In March 2024, a plane carrying the UK defense minister had its GPS signal jammed as it travelled close to the Russian exclave of Kaliningrad on a journey between the UK and Poland. The UK government later said the plane was never in danger but that jamming incidents were not unusual in the region. Indeed, various groups have noted that GPS jamming has become common since the start of the Russian-Ukraine war.
For decades, the standard backup for this kind of navigational failure has been inertial navigation, a method for tracking motion using accelerometers and gyroscopes. But these systems have an inherent weakness: tiny errors add up over time, causing position estimates to drift, potentially by many kilometers over long journeys. That makes them unacceptable in many critical applications.
What navigators desperately need is a new way to work out where they are that does not rely on satellite signals that can be jammed. Ideally, this system should be entirely passive so that it does not reveal its own location, unlike radar, for example.
