Who cares about the Baltic Jammer? (39c3)

Reports of GNSS interference in the Baltic Sea have become almost routine — airplanes losing GPS, ships drifting off course, and timing systems failing. But what happens when a group of engineers decides to build a navigation system that simply *doesn’t care* about the jammer? Since 2017, we’ve been developing **R-Mode**, a terrestrial navigation system that uses existing radio beacons and maritime infrastructure to provide independent positioning — no satellites needed. In this talk, we’ll share our journey from an obscure research project that “nobody needs” to a system now seen as crucial for resilience and sovereignty. Expect technical insights, field stories from ships in the Baltic, and reflections on what it means when a civilian backup system suddenly attracts military interest. Since 2017, our team at DLR and partners across Europe have been working on an alternative to satellite navigation: **R-Mode**, a backup system based on terrestrial transmitters. Our main testbed spans the Baltic Sea — a region now infamous for GNSS jamming and spoofing. We’ll start by showing what GNSS interference actually means in practice: aircraft losing navigation data, ships switching to manual control, and entire regions facing timing outages — such as the recent disruption of telecommunications in Gdańsk during Easter 2025. Then we’ll take you behind the scenes of building R-Mode: designing signals that can coexist with legacy systems, installing transmitters along the coast, and testing shipborne receivers in rough conditions. We’ll share personal moments — like the first time we received a stable position fix in the middle of the Baltic. Finally, we’ll talk about perception and politics: how a “research curiosity” became a critical infrastructure project, why ESA now wants to build a *satellite* backup (with the same vulnerabilities), and how it feels when your civilian open-source navigation system suddenly becomes strategically relevant. Licensed to the public under http://creativecommons.org/licenses/by/4.0 about this event: https://events.ccc.de/congress/2025/hub/event/detail/who-cares-about-the-baltic-jammer-terrestrial-navigation-in-the-baltic-sea-region