When Russia invaded Ukraine in 2022, GPS jamming quickly emerged as a major problem faced by combatants. Two years later, as jamming technology becomes increasingly sophisticated and widespread, the defense industry is responding with innovations and technology that don’t rely on satellite signals from space.

From camera-based navigation systems that use terrain recognition to artificial intelligence (AI) that fuses data from multiple sensors, new technologies are transforming how military forces navigate in contested environments. The stakes couldn’t be higher: In modern warfare, losing positioning capability means losing the ability to fight effectively.

LEO satellites: a piece of the puzzle

One area that has shown a lot of promise is low-Earth orbit (LEO) satellites. The number of LEO satellites has grown exponentially in recent years, which could provide a big benefit to the sensor-navigation industry. Position, navigation, and timing (PNT) technology that utilizes LEO satellites is in some situations better than GPS, with a more powerful signal and in some cases more accurate.

However, some industry experts have a measured outlook about their role in military navigation.

“LEO satellites continue to be of interest, but they won’t be a silver bullet,” says Dana Goward, president of the Resilient Navigation and Timing Foundation in Alexandria, Virginia, a nonprofit a nonprofit organization that promotes resilient navigation and timing worldwide.

He points out that geopolitical realities may limit their effectiveness. “With Russia, China, and perhaps others having the ability to jam or spoof signals from space, the added resilience from a LEO constellation might not satisfy many,” Goward notes.

But the technology itself shows promise. Frank Armstrong, senior product manager at Kymeta (Redmond, Washington), says that providers of LEO satellite constellations want to be able to provide GPS-like capabilities, either through broadcasting timing signals directly or by enabling ground stations to use the satellites as reference points for position tracking. (Figure 1.)

[Figure 1 | A Falcon 9 rocket carrying 23 Starlink satellites launches from Space Launch Complex 40 (SLC-40) at Cape Canaveral Space Force Station, Florida, March 10, 2024. Starlink satellites are positioned in low-Earth orbit (LEO) U.S. Space Force photo by Joshua Conti.]

But it would be unwise to ignore the limitations of this tech, says Adam Moya, director of business development for aerospace and defense at Benchmark (Tempe, Arizona). “Its major drawback is that it is not a completely independent, noninterference, nonjammable source, which is driving the base need for GPS-denied solutions,” he explains.

This vulnerability to interference, combined with what Goward describes as a growing desire for “sovereign PNT capability” among nations, suggests that LEO satellites will likely be just one piece of a larger navigation puzzle rather than a complete solution.

The role of artificial intelligence

AI and machine learning (ML) could prove to be powerful tools for navigation, particularly in their ability to process and interpret data from multiple sources when GPS signals aren’t available.

“AI’s largest contribution in this front is utilizing sensor fusion and access to alternative signals of opportunity to enhance or replace PNT information in a GPS-denied environment,” Moya says. He notes that researchers are also exploring how AI might “compensate for drift during these outages along with the sensor fusion algorithms.”

This ability to process complex data at the edge of the network is proving valuable for satellite communications companies as well. “AI and machine learning have helped us ... by enabling more complex algorithms at the edge to derive our position from signals of opportunity,” Kymeta’s Armstrong says. “This reduces our reliance on GPS or GNSS [Global Navigation Satellite System] information.”

While the technology shows promise, it’s still maturing.

“We have seen some initiatives to use AI to interpret a variety of sensors, many of which one doesn’t usually think of in terms of navigation and timing, to determine position and aid navigation,” Goward says. “It still seems to be in the early stages, though as we haven’t seem a lot of application. That could change quickly, though.”

A variety of proposed solutions

This is a relatively new technological challenge, so not surprisingly there are a wide range of proposed solutions, each approaching the problem from a different angle – from image-based systems to hybrid satellite terminals and comprehensive engineering services.

Scientific Systems Co. Inc. (SSCI – Woburn, Massachusetts) has developed a camera-based solution called ImageNav, which has received about $45 million in funding and takes a completely different approach to the problem that doesn’t involve using LEO satellites or AI. Instead, the system uses onboard electro-optical (EO) or infrared (IR) digital cameras and fuses the outputs of three different algorithms: stereo terrain correlation, image-based feature matching, and feature-based velocity estimation, says Tom Frost, vice president at the company’s products division.

Kymeta’s Osprey u8 is a GEO [geosynchronous]-LEO terminal that aims to provide multiorbit capability for mission-critical operations while on the move. The system uses a range of receivers and location technology to ensure continuous operation. (Figure 2.)

[Figure 2 | Kymeta’s Osprey u8 hybrid-GEO terminal provides low-profile, vehicle-mounted connectivity for military communications in GPS-denied environments (Image courtesy Kymeta).]

Other new approaches in this area are also emerging. Location-software startup Zephr, for instance, tested a solution in Ukraine that networks ordinary cellphones together to detect and potentially locate GPS jammers, according to a recent Defense One report. The system exploits the various sensors already built into phones – such as automatic gain control, Doppler sensors, and carrier phase measurements – to create what company officials describe as one big, distributed antenna.

The U.K. Royal Navy, meanwhile, is going in an entirely different direction and has delved into quantum technology. Working with U.K. startup Aquark Technologies, the United Kingdom’s naval warfare branch is testing a quantum-positioning system that uses laser-cooled atoms to detect minute changes in motion. Unlike traditional inertial navigation systems that become less precise over time, this quantum approach could potentially maintain accuracy without needing GPS updates, according to a Royal Navy release.

The challenge of power management

Regardless of the nature of the solution, power management in GPS-denied navigation presents varying obstacles. While some solutions require minimal power adjustments, others demand a lot of processing power to maintain effectiveness.

In the satellite communications sector, power consumption isn’t directly tied to antijamming capabilities. “GPS jamming is unrelated to power consumption in the satcom terminal technology space,” Armstrong notes, adding that the company’s Osprey u8 antenna “performs in a GPS- and GNSS-denied environment which has as one of the lowest SWaP [size, weight, and power profiles] in the industry in its class.”

However, alternative navigation solutions often require more substantial power-management considerations. “AltPNT [alternative position, navigation, and timing] solutions such as sensor fusion will require more processing power, which in turn drives a change in power management strategies,” says Benchmark’s Moya. “GPS/GNSS is overall a very-low-power sensor system, but the processing of their input is substantial as in a flight-navigation system.”

Some companies are taking different approaches to the power challenge. SSCI, for example, focuses on optical solutions to reduce power needs.

“We are seeing increased interest in our optical-based ImageNav solution that overcomes electronic jamming in contested environments by using on board cameras,” SSCI’s Frost says. The system “uses inertial navigation system information to match camera imagery, including electro-optical and infrared, against stored georegistered digital terrain elevation data to determine the precise location of a suitable air vehicle or weapon in flight.”

Integrating these new solutions into existing systems presents unique situations. “The challenge will be to adapt the AltPNT solutions to fit into the current systems without significant changes to their certification architecture,” Moya adds.

Open standards and the future

While the Sensor Open Systems Architecture, or SOSA, Technical Standard and open systems approaches have shown promise in many defense applications, their role in GPS-denied navigation solutions remains uncertain – although they undoubtedly will have an impact in the future.

“We are in favor of standardization,” Anderson asserts. “It drives down systems-development costs and allows greater interoperability across multiple networks. With the current pace of change it also enables easier upgrades and more flexible system configurations.” However, he does add that they are “not sure how SOSA and open systems architecture will affect GNSS capabilities.”

The potential impact of open standards may be more apparent at the moment in the commercial sector, a path that then often leads to developments in the defense industry.

“This has more of a play in commercial applications looking for a standardized and certifiable approach to AltPNT,” Moya says. The main problem is that while open standards could help develop common alternative navigation solutions, “this solution can be critical IP [intellectual property] in certain situations,” he says.

Any standardization effort would need to be driven by an industry consortium to resolve this issue, he adds.

SIDEBAR: Uncrewed systems in GPS-denied environments

Navigation in GPS-denied environments poses particular challenges for uncrewed systems, with size constraints often limiting the available solutions.

"It depends on the class of aircraft, but GPS-denied is particularly troublesome for smaller aircraft that do not already have terrestrial navigation systems or the payload capabilities to create an independent AltPNT [any source other than GNSS] system," says Adam Moya, director of business development for aerospace and defense at Benchmark in Tempe, Arizona.

He notes that potential solutions include "a robust, high-integrity data link that could be used to provide external PNT information for the aircraft, and/or AI/ML [artificial intelligence/machine learning] algorithms utilizing visual and IMU [inertial measurement unit] information within the aircraft."

The current conflict in Ukraine highlights these vulnerabilities: "Uncrewed systems of all sizes are being affected by evolving jamming capabilities because many were designed to rely on GPS systems that aren't available in contested environments like Ukraine," says Tom Frost, vice president at the Scientific Systems Company Inc. (SSCI – Woburn, Massachusetts) products division. "The difficulties posed by Russian jamming on the battlefield in Ukraine have forced the designers of uncrewed systems to look for solutions beyond celestial magnetic backup options."

Some solutions are emerging, but many necessarily remain under wraps.

"Unmanned systems are becoming more important, especially in military planning and contingencies,” asserts Dana Goward, president of the Resilient Navigation and Timing Foundation in Alexandria, Virginia. “Yet reliable navigation still appears to be a hurdle. If the military has something, it is likely classified.”

The industry is working on options for uncrewed. Frank Armstrong, senior product manager at Kymeta in Redmond, Washington, notes that the company is "looking at ways to be a provider of some GNSS-type information to these systems from our products but can not elaborate at this time."

SSCI’s Frost says that the company’s ImageNav system is designed for uncrewed aerial system (UAS) manufacturers looking for a low-cost option. (Sidebar Figure 1.)

[Sidebar Figure 1 | Scientific Systems' ImageNav software uses EO/IR cameras and three parallel algorithms to provide GPS-free precision navigation for aircraft operating from 200 feet to 25,000 feet. (Image courtesy Scientific Systems.)]