WASHINGTON, July 16 — The Global Positioning System has become so woven into daily life that most people only notice it when it stops working. For the U.S. Space Force, which manages the 31 GPS satellites in medium-Earth orbit, the growing threat of signal jamming has become a pressing national security concern. The signals that guide everything from airplane landings to smartphone maps are remarkably weak.
Government engineers describe the GPS signal reaching Earth as roughly equivalent to a 20-watt light bulb shining from 20,000 kilometers away. That fragility makes the system vulnerable to inexpensive jamming devices that can overwhelm the signal entirely.
A rising tide of interference
The U.S. Government Accountability Office documented a troubling trend in 2021. Since 2015, more than 1,000 reports of GPS interference have been filed in the United States. The Department of Homeland Security has formally identified GPS as a critical infrastructure vulnerability, recognizing that a sustained outage could ripple across transportation, banking, power grids and emergency services.
The Space Force is responding with next-generation satellites. The GPS III and GPS IIIF spacecraft currently under development include improved anti-jamming capabilities.
But these satellites remain in medium-Earth orbit, where the fundamental physics of signal strength cannot be changed.
A different approach from low orbit
Enter Xona Space Systems. The company is building a Positioning, Navigation and Timing (PNT) system called PULSAR that operates from low-Earth orbit, or LEO. The key difference is physical: satellites much closer to Earth can transmit stronger signals that are inherently harder to jam.
Xona’s LEO system represents what engineers call an alternative physical layer. Instead of trying to shield GPS’s weak signal, the company is building a system where the signal itself is more robust.
The U.S. government has also funded development of eLoran, a terrestrial backup system using ground-based radio towers, but LEO PNT is increasingly seen as the more modern solution. What makes PULSAR particularly interesting for users is its design philosophy. The system is built to be interoperable with GPS, meaning receivers could switch between the two networks seamlessly.
For a cargo ship entering a port where jamming has been reported, or a farmer using precision agriculture in a contested area, that redundancy could mean the difference between staying on course and losing position entirely. The technology is still emerging, but the direction is clear.
As jamming incidents continue to rise and the nation’s dependence on precise timing and positioning only grows, the search for backup systems has moved from theoretical to urgent. Xona’s LEO approach offers a glimpse of what a more resilient PNT ecosystem might look like — one where a single point of failure no longer holds the entire system hostage.
