In 2021, a team led by Zak Kassas, director of the Autonomous Systems Perception, Intelligence, and Navigation (ASPIN) Laboratory at The Ohio State University, showed how electronically eavesdropping on signals from six Starlink satellites could pinpoint locations on Earth to within 8 meters of accuracy—although that required 13 minutes of tracking rather than delivering instantaneous results.

Such opportunistic eavesdropping is challenging, because Starlink is consistently optimizing for its primary satellite Internet service by turning beams on and off, or sometimes switching beams as the fast-moving satellites talk to many different users, Kassas explained. That creates unpredictable jumps in the signal timing estimates that the researchers rely upon to calculate positioning data.

To tackle those challenges, Kassas and his colleagues use Doppler measurements of signal frequency changes that reflect satellite motions relative to the receiver, along with software algorithms to correct for timing errors. They have also deployed phased-array antennas—capable of communicating with just one or two satellites at a time—in combination with low-gain, omnidirectional antennas that can capture signals from nearly 10 satellites at a time. By 2025, the researchers had shown how to harness signals from an average of three Starlink satellites to deliver positioning results to within 2 meters of accuracy in just 20 seconds.

But this general eavesdropping strategy is not just limited to Starlink’s thousands of satellites—they have also exploited satellite signals from Orbcomm, Iridium, Starlink, OneWeb, NOAA, and the dedicated PNT constellation, Xona. “I’m not really married to Starlink—I love them all,” Kassas said.

The team has demonstrated this alternative navigation solution with ground vehicles, a high-altitude balloon, and a drone. One of the latest experiments showed how exploiting signals from both Starlink and OneWeb satellites could improve ship navigation accuracy off the west coast of Greenland in the Arctic, meaning that the technique could probably work nearly anywhere on Earth.

All this suggests that people may not have to wait much longer for new GPS alternatives, whether they come directly from Starlink or third parties. Kassas and his team have already licensed their technology to some organizations. “I think people are hungry and hurting in the absence of GPS or GNSS, and they want these solutions,” Kassas told Ars.