Inside the race to find GPS alternatives

“Just because of this shorter distance, we will put down signals that will be approximately a hundred times stronger than the GPS signal,” says Tyler Reid, chief technology officer and cofounder of Xona. “That means the reach of jammers will be much smaller against our system, but we will also be able to reach deeper into indoor locations, penetrating through multiple walls.”

A satnav system for the 21st century

The first GPS system went live in 1993. In the decades since, it has become one of the foundational technologies that the world depends on. The precise positioning, navigation, and timing (PNT) signals beamed by its  satellites underpin much more than Google Maps in your phone. They guide drill heads at offshore oil rigs, time-stamp financial transactions, and help sync power grids all over the world.

But despite the system’s indispensable nature, the GPS signal is easily suppressed or disrupted by everything from space weather to 5G cell towers to phone-size jammers worth a few tens of dollars. The problem has been whispered about among experts for years, but it has really come to the fore in the last three years, since Russia invaded Ukraine. The boom in drone warfare that came to characterize that war also triggered a race to develop technology for thwarting drone attacks by jamming the GPS signals they need to navigate—or spoofing the signal, creating convincing but fake positioning data. 

The crucial problem is one of distance: The GPS constellation, which consists of 24 satellites plus a handful of spares, orbits 12,550 miles (20,200 kilometers) above Earth, in a region known as medium Earth orbit. By the time their signals get all the way down to ground-based receivers, they are so faint that they can easily be overridden by jammers.

Other existing Global Navigation Satellite System constellations, such as Europe’s Galileo, Russia’s GLONASS, and China’s Beidou, have similar architectures and experience the same problems.

But when Reid and cofounder Brian Manning founded Xona Space Systems in 2019, they didn’t think about jamming and spoofing. Their goal was to make autonomous driving ready for prime time. 

Dozens of robocars from Uber and Waymo were already cruising American freeways at that time, equipped with expensive suites of sensors like high-resolution cameras and lidar. The engineers figured a more precise satellite navigation system could reduce the need for those sensors, making it possible to create a safe autonomous vehicle affordable enough to go mainstream. One day, cars might even be able to share their positioning data with one another, Reid says. But they knew that GPS was nowhere near accurate enough to keep self-driving cars within the lane lines and away from other objects on the road. That is especially true in densely built-up urban environments that provide many chances for signals to bounce off walls, creating errors.

“GPS has the superpower of being a ubiquitous system that works the same anywhere in the world,” Reid says. “But it’s a system that was designed primarily to support military missions, virtually to enable them to drop five bombs in the same bowl. But this meter-level accuracy is not enough to guide machines where they need to go and share that physical space with humans safely.”