How GPS jamming works and how to guard against it

Since the conflict in Ukraine, jamming of GNSS signals has become a weapon in its own right within electronic warfare. From consumer-grade jammers to sophisticated systems deployed by state actors, the techniques used take different forms. Countermeasure tools do exist, but their effectiveness remains limited.

On Wednesday, September 24, Margarita Robles, Spain’s Minister of Defense, visited a NATO base in Lithuania where Spanish troops are stationed. According to the news agency Europa Press, her aircraft, an Airbus A330, was targeted by an attempted disruption of its GPS system while flying over the Russian enclave of Kaliningrad.
The flight crew downplayed the incident, explaining that such events are frequent near Kaliningrad. Moreover, the attempt to disable the GPS failed, as the aircraft’s secured system received its signal from a military satellite.

This unfortunate episode came less than three weeks after the alleged jamming of the GPS system of the aircraft transporting Ursula von der Leyen, President of the European Commission, in Bulgaria. The pilot was forced to land manually. In both cases, Russia was singled out.

However, the second GPS jamming attempt remains disputed. On X, the flight-tracking site FlightRadar24 debunked, map in hand, the media version of an hour-long holding pattern for the Falcon 900 carrying Mrs. von der Leyen. It also noted that “the aircraft’s transponder reported good GPS signal quality from takeoff to landing.”
In a video, Pierre-Henri Chuet, pilot and founder of the consulting firm D.Brief, analyzed the events of the flight. Aware of a malfunction in its GPS system, the crew had to switch approach procedures, as they could not rely on radar guidance from the control tower. In this case, Russian interference cannot be proven, and the Falcon may simply have experienced a GPS reception problem, something frequent in this region of Eastern Europe. Bulgaria quickly announced it would not launch an investigation.
“GPS was introduced into civil aviation in the 2000s,” recalls Olivier Dujardin, independent consultant and researcher at the French Center for Intelligence Research (CF2R), “while airplanes have been flying for 120 years. A pilot must be able to read a map and land manually.”

The war in Ukraine has made military jamming widespread

These two widely reported incidents at least served to raise public awareness of GNSS (Global Navigation Satellite System) jamming techniques. The phenomenon is not new in civil aviation. On its website, France’s National Frequency Agency (ANFR) lists confirmed cases of jamming affecting Nantes airport (2017), Lyon-Bron (2018), and Marignane (2019).

In the military sphere, the war in Ukraine has highlighted the widespread use of GNSS jamming. Both belligerents deploy this electronic warfare technique to divert drones or missiles from their intended trajectories.
Such disruptions can spill beyond war zones. In a statement, Lithuanian startup Astrolight cited observations from Latvia’s electronic communications bureau, which claims that Russia disrupts satellite navigation systems from three permanent sites in the Kaliningrad, Leningrad, and Pskov oblasts, creating “widespread risks for civil aviation and critical infrastructure in the Baltic Sea region.”

Maritime transport is also affected. In the Strait of Hormuz, jamming disrupts the GPS of hundreds of ships navigating daily in this strategic zone through which roughly 20% of the world’s oil transits. Frequent positioning errors complicate navigation and make it uncertain. In June, two tankers collided, Courrier International reports.

Buying a jammer on e-commerce sites

Jamming, whose coverage can extend from a few meters to several dozen kilometers, is not reserved for state actors. Anyone can buy a jammer the size of a USB stick from mainstream e-commerce sites. Plugged into a car cigarette lighter, it can disable not only the vehicle’s GPS but also that of nearby vehicles.

Truck drivers, delivery workers, or sales representatives use such gadgets to prevent their employer’s “tracking device” from geolocating them. Car thieves can also use a jammer to disable GPS tracking. Of course, their possession and use are strictly prohibited. Under Article L. 39-1 of the French Postal and Electronic Communications Code, offenders face up to six months in prison and a €30,000 fine.

Jamming can also occur unintentionally. A faulty telecommunications device, such as a Wi-Fi router or a relay antenna, may emit outside its operating frequency and interfere with the GNSS band. An elderly woman’s internet box once jammed a neighboring industrial site’s equipment, the ANFR reports.

Denial of service, spoofing, and meaconing

Jamming techniques affect all geolocation systems, whether American (GPS), European (Galileo), Russian (Glonass), or Chinese (Beidou). “The simplest method is to emit ‘noise’ in the frequency band used by GNSS,” explains Alexandre Vervisch-Picois, research director at Télécom SudParis. “The radio signal overlays the geolocation system’s signal and disrupts its functioning.”

This jamming technique results in a denial of service: the receiver can no longer calculate the user’s position. According to an article published by The Conversation, it is possible because satellite signals are transmitted at very low power. “A jammer located several kilometers away and emitting just a few milliwatts—about the same as a Wi-Fi transmitter—can suffice,” adds Vervisch-Picois. “It’s the best simplicity-to-efficiency ratio.”

Another common technique is spoofing. This is not strictly speaking jamming, since it involves generating fake GNSS signals with the same technical characteristics as genuine ones. Amplified, they overpower authentic signals. Deceived, the receiver displays an incorrect position, sometimes dozens of kilometers from reality.
“All GNSS signals are vulnerable to spoofing except the encrypted signal reserved for NATO forces, which requires a decryption key,” notes Olivier Dujardin. A variant, meaconing, involves capturing and retransmitting authentic GPS signals with a time delay, creating positioning errors.

Expensive countermeasure tools

The main defense against such interference relies on Controlled Radiation Pattern Antennas (CRPA). Developed by companies such as Thales, these systems are deployed on military aircraft, helicopters, drones, ships, and certain sensitive civilian equipment. They use advanced spatial signal processing techniques to maintain satellite reception in hostile environments.

In principle, the different antennas of a CRPA network receive legitimate GNSS signals. Electronic processing combines these signals from satellites to strengthen them while weakening interfering signals from other directions. However, by faithfully replicating GNSS signals, sophisticated spoofing attacks make it more difficult to distinguish between authentic and malicious signals.

“Other techniques combine optical navigation and GSM networks to re-localize and avoid being completely lost,” adds Olivier Dujardin. “They provide a degraded service with reduced accuracy.” A multi-receiver navigation system can, for example, cross-check GPS data with inertial navigation system (INS) data, based on an aircraft’s acceleration and rotation sensors.

“Whatever countermeasure is implemented, the jammer always ends up winning—even though military signals hold up better,” concludes Vervisch-Picois. Moreover, these countermeasure devices face constraints in size, weight, and bulk, which limit their integration into some equipment.
Not to mention their cost. “The higher the sophistication of the threat, the greater the expense,” observes Vervisch-Picois. “It’s a technical and economic equation to weigh depending on the criticality of the use. A civil engineering surveyor, for instance, does not need an anti-jamming device.”

This cost partly explains why commercial smartphones are not equipped with anti-interference systems. “It would multiply the cost of a basic GPS chip—which is about one dollar—by a factor of 10 to 100,” continues the expert. On top of that comes the space taken up by the device and its computing resource consumption, which would further reduce a phone’s battery life.