Scientists develop GPS alternatives as satellite jamming threat grows

Growing concerns over GPS jamming are driving researchers to develop alternative navigation systems that could keep aircraft, ships and other vehicles moving when satellite signals are disrupted.

A study led by Todd Humphreys of the University of Texas at Austin has linked dozens of widespread GPS disruptions recorded across Europe and elsewhere since 2019 to a constellation of Russian satellites. The research suggests that jamming or accidental interference from space could potentially affect navigation across an entire continent, The Economist writes. 

One alternative is magnetic navigation (MagNav), which uses variations in Earth’s magnetic field to determine position. The planet’s crust contains magnetic irregularities that create a distinctive map of anomalies across land and sea. Aircraft equipped with magnetometers can detect these variations and match them with existing maps to establish their location.

Australian company Q-CTRL demonstrated a MagNav system last year that used an optically pumped magnetometer to measure local magnetic fields. The system reportedly outperformed a leading GPS alternative during a test flight over New South Wales.

Another approach uses diamond-based sensors. Canadian company SBQuantum is developing an NV-diamond magnetometer capable of measuring both the strength and direction of magnetic fields. Its developers believe this could eventually allow more precise navigation using three-dimensional magnetic maps.

The main challenge for magnetic navigation is the lack of comprehensive and sufficiently accurate maps of Earth’s crustal magnetic field. Companies are therefore conducting their own surveys or seeking to combine existing datasets.

Researchers are also exploring “signals of opportunity” — radio transmissions that were not originally designed for navigation but can be used to determine position.

One method measures the Doppler shift of satellite signals. As a satellite approaches and moves away, the frequency of its transmission changes, allowing a receiver to estimate its position using information about the satellite’s orbit.

ASPIN Lab at Ohio State University demonstrated its Matrix system in August 2024 aboard a cruise ship off western Greenland. Using signals from 21 Starlink and OneWeb satellites, the system placed the vessel within 27 metres of its actual position, given a known starting position and speed.

Researchers are working to improve that accuracy. Virginia Tech’s Mark Psiaki is developing a system using a fixed reference receiver to provide corrections to other receivers. He estimates the approach could eventually achieve positioning accuracy of around 10 metres.

Psiaki also proposes combining distance measurements from Starlink satellites with Doppler data, potentially bringing positioning accuracy to about two metres.

Researchers have even tested the use of signals from mobile-phone towers for navigation. ASPIN Lab has used tiny changes in cellular signals to navigate an aircraft during tests with the US Air Force.

As GPS becomes increasingly vulnerable to disruption, these emerging technologies could provide alternative sources of positioning based on Earth’s magnetic field and the growing network of radio signals already surrounding the planet.

By Sabina Mammadli