Jamming: Polish researchers suspect GPS jammers on ships in the Baltic Sea

Ships sailing in the eastern Baltic Sea are at least partly responsible for the massive disruptions to satellite navigation systems such as GPS in the region that have been complained about since the end of 2023 at the latest. This is the result of a new study by Polish researchers. The scientists observed GPS interruptions at ground level between June and December 2024 using a sensor they had installed at the Gdynia University of the Sea in northern Poland. The university is located around 35 kilometers from Gdansk and 120 kilometers from the Russian Kaliningrad Oblast (Königsberg). In total, they detected disruptions to global navigation satellite systems (GNSS) over a period of 84 hours. These had caused persistent problems in the area for ships to stay on course.

In the analysis, which was limited to the Bay of Gdansk, the experts identified jamming, in which the radio signal from the satellites is disrupted, as the main cause. Spoofing did not play a major role. This involves a third party transmitting previously recorded real or false satellite signals. In October, the researchers recorded the highest jamming activity with six major jamming incidents with a total duration of 29 hours. They identified two primary types of interference: from June to September, the team mainly encountered so-called multi-constellation jamming, which affects several GNSS systems. From October onwards, they identified multidimensional interference for the first time, indicating changed jamming tactics and possibly more sophisticated techniques.

Special monitoring network required

The scientists also recorded long-lasting interference events of more than seven hours, which, according to them, "significantly affected GNSS-dependent maritime navigation, port operations and infrastructure reliability". They observed a significant deterioration in positioning accuracy, with errors increasing from nominally 3 to 5 to over 35 meters, posing safety and operational risks. According to the study, however, there is no correlation between terrestrial GNSS interference and influences on the Automatic Dependent Surveillance – Broadcast (ADS-B) air traffic control system. This reinforces the limitations resulting from the exclusive use of airborne surveillance systems around threats to ground-based infrastructure.

The team also speaks of "clear indications of mobile maritime sources of interference" in international waters. These showed movement patterns "consistent with ships in the Baltic Sea". This is consistent with reports of relevant special equipment found on ships in the Russian shadow fleet, such as the Eagle S. The tanker is suspected of having severed the Estlink2 submarine cable between Finland and Estonia in December. The authors therefore see an urgent need for a special GNSS interference monitoring network along the Baltic Sea coast. Such a network could provide localized real-time data to accurately assess threats, detect sources of interference and improve infrastructure resilience. According to other findings, a jamming facility known as the "Baltic Jammer" is located in Kaliningrad, which is primarily focused on air traffic.

(vbr)