PNT is an integral part of future Satellite Services

By Adam Price, VP of PNT Simulation at Spirent Communications

The promise of cellular-to-satellite connectivity & the proliferation of new satellite navigation systems makes PNT technologies even more critical in the future  

Positioning, navigation and timing (PNT) technologies are not only essential to existing satellite services, but are a key element in the growing number of low-Earth orbit (LEO) satellite constellations being devised to deliver cellular-to-satellite connectivity. In addition, constellations being designed to facilitate lunar navigation are extending the requirements and capabilities of PNT technology.

At the most basic level, PNT technology refers to the determination of precise location (positioning), the ability to keep accurate time from coordinated universal time (timing) and the capacity to determine attitude and motion (navigation). PNT systems, which include Global Navigation Satellite Systems (GNSS) such as Global Positioning System (GPS), enable all types of use cases in aviation, transportation, logistics and more. Plus, GNSS such as GPS are key elements in cellular networks and smartphone applications that are used by millions of consumers every day.

According to BIS Research, the global PNT technology market was valued at $961.7 million in 2020 and is estimated to reach $8.3 billion by 2031, growing at a compound annual growth rate (CAGR) of 22.45%.

But PNT technologies do have some challenges. For example, GNSS signals are vulnerable to malicious attacks in the form of jamming and spoofing.  And while modern GNSS signals deliver a high level of accuracy, that accuracy degrades depending upon factors such as atmospheric conditions, receiver design, and signal obscuration.

Fortunately, the industry is working to mitigate any security vulnerabilities through technologies such as Galileo’s Open Service Navigation Message Authentication (OSNMA) and the GPS Chips-Message Robust Authentication (CHIMERA). In addition, new simulation technologies are making GNSS lab testing more useful and making it possible to simulate GNSS signal environments more realistically, enabling greater robustness. 

Satellite-to-cellular connectivity

Recently there’s been a lot of buzz about the cellular-to-satellite connectivity opportunity. Apple, for instance, launched its “Emergency SOS via Satellite” service in November 2021. The service uses Globalstar’s low-Earth orbit (LEO) satellite constellation and provides text messaging capability in areas without cellular coverage. The service is available to iPhone 14 users.

But Apple isn’t alone. Android smartphones will also have satellite-to-cellular capability thanks to Qualcomm’s new partnership with Iridium that was announced earlier this year. In addition, British manufacturer Bullitt Group also said it is launching a new smartphone with satellite messaging that connects to Skylo, a connectivity company that says it is working with established satellite operators to deliver connectivity.

And there’s more. coverage-Mobile has formed a technical partnership with SpaceX that will use the Starlink LEO constellation to deliver connectivity outside cellular coverage. And AT&T has hinted that it is working with AST SpaceMobile to develop some type of consumer application that will use satellite connectivity.

While Apple’s satellite-to-cellular service is already available today, the others are expected to follow in the very near future. Qualcomm and Iridium said their service, called Snapdragon Satellite, will be available by the second half of 2023.

Research firm Northern Sky Research, which specializes in the satellite communications market, is bullish on satellite-to-cellular connectivity and believes it could be a big opportunity for satellite companies to reach billions of new customers. NSR estimates that the service will deliver as much as $66.8 billion in 10-year cumulative revenues for the satellite industry.

This technological development, and other services delivered from LEO, are all underpinned by precision PNT being delivered to (and, in some cases, from) the constellations. All of this means the downstream value of PNT technology continues to grow exponentially. It would have been hard for the USAF to know, when designing the GPS constellation, just how far-reaching the benefits of making PNT ubiquitous would be!

New navigation systems

Beyond satellite-to-cellular connectivity, there are also a number of active initiatives aimed at expanding the space service volume beyond what exists today to include in-orbit and lunar applications. 

The European Space Agency (ESA), for example, is developing a new satellite navigation constellation that will supplement Europe’s Galileo satellite system. These satellites, which are called LEO-PNT satellites, will orbit just a few hundred kilometers in space and are expected to deliver PNT data that is more accurate than what exists today and is available everywhere.

The project is studying whether these orbits and signals will be able to offer better signal strength, more reliable indoor coverage and be more resistant to jamming. In addition, because they are closer to Earth, the ESA estimates that these LEO-PNT satellites will be less expensive to build and launch.

ESA told the Ministerial Council late last year that the goal of the LEO-PNT initiative is to build and fly six to 12 satellites and test their capabilities. This demonstration is expected to happen in 2026.

In addition, ESA is also working with NASA to establish a satellite navigation system around the moon. The reasons for this type of navigation system could be many – PNT on the surface of the Moon, space-based testing of PNT-enabled equipment, and to extend the range of navigation technologies deeper into space for further exploration, to name a few.

The easiest method for providing navigation in space is by using satellites that are currently rotating around the Earth. However, because existing GNSS satellites are low-powered and directed towards the Earth, the available received power levels are very low. But ESA and NASA are working to find ways to harness the signals from the Earth’s satellites and use them to navigate future moon missions.

One possible solution is a receiver developed by SpacePNT for ESA, called NaviMoon, that is expected to launch on the Lunar Pathfinder mission in 2025 or 2026. ESA believes NaviMoon will be able to determine position to within 200 feet as far away as the Moon. 

While LEO constellations offer great possibilities for PNT technologies in the near-term, lunar and in-orbit applications present even greater promise for PNT in the more distant future.

In any case, PNT technologies continue to hold great value because they provide the necessary data to ensure that these initiatives are operating effectively today as well as provide great opportunity for the next stage in space communications.