7.2 – Operating Without GPS: GNSS Denial as the New Baseline. A technical perspective from our technological partner TimTec.
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One of the most important shifts emerging from the workshop is the need to reconsider a fundamental assumption: GPS availability can no longer be taken for granted.
For years, GNSS has been treated as a stable and reliable enabler, underpinning navigation, targeting, synchronization, and command and control. This assumption is no longer valid.
The reality is that GPS denial—whether through jamming or spoofing—is not an exceptional condition, but an increasingly common feature of the battlefield. Systems that depend on uninterrupted GNSS access are therefore inherently vulnerable. This has direct implications for unmanned systems.
Drones rely heavily on positional awareness. Without it, their ability to navigate, coordinate, and execute missions degrades rapidly. However, the key takeaway from this session is not that GPS denial is a problem. It is that it must be treated as a design condition.
7.2.1 From Dependence to Resilience
Understanding GNSS is important, but the operational implication is simple: it is a low-power, easily disruptable signal. The frequencies used are inherently vulnerable to interference, and even relatively unsophisticated actors can degrade or deny access to reliable positioning. Two primary threats define this environment.
The first is jamming, which increases noise to the point where the signal becomes unreadable. The second is spoofing, which is more subtle and potentially more dangerous, as it feeds false positional data to the system without interrupting the signal itself. The operational effect is clear: a drone may not simply stop working—it may continue operating incorrectly.
This distinction is critical. A system that fails is a problem. A system that provides wrong data is a much more dangerous one.
7.2.2 Detection Is Not Enough
The first step in operating under GNSS denial is detection. Changes in signal strength, unexpected positional shifts, or inconsistencies in movement patterns can indicate interference. These indicators allow systems to recognize that GPS data is no longer reliable.
However, detection alone does not solve the problem. Once GNSS is denied or compromised, the system must be able to continue operating. This is where the discussion moves from awareness to resilience.
7.2.3 Navigation Without GPS
What emerges clearly is that there is no single alternative to GPS. Instead, resilience is achieved through sensor fusion.
Inertial navigation provides the first layer. Using accelerometers, gyroscopes, and magnetometers, it allows a system to estimate position and movement independently. However, this solution is inherently imperfect. Over time, errors accumulate, and the system begins to drift. To compensate for this, additional inputs are required.
Vision-based systems provide a second layer. By analysing images and tracking features in the environment, drones can estimate movement relative to the ground. Techniques such as optical flow allow the system to calculate translation and rotation, effectively reconstructing movement even in the absence of external signals.
More advanced approaches introduce semantic understanding. By recognizing patterns, terrain features, and environmental structures, systems can localize themselves and correct drift. This represents a significant step toward autonomy, allowing drones to operate in complex environments even under heavy interference.
Other methods, such as horizon detection or the use of terrain maps, further reinforce this capability, particularly in mountainous environments where terrain features are pronounced and can be exploited for navigation.
What emerges is not a replacement for GPS, but a layered system in which multiple sensors compensate for each other.
7.2.4 The Cost of Resilience
However, this resilience comes at a cost. Each additional sensor increases complexity, power consumption, and cost. It also introduces new requirements in terms of calibration, processing power, and integration. Systems become more capable, but also more demanding.
This creates a fundamental trade-off. Low-cost, expendable drones can be produced in large numbers, but have limited resilience. More advanced systems can operate in denied environments, but are fewer, more expensive, and more complex to sustain.
This tension reflects a broader challenge already highlighted in previous sections: the balance between mass and capability.
7.2.5 Implications for Mountain Warfare
In mountain environments, these challenges are amplified. Terrain interferes with satellite visibility, reducing signal quality even in uncontested conditions. Valleys, ridgelines, and dense vegetation create natural obstacles that degrade GNSS performance. When combined with deliberate jamming or spoofing, this results in environments where GPS may be unreliable or unavailable for extended periods.
At the same time, terrain provides an opportunity. Distinct geographical features—ridges, slopes, horizons—can be used as reference points for alternative navigation methods. Systems that are able to exploit these features can achieve a level of resilience that would not be possible in more uniform environments.
This reinforces a key idea: Mountain Warfare does not only complicate the problem. It also provides part of the solution.
7.2.6 Conclusion
GNSS denial fundamentally changes the way unmanned systems must be designed and employed. It is no longer sufficient to assume availability and build redundancy around it. Instead, systems must be conceived from the outset to operate without it.
GPS is no longer a guarantee. It is an advantage—when available. Operational effectiveness therefore depends on the ability to combine multiple navigation methods, accept limitations, and adapt employment accordingly.
GNSS denial illustrates one specific aspect of a broader operational reality: modern unmanned systems do not merely operate in difficult terrain, but in a battlespace where the entire electromagnetic domain is contested. Loss of navigation is therefore not an isolated technical problem; it is one manifestation of a wider struggle over connectivity, control, and information.
To understand the full implications, the discussion must move beyond positioning alone and examine how systems maintain mission continuity when the spectrum itself becomes unstable. The next section expands the focus accordingly, addressing electromagnetic resilience as a whole and exploring how communications, autonomy, swarm behaviour, and deconfliction must be rethought in mountain warfare.
7.2 – Operating Without GPS: GNSS Denial as the New Baseline. A technical perspective from our technological partner TimTec.
One of the most important shifts emerging from the workshop is the need to reconsider a fundamental assumption: GPS availability can no longer be taken for granted.
For years, GNSS has been treated as a stable and reliable enabler, underpinning navigation, targeting, synchronization, and command and control. This assumption is no longer valid.
The reality is that GPS denial—whether through jamming or spoofing—is not an exceptional condition, but an increasingly common feature of the battlefield. Systems that depend on uninterrupted GNSS access are therefore inherently vulnerable. This has direct implications for unmanned systems.
Drones rely heavily on positional awareness. Without it, their ability to navigate, coordinate, and execute missions degrades rapidly. However, the key takeaway from this session is not that GPS denial is a problem. It is that it must be treated as a design condition.
7.2.1 From Dependence to Resilience
Understanding GNSS is important, but the operational implication is simple: it is a low-power, easily disruptable signal. The frequencies used are inherently vulnerable to interference, and even relatively unsophisticated actors can degrade or deny access to reliable positioning. Two primary threats define this environment.
The first is jamming, which increases noise to the point where the signal becomes unreadable. The second is spoofing, which is more subtle and potentially more dangerous, as it feeds false positional data to the system without interrupting the signal itself. The operational effect is clear:
a drone may not simply stop working—it may continue operating incorrectly.
This distinction is critical. A system that fails is a problem. A system that provides wrong data is a much more dangerous one.
7.2.2 Detection Is Not Enough
The first step in operating under GNSS denial is detection. Changes in signal strength, unexpected positional shifts, or inconsistencies in movement patterns can indicate interference. These indicators allow systems to recognize that GPS data is no longer reliable.
However, detection alone does not solve the problem. Once GNSS is denied or compromised, the system must be able to continue operating. This is where the discussion moves from awareness to resilience.
7.2.3 Navigation Without GPS
What emerges clearly is that there is no single alternative to GPS. Instead, resilience is achieved through sensor fusion.
Inertial navigation provides the first layer. Using accelerometers, gyroscopes, and magnetometers, it allows a system to estimate position and movement independently. However, this solution is inherently imperfect. Over time, errors accumulate, and the system begins to drift. To compensate for this, additional inputs are required.
Vision-based systems provide a second layer. By analysing images and tracking features in the environment, drones can estimate movement relative to the ground. Techniques such as optical flow allow the system to calculate translation and rotation, effectively reconstructing movement even in the absence of external signals.
More advanced approaches introduce semantic understanding. By recognizing patterns, terrain features, and environmental structures, systems can localize themselves and correct drift. This represents a significant step toward autonomy, allowing drones to operate in complex environments even under heavy interference.
Other methods, such as horizon detection or the use of terrain maps, further reinforce this capability, particularly in mountainous environments where terrain features are pronounced and can be exploited for navigation.
What emerges is not a replacement for GPS, but a layered system in which multiple sensors compensate for each other.
7.2.4 The Cost of Resilience
However, this resilience comes at a cost. Each additional sensor increases complexity, power consumption, and cost. It also introduces new requirements in terms of calibration, processing power, and integration. Systems become more capable, but also more demanding.
This creates a fundamental trade-off. Low-cost, expendable drones can be produced in large numbers, but have limited resilience. More advanced systems can operate in denied environments, but are fewer, more expensive, and more complex to sustain.
This tension reflects a broader challenge already highlighted in previous sections: the balance between mass and capability.
7.2.5 Implications for Mountain Warfare
In mountain environments, these challenges are amplified. Terrain interferes with satellite visibility, reducing signal quality even in uncontested conditions. Valleys, ridgelines, and dense vegetation create natural obstacles that degrade GNSS performance. When combined with deliberate jamming or spoofing, this results in environments where GPS may be unreliable or unavailable for extended periods.
At the same time, terrain provides an opportunity. Distinct geographical features—ridges, slopes, horizons—can be used as reference points for alternative navigation methods. Systems that are able to exploit these features can achieve a level of resilience that would not be possible in more uniform environments.
This reinforces a key idea: Mountain Warfare does not only complicate the problem. It also provides part of the solution.
7.2.6 Conclusion
GNSS denial fundamentally changes the way unmanned systems must be designed and employed. It is no longer sufficient to assume availability and build redundancy around it. Instead, systems must be conceived from the outset to operate without it.
GPS is no longer a guarantee. It is an advantage—when available. Operational effectiveness therefore depends on the ability to combine multiple navigation methods, accept limitations, and adapt employment accordingly.
GNSS denial illustrates one specific aspect of a broader operational reality: modern unmanned systems do not merely operate in difficult terrain, but in a battlespace where the entire electromagnetic domain is contested. Loss of navigation is therefore not an isolated technical problem; it is one manifestation of a wider struggle over connectivity, control, and information.
To understand the full implications, the discussion must move beyond positioning alone and examine how systems maintain mission continuity when the spectrum itself becomes unstable. The next section expands the focus accordingly, addressing electromagnetic resilience as a whole and exploring how communications, autonomy, swarm behaviour, and deconfliction must be rethought in mountain warfare.