031: GPS fördjupning GNSS utmaningar med NextNav

Varmt välkomna till ytterligare ett avsnitt av Mätpodden. Det här är det andra fördjupningsavsnittet om GPS, med en intervju på engelska som jag spelade in för det här specialavsnittet av Mätpodden.

Intervjun är inte så lång, knappt en halvtimme, och den är med NextNav, ett företag i San Francisco som utvecklar markbaserade och alternativa positioneringslösningar till GNSS-signaler.

Det handlar alltså om att använda sig av annat än enbart satellitsignaler för GNSS. Företagets vd förklarar mer om detta och målar upp en bild av problemen och utmaningarna med GNSS. Han har kanske en något annorlunda, eller mer problemorienterad, bild av GNSS.

Han har förstås också en alternativ lösning att erbjuda, men jag tror att det är ett bra perspektiv att ha med sig: vad som skulle kunna hända med GNSS, vilka risker som finns och vilka andra alternativa lösningar som finns där ute. Så lyssna på det.

Sedan hörs vi igen i nästa avsnitt. Innan jag spelar upp intervjun vill jag i sponsorsegmentet påminna om min egen kurs på landskaparen.se. Kanske känner du igen dig som anläggare.

Oavsett om du arbetar med mätning eller inte kanske du vill lära dig lite mer om ämnet. Du kanske redan har en mätstav och använder Geo, SkyMap Design eller någon annan mätprogramvara, men känner: ”Det var ingen som lärde mig det här.”

Det finns ingenstans där jag kan lära mig det ordentligt. Jag kan gå en kurs i Geo, BricsCAD, Topocad, Gemini eller något annat. Du kan lära dig en programvara, men var lär du dig teorin bakom? Hur fungerar allt egentligen?

Vad är en terrängmodell eller en maskinstyrningsmodell? Vad är en XML-fil eller en DWG-fil, och hur hanterar jag dem? Vad är ett koordinatsystem? Det tror jag att jag kan lära dig. Den första kursserien går i augusti.

Den består av fyra tvåtimmarslektioner, alternativt en heldag, där du kan lära dig de här sakerna. Jag kommer att ge extraordinär support, och du kommer att få ett oslagbart pris. Gå in på landskaparen.se och läs mer om min första kurs.

Mät och modell, steg ett. Nu fortsätter avsnittet.

If you could just introduce yourself a little bit and give us some background, and then go into the tangent you started talking about—that the world is a hostile place.

Yeah. I'm Ganesh Pattabiraman, co-founder and CEO of NextNav. We're a company based in Sunnyvale, California. Before I started NextNav, I was at Qualcomm, where I worked on putting GPS into cell phones and Qualcomm chipsets. That eventually made Qualcomm one of the largest providers of GPS chipsets worldwide.

I think the genesis of NextNav was really understanding the limitations and constraints of GPS. It's a space-based technology that is highly effective and has endured for thirty or forty years, but it has certain limitations. Fundamentally, those limitations appear in urban areas and indoor environments. There are also security risks because it is an unencrypted signal. The signal radiating from space has about the power of a thirty-watt light bulb, so it is vulnerable to jamming.

That led us to what we felt was a complementary system—one that provides GPS-equivalent capabilities in places where GPS doesn't work, as well as when GPS is absent. We provide three-dimensional positioning, navigation, and timing. By that, we mean that we're able to provide not only altitude capabilities, but also very precise horizontal positioning and timing when GPS is unavailable in indoor and urban environments.

That's the platform we've built. We have rolled out the first phase of the service in the US, providing altitude capabilities together with GPS-based X-Y positioning. We then expect to roll out the next phase, the TerraPoint service, which provides full three-dimensional positioning, navigation, and timing in GPS-challenged environments. We expect that to happen in the next few years.

If we start with the technology, how do you actually use the altitude data? I'm just thinking: can I use my iPhone, or a regular phone, to see my altitude? How does it work?

Yeah. GPS is space-based, and because the satellites are effectively in a single plane, you can't determine altitude precisely. To provide precise altitude—especially floor-level altitude, which is where we want to get for meaningful user interaction—we use barometric techniques.

As we all learned in high-school physics, pressure is inversely related to height. If we can measure the pressure, we can compute the height. To do that, we deploy a network around major urban markets. By combining pressure data from our network with the pressure measured by a phone—and most modern cell phones have barometric pressure sensors—we're able to determine the user's height very precisely.

In government tests run by the FCC in the US, we were able to determine height within three meters about ninety-four percent of the time. It was found to be the most precise system available.

It's really about repurposing sensor data that already exists on your phone but was primarily used for hiking. It was used to determine whether you had travelled thousands or tens of thousands of feet, or hundreds of meters. By applying differential techniques, we're able to tell you the meter-level separation between locations.

That has found very effective uses in the US. We launched it in partnership with one of the largest wireless operators in the country, AT&T, to provide three-dimensional situational awareness for police and fire services. Knowing where police officers and firefighters are inside a building is very important, so a commander can tell them where to go, what to stay away from, and so on.

That service is being used by AT&T and FirstNet, the US government network for first responders. It's also used for emergency nine-one-one calls. In the US, when there's an emergency, you have to geolocate the user in three-dimensional space and provide that information to the police and fire services so they can reach the person.

It is being used by Verizon Wireless, the largest wireless provider in the US, and by several other tier-one wireless operators. It has many applications in public safety, emergency calling, the Internet of Things, mass-market applications, and gaming. As the world becomes more three-dimensional, knowing where the user is in three-dimensional space is important for gaming experiences and metaverse-type applications. There are many different applications that benefit from this.

Interesting. If we take a step back to GNSS, what are the main problems with interference and other vulnerabilities? I've been talking about natural forces, such as solar flares, as well as military operations. How would you describe the problems?

I think there are multiple challenges. GNSS was designed with an entirely different application in mind: allowing the military to navigate worldwide. It was later adopted for many other applications.

The first challenge is that it's a space-based signal. Right off the bat, as you pointed out, it's vulnerable to solar flares and other naturally occurring solar activity. Secondly, it radiates a signal of about thirty watts—the power of a light bulb in your bedroom—from space. The signal travels thousands of kilometers down to Earth, so it is very easy to jam.

I can transmit a signal from another device on the ground and essentially make the space-based signal impossible to receive. I can also spoof it. Because GPS is not encrypted, you can fake the information that the GPS satellites send. It is therefore very easy either to make GPS unavailable through jamming or to spoof the signal and make it look as though you are somewhere else.

You can do that very inexpensively. You can buy a GPS jammer for one hundred or one hundred and fifty dollars, plug it into the lighter socket in your truck, and disrupt GPS over a large area around you. It's relatively easy to do.

GPS also has physical limitations. Because it is a space-based signal, it doesn't work well in the places where we live, work, and play—indoors and in urban areas—and it cannot tell you precisely what altitude you're at. There are a number of limitations that exist simply because of the nature of GPS. It is an important part of the overall geolocation ecosystem, but it certainly needs help in some of these key areas.

How common would you say jamming and spoofing are in real life? Do you have any examples?

Yeah. I would say it used to be much rarer. It has been happening for perhaps half a dozen years or so, but its frequency has now increased.

Previously, it happened mainly in regions of conflict in the Middle East—for instance, in places such as Iran, where GPS was spoofed to restrict or interfere with military operations. In Syria and elsewhere, GPS was jammed to impair drone operations so that people could not be located. There was also a theory that US Navy personnel who strayed into Iranian waters had been misdirected by GPS spoofing.

In the last year or two, especially in Europe, it has become much more prevalent. A great deal of our critical infrastructure—agriculture, the electrical grid, and telecommunications equipment, for example—relies on GPS for timing. Most people don't think about that. To keep networks synchronized, even financial exchanges require precise timestamps.

By spoofing or jamming GPS, you can affect critical-infrastructure operations. You could disrupt the electrical grid by jamming GPS, leaving substations without timing, or disrupt data centers and similar systems.

Unfortunately, in the Russia-Ukraine conflict, this has become one of the weapons of choice. GPS is routinely jammed by Russia in Eastern Europe. We have seen maps showing disruption across large parts of Ukraine, Poland, Finland, and the Baltic region. It is easy to jam, and you are not formally declaring war on another country, but you can still disrupt infrastructure very effectively.

It reached a point where, in March two thousand twenty-two, the European Union Aviation Safety Agency issued guidance warning aircraft operators in Finland and the Kaliningrad region not to rely on GPS as their sole source of navigation because it had become unreliable. It has certainly become very prominent in Europe, and the risk can spread because it is relatively easy to jam critical infrastructure using radio-frequency technology from some distance away.

Interesting. I'm looking at the map on gpsjam.org, and you can see quite large regions that are red, indicating jamming or at least some kind of interference.

You mentioned the timing aspect. Could you give us a basic primer on the timing side of GNSS and how it's used in infrastructure? I've only just started reading about it, because in my field I've always thought about GPS in terms of positional accuracy. How is timing used?

We all use GPS, and it has become very popular for positioning and navigation. That's how most of us think about it. Fundamentally, though, GPS is actually a timing network. All GPS satellites transmit very precisely clocked signals and a known timing pulse. You intersect the signals from multiple satellites to determine your location. That's basic high-school geometry.

Timing is therefore one of the key services GPS provides. The big benefits were that it was very precise and free. Critical-infrastructure providers—including those in agriculture, telecommunications, and the electrical grid—needed timing that was distributed globally or nationally. It was easy to install a GPS receiver and feed that timing into their equipment.

In telecommunications, for instance, base stations are synchronized using GPS. If they aren't synchronized, you lose capacity or drop calls because the base stations are operating on different timescales. That's one simple way to think about it.

The electrical grid is another example. Different electrical substations transfer power between them using phasors, and they all need a common sense of timing across the network. If they don't have it, transferring power from one substation to another can create a mismatch and lead to outages.

Financial transactions also need timestamps. You need to know when money was withdrawn or deposited, and when stock trades took place. Imagine if a transaction were timestamped a day earlier or a day in the future. Think about the amount of chaos that could cause in a financial network.

All of those applications rely on GPS timing. Because the signal is not encrypted and can be jammed, someone could pull up a truck outside the New York Stock Exchange, activate a jammer, and affect the timestamps applied to different transactions. You can imagine how that could disrupt the financial operations of a market or even a country.

Those are some of the risks. They are well-known and well-understood risks from a timing perspective, quite apart from aircraft, train, or boat navigation, which relies on GPS to get from one place to another.

How sensitive is the timing issue? Do we have real cases where infrastructure has been affected, perhaps in war zones? Is this theoretical, or have we actually seen an electrical grid go down because someone spoofed or jammed the signal?

There are several examples that have emerged in recent years involving GPS signals being jammed or spoofed. In the US, there have been incidents at electrical substations where operations may have been affected. It was not completely clear what the source was, but there was a belief that timing signals had been disrupted.

The classic examples are the ones I mentioned in Europe, where aviation authorities warned that GPS had become unreliable. In the US, there were also two incidents of jamming around Denver and Dallas airports in October two thousand twenty-two. GPS was disrupted for roughly twenty-four to thirty-six hours, although the source remained unclear. Aircraft operations at Dallas airport were reportedly affected for nearly thirty-six hours.

These examples are becoming more frequent than we would like. As more people become aware of these vulnerabilities, the risk increases. There was another example, I believe in Germany, where someone spoofed GPS around a Tesla while it was driving and caused it to believe it was on the correct side of the road when it was not.

Unfortunately, there are many examples showing that GPS jamming and spoofing have become much more common.

Yeah. Interesting. It sounds like a big problem. What is your solution, and how can we mitigate these risks?

The good news is that governments around the world have started to recognize this vulnerability and take action—at government speed, I would say, but they are taking action.

Since around two thousand seventeen, the US government, on both the military and civilian sides, has taken concrete steps toward developing what we call alternative PNT: alternative positioning, navigation, and timing systems that can address the risk.

In two thousand twenty, the US government conducted a study of alternative PNT technologies. It looked at ten or eleven different technologies and evaluated their performance. The European Commission later studied seven different alternative PNT technologies to understand what alternatives to GPS exist and how they could be used.

The good news is that governments are beginning to recognize the problem, and technologies like ours are available. We haven't talked much about our TerraPoint solution. Essentially, we deploy terrestrial, GPS-like transmitters on the ground and transmit a signal similar to a GNSS signal. More recently, we have been able to combine that with cellular signals to provide resilient positioning, navigation, and timing.

We can deliver positioning, navigation, and timing in urban areas and operate independently of GPS. Our signals are encrypted, and we can tell you what height you're at. Systems like ours provide a genuinely complementary service: they work indoors and in three-dimensional urban environments while also overcoming some of the security vulnerabilities of GPS.

The challenging part is how to address the entire economy. GPS and other GNSS systems, including Galileo, affect a large part of the economy: agriculture, telecommunications, aviation, and transportation. An approach that addresses those vulnerabilities in specific markets and applications is therefore important.

The US government is starting with specific industries and trying to build resilience into them. We expect the European Commission to take a similar approach. It is also important to recognize that multiple solutions will be needed.

Governments need to support those solutions because alternative PNT technologies are essentially an insurance policy competing against a free primary service. GPS and GNSS are free. That creates a market anomaly that must be overcome if alternative PNT technologies are going to complement them.

The US government, for example, recognizes this. Funding is being provided to develop alternative PNT systems that can complement GPS or GNSS while minimizing the cost to critical-infrastructure providers. Grants can help ensure those providers do not have to bear the entire cost and can reduce those points of friction.

How would these alternative technologies respond to the same kinds of threats—spoofing, jamming, and natural forces such as major solar flares? I'm thinking very broadly because I don't know the details. Are they radio-frequency signals that could be affected by the same things, or how does that work?

That's a good question. I can speak for our system, the NextNav TerraPoint system. Fundamentally, we're a terrestrial system, so we're not as affected by space-based events such as solar flares.

Secondly, because our signal is terrestrial, it is about one hundred thousand times stronger than GPS, so it is very difficult to jam. Our signals are encrypted, so they cannot easily be spoofed, and all our transmitters have authentication schemes built in. There is a modern security architecture built into the system.

One thing to keep in mind is that GPS is a nineteen-sixties technology. Many modern cybersecurity and encryption technologies were not available when it was developed. That is changing with newer satellite constellations, but it is not true of the signals most of us predominantly use.

Our system was developed during the last ten years, so we were able to take advantage of modern cryptographic and security systems. That makes it much harder to fake the information. The information payload is encrypted, and the network is authenticated, so you know you're communicating with a trusted transmitter rather than a rogue one.

Our signal is also so much stronger than GPS that, if someone tried to jam it in an urban area, you would probably be able to locate the jammer because it would need to transmit a signal stronger than ours.

We also have redundancy. At a typical point in the network, you can see between six and eight of our transmitters. If one or two are jammed, the others can still be used. We can now also take advantage of LTE signals in addition to our own network.

To dominate the signal, you would have to take out all the cellular base stations in the area, which is very difficult. It can happen, but at that point you're essentially in a state of war and the entire network in the area has been taken down.

Security is about adding more and more layers of protection, and we believe we have some of the best layers. The system is not one hundred percent bulletproof, but it significantly raises the hurdles someone would have to overcome to disrupt the signal.

Fascinating. I know we're running short on time, but could you tell us who would be a natural fit for TerraPoint from a customer perspective? Do you have use cases, or examples of who's using it at a larger scale? Perhaps you could say a little more about TerraPoint and NextNav before we end the discussion.

Yeah. As I mentioned, the first generation of our services is currently being used by first responders and nine-one-one callers.

On the TerraPoint side, many critical-infrastructure providers can benefit from our timing capabilities, including telecommunications users, data centers, and electrical-grid operators. Our positioning and navigation capabilities are already being used as well.

NASA, for example, is using our system for urban drone operations at several of its centers. They want to be able to operate in places such as downtown San Francisco or downtown Berlin, where there are many high-rise buildings and GPS signals can be blocked. They need to be able to navigate independently of GPS.

Those are some of our current customers. As awareness of the issue increases, we expect these services to be used by more and more critical-infrastructure companies.

Fascinating. Thank you for the rundown. Where can people find out more if they're interested? Are there articles you've written, a website, or another way to follow your work?

Yeah, absolutely. Our website is a great place to start: www.nextnav.com—N-E-X-T-N-A-V. We also have a substantial social-media presence, where we post relevant articles, reports, and data.

You can also look at material from the European Commission or the US Department of Transportation. Various government agencies have conducted studies on the vulnerabilities of PNT, and information is available there.

The US National Institute of Standards and Technology published a report, I believe in two thousand nineteen, on the overall economic impact of GPS. It's more than one thousand pages, but it is a good read. It shows the magnitude of the issue and the risks we're facing.

Awesome. Thank you very much for your time and for the enlightening information.

Absolutely. Thanks for reaching out, Jonatan. It was great talking with you, and we'll keep moving forward on this.

Thank you very much for your time, Ganesh. Have a good day. Bye.

All right. Thanks, Jonatan.