Report 025 · Defense Tech
The coverage tells you your GPS is under attack. It rarely tells you the harder part: who is doing it, and from where. Finding a hidden transmitter is its own discipline, and in 2025 a research team used it to trace the Baltic's jamming and spoofing to specific sites near Kaliningrad. From someone who hunted emitters for a living, how you find a jammer, and why every transmitter gives itself away the moment it keys up.
In a companion report I pulled apart the two attacks the news folds into one phrase: jamming, which denies your position and lets you know, and spoofing, which hands you a confident false one and doesn't. That piece was about what is being done to your receiver. This one is about the question that comes next and that most coverage skips entirely. If a region's GPS is being jammed and spoofed almost daily, who is doing it, and can you actually point at where they are?
The answer is yes, and the method is old. I spent my career as a Counter-IED and electronic-warfare officer, and a large part of that job is the reverse of hiding: finding the other side's transmitters. It has a plain name, emitter geolocation, and it rests on a fact that is inconvenient for anyone operating a jammer. To transmit is to be found.
In 2025 an international team led by Jarosław Cydejko of Gdynia Maritime University, working with Dennis Akos at the University of Colorado, set up a network of monitoring stations around the Gulf of Gdańsk on the Polish Baltic coast. They were not just recording that interference was happening. They were listening for the interference at several stations at once, so they could work backward to its source. The peer-reviewed writeup appeared in the journal GPS Solutions in 2026 under a title that names the technique outright: emitter detection and localization in real time using a time-difference-of-arrival system.
The results, reported as the work came out, were specific. The team traced the interference to two coastal sites inside the Russian enclave of Kaliningrad, to within about one kilometer. The primary source was the area of the Okunevo antenna complex, a site that hosts Russian electronic-warfare units and, in earlier satellite imagery, a truck-mounted Murmansk-BN array with 32-meter antennas. A separate jamming event traced to the harbor town of Baltiysk. Both jamming and spoofing were coming from named places you could put a finger on, not from some diffuse fog over the sea.
The trick behind that one-kilometer fix is simpler than it sounds. A radio signal travels at the speed of light, roughly thirty centimeters every nanosecond. Set up several receivers at surveyed locations, and a signal from a single transmitter will arrive at each of them at a very slightly different instant, because each receiver sits a slightly different distance away. Those tiny differences in arrival time are the whole game.
Measure the difference in arrival time between one pair of receivers and you have not pinned the source, but you have narrowed it: the transmitter has to lie along a curve where that particular time difference holds. Add a second pair and you get a second curve. Add a third and the curves cross. Where they intersect is your emitter. The one hard requirement is that the receivers share an extremely precise common clock, so a nanosecond measured at one station means the same nanosecond at another. The irony is that the cleanest source of that shared time is GPS itself, the very system under attack.
None of this is exotic. It is the same principle that lets a phone network place a handset, that lets astronomers locate a burst of radio noise, and that lets an electronic-warfare unit find the radar or the jammer it is hunting. What changed in the Baltic case is not the physics but the will to point the equipment at a specific act of interference and publish where it came from.
Here is the part that folds neatly back into the jamming-versus-spoofing distinction. A jammer is a brute. Its entire method is to be as loud as possible across the GPS band, drowning the faint satellite signal in noise. That is exactly what makes it easy to geolocate. It is a floodlight in a dark field, screaming its own position to anything listening on the right frequency. The property that makes a jammer effective, raw power, is the property that gives it away.
A spoofer is the subtler target, because its whole art is to look like a real satellite rather than to shout. But it still has to transmit, and anything that transmits can, in principle, be triangulated. That the Baltic team pinned both a jammer and a spoofer is the point worth holding onto: deception buys the attacker confusion at your receiver, but it does not buy invisibility at the antenna. The signal that fools your navigation still has to leave a real transmitter at a real place, and that place obeys the same geometry as everything else.
It is fair to ask what a one-kilometer fix actually buys you, since knowing where a jammer sits does not switch it off. Two things. The first is attribution. There is a large difference between "the Baltic has mysterious GPS problems" and "the interference resolves to a known electronic-warfare site in Kaliningrad." The first is weather. The second is evidence, the kind that supports a diplomatic protest, a legal complaint, or a military decision. Deniability evaporates when the source has coordinates.
The second is that geolocation is the front half of every real countermeasure. You cannot avoid, shield against, or if it ever came to it, physically address a source you cannot place. In the field the sequence is always the same: detect that something is transmitting, characterize what it is, locate where it lives, then decide what to do. The Baltic work is a civilian, published version of that first three-step chain, run on a real adversary's real emitters.
The lesson an electronic-warfare officer internalizes early is that emission is exposure. Every transmitter is also a beacon announcing itself. It is why radio discipline and emission control are drilled so hard, why a unit that has to stay hidden stays quiet, and why the drone that phones home, the radar that sweeps, and the jammer that screams can all, given a few synchronized listeners, be drawn on a map. The Baltic result is worth remembering the next time interference is described as coming from "somewhere over the sea." With the right receivers and a shared clock, somewhere becomes a set of coordinates. The attacker who denies your navigation is, at that same moment, quietly surrendering his own.
U.S. Army combat veteran (Counter-IED / Electronic Warfare), peer-reviewed researcher in microwave spectroscopy, and founder & CEO of Shroombiosis. Consults on laboratory operations, AI, and supplement formulation.