understanding GNSS-Denied Navigation
Operating Without Satellite Signals
In modern military operations, reliable navigation can be the difference between mission success and failure. But what happens when satellite-based navigation suddenly becomes unavailable?
GNSS-denied navigation refers to the ability to navigate, hold position, and complete missions without dependable satellite signals from Global Navigation Satellite Systems (GNSS). In these environments, forces must rely on alternative sensors, onboard intelligence, and resilient flight control systems to maintain operational control.
This blog post explores the reality of GNSS-denied environments and how advanced Unmanned Aerial Systems (UAS) like the RQ-35 Heidrun ensure mission continuity even under the most intense electronic warfare conditions.
Key Facts: GNSS-Denied Navigation
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GNSS-denied environments
occur when GPS or satellite signals are blocked, jammed, or spoofed during military operations.
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Electronic warfare (EW)
tactics increasingly target GNSS to disrupt positioning, timing, and communication systems.
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Resilient UAVs
rely on multi-sensor fusion and autonomous navigation to operate without satellite input.
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The RQ-35 Heidrun
is combat-proven to maintain mission performance in GNSS-denied and electronically contested environments.
Understanding GNSS and Its Role in Modern Navigation
Global Navigation Satellite Systems (GNSS) - such as GPS, Galileo, or GLONASS - provide the foundation for global positioning, navigation, and timing.
For military forces, GNSS ensures precise coordination, synchronized operations, and accurate targeting across land, sea, and air. From coordinating ISR missions to aligning artillery fire, GNSS is a critical enabler of modern warfare.
When those signals are disrupted, the result isn’t just inconvenience but operational vulnerability.
What Does “GNSS-DenieD" Mean?
A GNSS-denied environment is any area where satellite navigation signals are jammed or intentionally manipulated. In other words, when GPS and other positioning systems cannot be trusted.
Common causes of GNSS-denial:
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Signal blockage – terrain, urban canyons, or heavy cover prevent signal reception.
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Jamming – hostile actors use powerful transmitters to overpower satellite signals.
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Spoofing – false signals mislead systems into calculating incorrect positions.
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Contested environments – active electronic warfare and cyber-attacks degrade connectivity.
Risks of GNSS disruption
When GNSS fails, situational awareness collapses. Operators lose reliable coordinates, mission timelines suffer, and ISR data may become unreliable. All these factors increase the risk of human and operational error.
The Military Challenge of GNSS-Denied Environments
Modern warfare has shown that GNSS denial is not hypothetical but a daily reality.
Lessons from Ukraine
The war in Ukraine has highlighted how electronic warfare now plays a decisive role on the battlefield. UAVs operating in contested airspace are constantly exposed to signal jamming and spoofing attempts. Those unable to maintain navigation integrity quickly become ineffective or, even worse, liabilities.
Forces using the RQ-35 Heidrun have shown that resilient UAS design and advanced navigation secure mission success, even in severe electronic interference.
Why UAVs Need GNSS-Denied Capabilities
Unmanned systems are especially vulnerable to GNSS disruption but they’re also the platforms most capable of adapting.
Vulnerability of drones to jamming
Without resilient navigation, drones lose position hold, stability, and route accuracy.
That can ground operations entirely or expose troops relying on aerial intelligence.
Importance of reusability and survivability
Forces need UAVs that not only survive in GNSS-denied conditions but can return with critical data intact.
Every mission must generate actionable intelligence, even under degraded signals.
Integration into C4I systems for resilience
Navigation resilience isn’t an isolated feature. It must integrate across C4I ecosystems, enabling operators to fuse data from multiple sensors, cross-verify coordinates, and maintain control even when primary systems fail.
The RQ-35 Heidrun is designed as a seamless component of this ecosystem, ensuring full interoperability and real-time data flow across all mission-critical platforms.
RQ-35 Heidrun: Built for GNSS-Denied Environments
The RQ-35 Heidrun was engineered precisely for these realities.
Designed and produced in Denmark, and combat-proven in Ukraine since 2022, the Heidrun combines robust hardware with intelligent software to sustain performance where others can’t.
RQ-35 Heidrun in contested spaces
RQ-35 Heidrun is built for operations where reliability matters more than ideal conditions.
It maintains navigation and control without GNSS access and continues to deliver ISR data even under jamming or spoofing.
With a compact, hand-launched design and long endurance, the system supports frontline units that need fast deployment and consistent performance in demanding environments.
Proven resilience under electronic warfare
The platform’s advanced flight controller and sensor fusion allow autonomous stability and return-to-home navigation without relying solely on satellite input, ensuring operators maintain mission control.
Modular design and continuous software updates
Through its modular architecture and ongoing software development, Sky-Watch continuously enhances the RQ-35’s ability to adapt to evolving EW threats, ensuring that operators retain tactical advantage in any signal environment.
Conclusion
GNSS-denied navigation is increasingly a reality on modern battlefields. Reliable systems that operate without satellite signals are essential.
The RQ-35 Heidrun and other resilient UAVs act as force multipliers, keeping operators informed, coordinating missions, and delivering critical intelligence even when GNSS is lost.
Frequently Asked Questions
Jamming occurs when hostile actors broadcast strong signals that overwhelm GNSS satellites, preventing systems from receiving accurate positions. Spoofing, on the other hand, sends false signals that trick the system into calculating incorrect positions. In short, jamming blocks, spoofing misleads.
The Heidrun relies on multi-sensor fusion and autonomous navigation. It combines data from internal sensors, such as inertial measurement units and visual references, to maintain course, position, and stability even when satellite signals are unavailable.
Operators may notice discrepancies between expected and actual positions, sudden signal loss, or unusual course deviations. Advanced system alerts and cross-verification of sensor data in the RQ-35 help identify these threats quickly.
Navigation resilience is fully integrated with C4I environments, allowing data from multiple sensors and platforms to be cross-verified. Even in GNSS-denied conditions, the system delivers reliable position and ISR data to command and control networks.
Yes. Operators need training on GNSS limitations, recognizing signs of jamming and spoofing, and leveraging the Heidrun’s autonomous capabilities. Controlled simulations in GNSS-denied environments are recommended to ensure mission effectiveness under real-world conditions.
