The Bornholmslinjen ferries that cross the Baltic Sea often do so without GPS guidance. Many ships are experiencing jamming or spoofing incidents, so crews increasingly have to rely on more traditional tools such as radar, compass, and charts. On several occasions, the Danish Defence Intelligence Service (FE) has assessed that it is highly probable that Russia is behind the targeted disruptions in the Baltic Sea region.
Jamming causes vessels to lose connection to GPS satellites and thus their position data, whereas spoofing is more complex. Spoofing tricks the GPS receiver into thinking it is in a completely different location because it receives a false signal mimicking the satellites. A ship in the Baltic Sea can suddenly get indications that it is in the middle of Poland.
GPS is the most widely used and accurate navigation system in the world, but the satellite signals are weak and therefore vulnerable. This makes GPS an obvious target in conflict zones like Ukraine and the Middle East, where spoofing and jamming are often used to disrupt enemy drone and missile guidance.
"By and large, spoofing and jamming are just disruptive, but in military contexts, it risks thwarting your entire mission if you need to hit a specific target," says Søren Reime Larsen, postdoc at DTU Space with special expertise in GPS signals.
That's why there is a strong international focus on developing alternative technologies that can act as a backup to GPS. One of them is MagNav—magnetic navigation.
