.
And my favorite riposte to that is “the solution to satellite-based problems is not more satellites”!
We now have four GNSS but they have some common failure points. What’s your view of the debate about GNSS vulnerabilities and the need for complementary PNT? How does Locata fit into it?
One of our main drivers is the knowledge that all those global systems are fundamentally military based. Galileo tries to make itself an exception, I know, but the core motivation for nations to put up these kinds of very complex and expensive systems is for full global military purposes. Locata has probably been working on this complementary PNT technology longer than just about anybody else. We began in 1995, with the problem that GNSS does not work indoors. That was the first light bulb moment for us about the issues with GNSS not being able to serve all the potential future applications. So, we’ve been at this a long time. Global systems absolutely have their place, but there are many applications now and in the future that do not require them.
Where did your realization lead you?
We started to look at ways of filling in the holes that we saw in GNSS. That led us to the two unique capabilities that we’ve currently developed and commercialized: the synchronization of transmitters, which is the heart of all radio-based positioning, and, because we work in terrestrial systems, how to deal with multipath. Those are the core new enabling capabilities that Locata brings to the industry today.
There are mountains of reports detailing the vulnerabilities of GNSS, starting with the 2001 report by the John A. Volpe National Transportation Systems Center for the U.S. Department of Transportation right through the very latest one from the European Commission’s Joint Research Center (JRC) in Ispra, Italy. All those myriad reports document the vulnerabilities of GNSS and the dire dependencies they create. These dependencies mean that the more than 95% of applications that are civilian are vulnerable, if and when the military have to do what they have to do with their systems in a military conflict. So, for us, it’s all about giving civilians and nations sovereignty, and national-level resiliency, firstly to critical infrastructure systems.
That’s what we set out to demonstrate with our long-range deployments at the JRC. Our systems must be able to be scaled, in time, from purely local up to national systems. Because Locata’s focus must be on civilian systems and sovereignty that can be delivered back to nations, with systems that are independent from the military ones. We’re not trying to replace global systems, at least for now.
GNSS provide positioning, navigation and timing (PNT) at the global level. You have addressed the global level. Let’s talk now about PNT.
P, N and T are all important. Timing, of course, is GNSS’s hidden component for most people, but it is critical to many applications. Anybody who wants to see the work that Locata has put in over the last couple of decades to bring new capabilities to the industry should look at the JRC’s report, which is the very latest and probably one of the most comprehensive reports that’s been produced in the past decade. The European engineers were incredibly thorough in the way they tested all candidate systems, including Locata. If I could speak proudly about our team’s achievements, Locata’s P, N and T results presented in that report speak for themselves. Locata’s technology was demonstrated to perform in every environment the JRC engineers requested, including indoors.
That’s one of the functions that we absolutely want to bring to market. Our systems don’t stop at the wall, they can continue to work indoors, you can propagate positioning and timing from outside to inside. The performance that was measured independently by the researchers showed that indoors we were delivering centimeter-level positioning in brutal multipath conditions, as well as outdoors.
Locata is doing superb work with some of the most complex automation systems in the world now, which unfortunately we’re constrained from discussing because of nondisclosure agreements.
Say more about the role of synchronization.
Locata dish antenna pointed to the EU’s Joint Research Centre, 8km away across Lake Maggiore in Northern Italy. This antenna was an intermediate node during the EU’s independent testing of Locata’s picosecond-level time transfer over a 105km distance. (Image: Locata)
Synchronization is the heart and soul of everything that we do with radio positioning. Clearly, Locata has been able to do high-precision synchronization without atomic clocks, at an almost unbelievable level, for many years. The first system that we deployed is at the White Sands Missile Range in New Mexico, where the U.S. Air Force jams GNSS over a vast area, yet Locata continues to deliver centimeter-level positioning and picosecond-level synchronization. That is unprecedented and cannot be done with satellite-based systems. The European JRC engineers measured our synchronization at the picosecond level, cascaded 8 times from one transmitter to another over more than 105 km. This is an extremely difficult thing to do, given that you’re trying to remove the propagation and component delays introduced by each intermediate transmitter. Our synchronization was measured to basically deliver timing equivalent to fiber, but over the air, using RF. I don’t believe any other company can demonstrate that.
This development allows us to start deploying systems commercially, which we are doing today via integration partners. In the future, as we miniaturize, bring the price down and scale our capabilities into other frequencies and at power levels that are commensurate to national-level systems, we intend to cover entire nations with our capability, and deliver not just what’s required today, but what’s required for future apps.
One of the few things that we don’t agree with in the JRC tender and report is that they set the PNT “performance bar” at 100 meters and one microsecond. For 80% or 90% of serious applications — especially for autonomous systems, and any applications that need fine control, including surveying — 100 meters is completely unusable, apart from maybe intercontinental aviation systems. Locata delivers the picoseconds and the centimeters that future applications require. As we commercialize further, we will deploy more and more systems that demonstrate that capability.
So, you could not use Locata to navigate on transoceanic flights.
No, we’re clearly not focused on doing that. We’re a business, and we’re working on the applications for which we see the most civilian, commercial value. Nevertheless, the U.S. Air Force does use Locata and so we’re in discussions with other militaries now. Clearly, we can cover very large areas — say, around airports and military bases — and continue to work at very precise levels, both for timing and positioning, in anything up to completely denied environments. It’s a proven fact that our systems are being used on a regular basis where GNSS has been jammed, and Locata is the truth for those tests. You cannot get a more convincing demonstration of non-GNSS-based PNT than the U.S. Air Force’s use of Locata at White Sands.
What about the application with by far the greatest number of users, which is cell phones?
Absolutely, without question, we believe Locata will eventually be used in mobile phone systems, especially for indoor positioning. Locata’s receivers today look very much like the 1990s version of GNSS receivers. However, there are zero engineering roadblocks to scaling or reducing our devices to a chipset. It’s a chicken and egg business development problem: you can’t get to mobile phone-type scale until you’ve engaged and are working with companies in that industry. Part of the reason we worked so diligently to demonstrate our new capabilities in the JRC tests, is that many of the claims that we’ve made about centimeters and picoseconds have been fairly unbelievable in terms of the capabilities that were previously publicly demonstrated. Our participation in the JRC tests was motivated in many ways by being able to point to the 140-page report produced by the engineers in Europe, and prove beyond question that we actually do what we claim.
We have now begun discussions with companies in the cell phone industry. Technically there’s no question that in the future we can reduce our receivers, firstly, and then our transmitters, into either chipsets or into IP cores that can be dropped into other companies’ chips. That’s a work in progress. The engineering to take this down to a chipset is now mostly constrained by not yet conducting business development in that market segment. However, we are working toward that, and are in discussion with some of the big players in that industry.
It sounds like you are working with different industries at different scales.
Locata engineers set up the distinctive VRay Orb antenna for an indoor cm-level positioning demo in the Joint Research Centre’s all-metal Workshop Building. (Image: Locata)
Yes, and the markets we are in today are delineated by the current form-factor of our devices. Today, our devices are similar to the GNSS receivers that you would have seen back in the 90s. Because we’re FPGA-based and not chip-based our devices tend to be relatively large, power-hungry and relatively expensive. That’s why we’re working into markets where that is not a roadblock. Our main partners today have massive problems that they need to solve, specifically for industrial automation applications. We’re working with some extremely large global businesses in some of the most complex and demanding automation applications in the world. It frustrates me enormously that we cannot publicize those yet because we’re under commercial non-disclosures. Therefore, we remain tight lipped about our current installations.
However, those in Locata’s inner circle know that we’re working with some of the most advanced automation capabilities in the world. I am very eager to show the world what we’re doing. And we soon will.
Obviously, the U.S. Air Force work that we’ve been doing for eight years is publicly visible. Our team right now is working with them on an extension of that contract. As I said, we’re also in discussions with some other nations and we look forward to being able to publicly disclose some of our applications in the future. For now, unfortunately, I need to remain tight lipped and just keep working on the installations that we have underway. Hopefully, soon, when these things become visible in public, I’ll finally be able to promote them.
Is sensor fusion relevant to Locata for certain applications or will it always be a standalone system?
Locata does not necessarily need to be standalone. Our partners, who are the experts in their machines and applications, are responsible for integrating Locata with other sensors, such as inertial units or cameras or lidar-based systems that may already be on their machines, just like they would with any GNSS system.
Our business model is working with partners. So, it’s a business-to-business model, whereby we partner with companies that have a problem they need to solve in their products. We work with their engineers to integrate our system — just like GNSS engineers work with their engineering partners to integrate receivers into systems of systems. That is generally what is required in many of the applications in which we’re used for autonomy.
One of the great features of our technology is that we can guarantee our partners, without fail, exactly how many Locata transmitters will be in view for their application in any area or environment. We can over-determine the solution on a site so that if, say, you get lightning strikes or power outages, the system can continue to function at the level that you require. That’s never possible with satellites, because you never know where your receivers will be relative to obstructions and the DOPs of the satellites. So, our system can be standalone. But in 90% of the applications in which we are working it is integrated into a system of systems, just like GNSS is.
What, if any, is the role of simulation with respect to your system?
We are currently in discussions with a major simulation company for integration into their software suite. They see enough demand now from enough players to be working with our integration. I can’t name them because it’s not a commercial system yet. However, they have our data and ICD, and they are working with our engineers to incorporate Locata simulations into their product offering.
Is there anything else that you would like to add?
Unlike GNSS or LEO-based systems, which take a long time to change, we can customize and modify our systems very quickly. Our next generation systems are frequency-flexible: we can put our systems into any radio band from 70 MHz, up through all the phone bands, the radio navigation bands for aviation, emergency services bands, right up to the 6 GHz WiFi bands. Those devices are in prototype right now. We can very quickly modify, update and upgrade our system, which allows us to have a very rapid development cycle that satellite-based systems will never have.
For instance, the U.S. Air Force’s NTS-3 Vanguard satellite that has been coming for several years will soon demonstrate new capabilities. Yet it will still take decades to deploy them. LEO satellites, which are getting an enormous amount of attention today, still have major constraints in terms of upgrades, modification, and or the deployment of new capabilities. Very few people in the industry talk about the replenishment of satellites which these massive constellations will need because in LEO orbits they will naturally deorbit every four to six years or so.
That means that there’s a huge requirement to continually replace LEO satellites in space, which will obviously require an enormous cost, and complex engineering effort. When you have several thousand satellites, in different planar orbits, deciding where you’re going to place replacement satellites for the many that are failing, is going to be an enormous headache for all these companies that are trying to put LEOs in space. Locata doesn’t have any of these issues. As we move forward, we will miniaturize, go to chipsets and software-defined radio capabilities. We can evolve at a rate that space-based systems can’t even begin to approach. Given that we live in an age of rapidly evolving threats and vulnerabilities, our ability to rapidly react to these challenges is, we believe, a valuable addition to the tool-box of PNT capabilities the world requires.
Thanks for allowing us this opportunity, Matteo, to speak to your large and expert audience.
An exclusive interview with Dr. Michael O’Connor, CEO, Satelles. For more exclusive interviews from this cover story, click here.
How many Iridium satellites carry your system?
Mike O’Connor
Iridium has 66 active satellites. There are also several spares on orbit. The satellites were all launched between 2016 and 2018, so they are all relatively new. They cover the entire globe, 24 hours a day, seven days a week, so they have universal coverage.
How will your constellation grow?
Today, our Satellite Time and Location (STL) service is offered only over the Iridium satellites. There’s nothing else that we’re discussing publicly. It could expand over time to other satellites. The signal and the capability are flexible. In terms of how Iridium could change, that’s more for Iridium to discuss than us.
Who makes chipsets that can use your system? And how does that work?
We work with partners. For example, with Adtran (through their Oscilloquartz product line), Jackson Labs (now VIAVI Solutions), Orolia (now Safran Trusted 4D). Companies like that provide the solutions that are favored by critical infrastructure providers today. We provide them either reference designs or effectively referenced designs. They ultimately integrate our STL capability into their solutions. We help them to do that. They can use our reference designs or create their own custom designs based on our reference designs. So, that’s the model that we use.
Is the STL receiver on top of a traditional GNSS receiver and passing certain data to it?
STL is used in two ways. In some cases, users are trying to do positioning or timing in an environment where GNSS signals will not reach, such as indoors, or are otherwise unavailable. In those cases, it wouldn’t be overlaid with GNSS, it would just be a standalone solution.
In many other cases, the goal is having a solution that is resilient to an outage, interference, jamming, spoofing, those sorts of things. In that case, the receiver card that might be provided by one of our partner companies would have both GNSS and STL capabilities and would take the best of both worlds. If GPS is jammed or there’s interference, then the STL signal alone would be sufficient to do PNT. However, whenever both signals are available and can be authenticated, then it would use both and leverage the benefits of having two systems.
Does the location calculation take place in a GNSS chip or separately in the STL?
The chain to take measurements of the STL satellite signals is different. It’s not a single chip that’s measuring both satellites, it’s ultimately two chips that are making those measurements. Then how the position calculation and the integration of those signals is done is left to our partners. In some cases, it is proprietary to the partners that are doing that integration work. It can be integrated loosely or tightly.
When it’s just the STL chip, is that usually for timing purposes, or both timing and location?
Generally, an STL-only solution is best suited for timing. It’ll do timing at about 100 ns, depending on what kind of oscillator is being used and the exact configuration of the product.
What positional accuracies can you achieve?
Generally, in the 10 m to 20 m range, depending on the product configuration.
Most of the correction services refer to variables that are not relevant to your system.
That’s right. There are other techniques, such as integrating with other sensors, that can improve the accuracy. The primary uses for STL today are in delivering timing in environments where GNSS is not able to do so today, such as for national critical infrastructure. That’s been our commercial focus as a company.
Who currently uses the STL receivers? Which markets are you targeting first?
Most of our users are in the data center space. Stock exchanges around the world are also using our service as a source of resiliency, and now wireless infrastructure. So, think 5G infrastructure. As 5G networks are rolling out, they need about five to ten times more nodes to cover a geographic area than 4G networks. GNSS has been used for years to time 4G networks, but most 5G network sites — such as femtocells and picocells — are indoors or in places where GNSS is challenged. We deliver that timing service indoors, outdoors, everywhere. So, those are the three commercial markets where we have the highest adoption rates.
You still have plenty of room for expansion in that market before you must start thinking about expanding into other areas.
Yes, there’s plenty of room for expansion into those markets, so I wouldn’t say that they’re fully saturated. We are also looking into other opportunities. We’ve seen interest in the energy area. I think the industry is a little bit slower moving, but the need is ubiquitous, right? We all recognize that a black swan event in our society would really represent a bad day and we want to avoid that.
There are several companies across the industry that are trying to solve that important problem. Everyone involved in critical infrastructure that requires a timing reference — which is anything that is associated with a network activity — should have an alternative or augmentation to GNSS as a timing source. It’s great that we’re seeing tailwinds from the U.S. Government, from the European Union, and from others to try to encourage that adoption. However, there’s still a long way to go before we really feel that that’s been sufficiently covered.
What, if any, have been the major developments in the past year or so?
One of the most interesting things that has happened over the last year and a half has to do with our capability regarding STL. We’ve been demonstrating more publicly, and with more independent authorities, the capabilities, resiliency, and operational characteristics of our service.
For example, the JRC study.
It started with the U.S. Department of Transportation (DOT) a couple years ago, but there’s also been some work done by the Department of Homeland Security and with the National Institute of Standards and Technology (NIST). We’ve been working directly with NIST to do some validations, as well as with UK and European organizations. They have subjected STL to rigorous third-party, hands-off technology evaluations. They confirmed the timing accuracy specifications to UTC and validated the operational characteristics of STL, such as the resilience in the absence of GNSS, the ability to receive the signal indoors, and having global availability.
We’re delighted to see the third-party operational evaluation of things that we’ve known all along but are now being evaluated and confirmed by these government sources. Beyond that, of course, there are always going to be technology advancements, both with our company and with other companies.
The real focus of industry right now is on adoption. All the providers of these capabilities ultimately need adoption in industry to remain active and viable. These are good people trying to do the right thing to protect our society. There are many great technology solutions out there to do it. Hopefully, many of these solutions are adopted in the near term. That’s what our focus has been. Our focus has not been on squeezing an extra five nanoseconds out of performance, although, of course, we’re always doing that. I think the important focus of industry should be driving adoption. There are solutions available today, including ours, that are ready to go and are being proven operationally in use.
Can you say more about the study by the European Commission’s Joint Research Centre (JRC)?
If you look at the summary, all these technologies that were demonstrated worked. Both the DOT report and the JRC report effectively summarize that there are multiple technologies out there today that are ready to go.
