Inside Jammertest 2025: What Europe's Largest GNSS Stress Test Reveals About Resilient Positioning

At nearly 70 degrees North and 300 km inside the Arctic Circle, the small village of Bleik on Norway’s Andøya island seems an unlikely place for cutting-edge technology warfare. But for one week each September, this remote fishing community transforms into ground zero for the world’s most realistic GNSS interference testing. Jammertest 2025 brought together 360 participants from 120 organizations across 20+ countries—and the findings carry urgent implications for anyone relying on satellite positioning and timing.

This isn’t theoretical research. The test scenarios replicated exactly what’s happening right now across the Baltic, Eastern Europe, and the Mediterranean. And the results reveal both sobering vulnerabilities and promising paths forward.

Why Jammertest Matters Now More Than Ever

The Geopolitical Reality

GNSS interference has evolved from an edge-case concern to a daily operational reality. Commercial aircraft routinely encounter GPS jamming and spoofing across:

Baltic Sea region: Persistent interference affecting civilian aviation and maritime operations
Eastern Europe: Systematic GNSS denial zones affecting cross-border transportation
Mediterranean: Documented spoofing incidents affecting cruise ships and commercial vessels
Middle East: High-intensity electronic warfare impacting civilian infrastructure

The European Space Agency puts it bluntly: “Interference is the consequence of the success of satellite navigation.” The more we depend on GNSS, the more attractive a target it becomes.

GPS interference map showing jamming activity across Europe, with red and yellow hexagons indicating areas of reported navigation accuracy issues

The Economic Stakes

Independent studies estimate GNSS outage costs at up to €1 billion per day for major European economies. This isn’t hyperbole—timing synchronization alone underpins:

Financial markets: Trade timestamps and high-frequency trading
Power grids: Phase synchronization across interconnected networks
Telecommunications: 5G networks and timing-critical backhaul
Transportation: Air traffic control, railway signaling, maritime navigation

When your timing is off by three minutes (as happened to one receiver during Jammertest spoofing tests), the cascading effects can be catastrophic.

The Test Environment: Where Mountains Meet the Sea

Aerial view of Jammertest 2025 test site at Bleik, Andøya, Norway showing the dramatic Arctic landscape

Jammertest’s location isn’t accidental. The geography creates a natural laboratory:

Eastern mountains act as barriers containing interference signals
Western coastline opens toward the Norwegian Sea for maritime testing
Sparse population minimizes civilian impact
Arctic latitude provides unique multipath and ionospheric conditions

The 2025 event ran September 11-19, with testing active from 08:00 to 22:00 daily across multiple zones: Grunnvatnet, surrounding roads, Andenes Airport (September 18), and offshore areas near Bleiksøya (September 16-18).

Seven Norwegian government agencies partnered to host: the Public Roads Administration, Communications Authority, Defense Research Establishment, Metrology Service, Space Agency, Mapping Authority, and Avinor (civil aviation).

GNSS antennas and receivers deployed during field testing at Jammertest

Attack Methodologies: How GNSS Gets Broken

Jammertest 2025 featured approximately 100 interference scenarios—significantly more complex than previous years. Understanding these attack vectors is essential for building resilient systems.

Jamming: Denial Through Noise

Jamming overwhelms receivers with interference, blocking legitimate signals. The test program included:

Continuous-Wave (CW) Jamming

Fixed-frequency interference at 47 dBm (~50 watts)
Targeted individual bands: L1, L2, L5, E6
Swept from approximately 1150 MHz to 1620 MHz

Chirp Jamming

Rapidly sweeping frequency interference
More effective against adaptive receivers
Tests receiver agility and filtering capabilities

Selective Multi-Band Jamming

Sequential high-power campaigns across frequency ranges
Simulates targeted denial of specific constellations
Forces receivers to adapt with remaining signals

Handheld Jammer Scenarios

Low-power, close-proximity interference
Simulates common commercial jamming devices
Tests near-field receiver resilience

Spoofing: Deception Through Fake Signals

Spoofing broadcasts false GNSS signals to mislead receivers. Jammertest tested both major variants:

Coherent Spoofing

Aligns with genuine satellite signals
Gradually takes over receiver tracking loops
Much harder to detect—appears as signal continuation
Tested with both real and synthetic ephemeris data

Incoherent Spoofing

Doesn’t align with genuine signals
Creates obvious discontinuities
Easier to detect but still dangerous if detection is weak

Mobile Spoofing

False trajectories during driving tests
Simulated incorrect vehicle positions
Tested receiver response to gradually shifting positions

Time Spoofing

Manipulated GNSS time signals
Forced sudden clock jumps (minutes to years)
Critical for timing-dependent infrastructure

Meaconing: Replay Attacks

Meaconing captures, delays, and rebroadcasts authentic signals. This creates legitimate-looking but misleading positioning data—particularly dangerous because the signals themselves are genuine.

Receiver Performance: Who Held the Line?

Multiple manufacturers tested their equipment under identical conditions. The results reveal significant performance disparities.

Septentrio: AIM+ and OSNMA Validation

Septentrio’s receivers with AIM+ (Advanced Interference Mitigation) technology demonstrated:

Under Chirp Jamming:

Detected and mitigated interference
Maintained centimeter-level accuracy
Competitor receivers showed errors from several meters to >10 meters

Graph comparing GNSS receiver performance under jamming conditions, showing Septentrio maintaining accuracy while competitors show significant errors

During Circular Spoofing Tests:

Successfully rejected false positioning signals
Raised spoofing flags to alert operators
Competitors either accepted spoofed data or provided no warning

Graph showing spoofing detection performance with Septentrio rejecting false signals while competitors follow spoofed trajectory

Time Spoofing Scenario:

Maintained accurate timing throughout
Competitor receiver displayed time three minutes in the past

Graph comparing timing receiver performance during spoofing attack, showing Septentrio maintaining accurate time while competitor shows 3-minute offset

OSNMA (Open Service Navigation Message Authentication) Validation:

Successfully authenticated Galileo signals
Flagged spoofing attempts in real-time
Demonstrated end-to-end cryptographic protection

u-blox: Integrity Over Continuity

The u-blox ZED-X20P followed a specific design philosophy: protect integrity even at the cost of continuity.

Under Coherent Position Spoofing (GPS-only and Galileo-only):

Detected spoofing attacks
Entered a no-fix state to preserve integrity
Competing receivers followed spoofed trajectories and reported false positions

The key insight: when facing high-fidelity spoofing that closely mimics real signals, entering no-fix is the correct response. Reporting a deceptive location is worse than reporting no location.

SBG Systems: Anti-Jam Antenna Evaluation

SBG Systems conducted extensive testing of passive and CRPA (Controlled Reception Pattern Antenna) systems:

Test Activities:

Field driving tests near and within jammed zones
Mobile spoofing evaluations with adjusted configurations
High-latitude gyrocompassing trials

Key Outcomes:

Collected terabytes of data for post-event analysis
Validated INS (Inertial Navigation System) coasting during GNSS denial
Demonstrated tight-coupling benefits under interference

Their flight control solution for unmanned aircraft was tested against:

Partial GNSS disruptions
Full signal denial
Sophisticated spoofing attempts
Multi-scenario jamming

The results validated their guidance, navigation, and control solution under conditions now observed in real-world conflict zones.

Defense Technologies: What Actually Works

Jammertest 2025 validated several approaches to GNSS resilience.

Multi-Frequency Reception

When specific bands face interference, receivers leveraging multiple frequencies can maintain positioning:

L1/E1: Primary civilian band (~1575.42 MHz)
L2: Legacy GPS (~1227.60 MHz)
L5/E5: Modernized signal (~1176.45 MHz)
E6: Galileo High Accuracy Service (~1278.75 MHz)

Receivers using all available frequencies showed substantially better resilience than single-band units.

Galileo OSNMA

The Open Service Navigation Message Authentication proved its value:

Cryptographic verification of navigation data
Detection of spoofed Galileo signals
End-to-end authentication from satellite to receiver

OSNMA doesn’t prevent jamming, but it definitively identifies whether received signals are authentic—critical for spoofing defense.

AIM+ and Similar Anti-Jam Technology

Advanced interference mitigation combines:

Pulse blanking: Removing impulsive interference
Notch filtering: Excising narrowband jammers
Adaptive algorithms: Real-time response to changing interference

Septentrio’s AIM+ maintained centimeter accuracy under conditions that pushed competitors to meter-level errors.

CRPA (Controlled Reception Pattern Antenna)

Null-steering antenna arrays can:

Identify jammer direction
Create antenna pattern nulls toward interference sources
Maintain reception from legitimate satellites

SBG Systems’ CRPA testing demonstrated this approach’s value under real-world conditions.

INS Integration (Sensor Fusion)

When GNSS fails, inertial navigation systems provide bridging:

Gyroscopes and accelerometers track motion without external signals
Tight coupling with GNSS improves overall solution quality
INS coasting buys time during GNSS denial

The key is tight integration—loose coupling isn’t enough under extended denial.

Conservative Detection Philosophy

Perhaps the most important finding: integrity must trump continuity.

When facing sophisticated spoofing:

Detect the anomaly
Flag the warning
Enter no-fix state if necessary
Never report false positions as valid

Receivers that accepted spoofed trajectories without warning represent a greater risk than those that entered protective no-fix states.

ESA’s Perspective: 100 TB of Reality

The European Space Agency participated for the third consecutive year, with specific objectives:

Testing Activities:

Evaluated EGNOS and Galileo signal robustness
Assessed antenna performance (consumer-grade to military-specification)
Tested novel receiver technologies from ESA programs
Monitored next-generation EGNOS ground receivers

Data Collection: Over 100 TB of data were recorded and are now available for replay at the ESA Navigation Laboratory. This enables:

Post-event analysis by industry partners
Validation of new equipment against real interference
Development of improved mitigation algorithms

Rafael Lucas of ESA emphasized that costs of GNSS outages “could reach billions of euros daily for Europe.” This isn’t about protecting gadgets—it’s about protecting critical infrastructure.

Key Technical Takeaways

For Receiver Designers

Multi-layer detection is mandatory—no single technique catches all attacks
Integrity beats continuity when facing sophisticated spoofing
OSNMA adoption should accelerate—it works in the real world
AIM+ class technology delivers—the performance gap is quantifiable
Test in realistic conditions—laboratory testing isn’t enough

For System Integrators

Budget for multi-frequency, authenticated receivers—the premium is justified
Integrate INS tightly—loose coupling won’t survive extended denial
Consider CRPA for high-value applications—the physics work
Plan for graceful degradation—what happens when GNSS fails?
Implement integrity monitoring—don’t just use position data blindly

For Infrastructure Operators

Timing is the soft spot—three-minute time spoofing is catastrophic for finance/telecom
Redundancy is non-negotiable—single-source PNT is single-source failure
Consider eLORAN and other backups—diverse signal sources matter
Monitor for interference continuously—detection enables response

The Bigger Picture: Resilience as the New Standard

Participants gathered at Jammertest 2025, showing the scale of international collaboration

Jammertest’s head captured the event’s philosophy: “The goal is that every receiver is knocked out at some point during the campaign.” This isn’t about finding perfect equipment—it’s about understanding failure modes and building appropriate responses.

The 2025 event demonstrated that resilient GNSS isn’t built in the lab—it’s proven in the field. The scenarios tested weren’t hypothetical; they’re happening daily across conflict zones and, increasingly, in civilian airspace.

The industry response is encouraging:

OSNMA is ready and validated
AIM+ class technology delivers measurable performance advantages
Multi-frequency receivers show clear resilience benefits
Conservative detection philosophies protect against sophisticated spoofing

But gaps remain:

Many deployed receivers lack modern anti-interference capabilities
Timing infrastructure often relies on single-source GNSS
Authentication adoption is slower than threat evolution
Integration testing rarely includes realistic interference scenarios

What Comes Next

Jammertest has become an annual fixture, with each year bringing more complex scenarios and broader participation. The 2025 results will shape:

Procurement requirements for critical infrastructure
Receiver development roadmaps at major manufacturers
Certification standards for safety-critical applications
Policy discussions about GNSS backup mandates

For those building or operating systems that depend on GNSS, the message is clear: test under realistic interference, demand multi-layer protection, and never assume signals are genuine.

The invisible infrastructure that keeps our world synchronized is under active attack. Jammertest 2025 showed both the severity of the threat and the viability of the defense. The question now is implementation speed.

TL;DR

Jammertest 2025 in Arctic Norway tested ~100 interference scenarios against GNSS receivers from major manufacturers
Coherent spoofing is the scariest threat—receivers that detected it and entered no-fix state performed better than those that followed fake trajectories
Septentrio’s AIM+ maintained centimeter accuracy under chirp jamming while competitors showed meter-level errors
Galileo OSNMA successfully authenticated signals and detected spoofing in real-world conditions
Time spoofing proved devastating—one receiver showed time 3 minutes in the past, catastrophic for finance/telecom
Multi-frequency, authenticated receivers with INS integration represent current best practice
100 TB of data now available at ESA for industry analysis