Why navigation systems must evolve against GNSS spoofing

GNSS reception is facing growing threats from jamming and spoofing, and having a navigation system that doesn’t solely rely on satellite signals has become vital.

The Global Navigation Satellite System (GNSS) has long been the bedrock of modern positioning, navigation and timing (PNT).

From guiding autonomous vehicles to ensuring the precise synchronisation of global communication networks, GNSS signals are the silent workhorses enabling unprecedented levels of automation and efficiency.

Yet, beneath this reliability lies a growing, often underestimated vulnerability: GNSS spoofing.

Vital commercial sectors, from autonomous vehicles to global shipping, are dangerously dependent on unencrypted GNSS signals for positioning and timing. This reliance creates a significant, yet often underestimated, vulnerability to spoofing attacks that can cause significant physical and economic disruption.

In military situations, defence forces require a resilient PNT solution architected with the capability to detect and reject spoofing, while delivering precision navigation in GPS-denied or GPS-contested environments when it counts. Adversarial electronic attacks are no longer limited to brute-force jamming. Today, they are sophisticated, multi-layered assaults designed to create believable but false navigational guidance. For mission success in a contested environment, a simple anti-jam antenna is not enough.

Electronic protection, formerly known as electronic counter-countermeasures (ECCM), exists to provide precision in chaos. Electronic protection is an integrated set of capabilities designed to provide a multi-layered defence. The primary goal is to ensure the defence vehicle or platform can continue its mission despite operating in a hostile electromagnetic environment.

What is GNSS spoofing?

GNSS spoofing is the intentional transmission of counterfeit GNSS signals designed to deceive a receiver into calculating an incorrect position, velocity or time.

Unlike jamming, which merely blocks or disrupts signals, spoofing provides plausible, but false, data. This deception makes it particularly dangerous, as a system under attack might continue to operate, believing its PNT data is legitimate, while actually veering off course or operating with faulty timing.

Imagine a commercial airliner navigating through or even near GNSS-contested environments. A spoofing attack could subtly shift its perceived location, causing it to deviate from its intended path, risking collision, grounding or entry into restricted airspace.

Unfortunately, GNSS spoofing incidents (particularly in recent years) are well documented, highlighting the urgent need for robust anti-spoofing technology.

Engineers intimately understand that every component and data stream in a system is a potential point of failure or attack. The perceived infallibility of GNSS often leads to an oversight of its vulnerabilities.

A system that leverages the precision of GNSS could be rendered unsafe or ineffective by a relatively low-cost, unsophisticated spoofing device. This realisation drives the imperative for urgent change.

Why inertial navigation systems are the first line of defence

For many years, inertial navigation systems (INS) have been the backbone of reliable navigation in environments where GNSS is unavailable or unreliable — such as submarines, spacecraft or underground tunnels. Their core strength lies in their independence from external signals, using internal sensors (accelerometers and gyroscopes) to track changes in motion and orientation relative to a known starting point.

While an INS drifts over time, its short-term accuracy is exceptionally high. This characteristic makes it the perfect complement to GNSS. When integrated, a tightly coupled GNSS/INS system leverages the best of both worlds for long-term accuracy and global coverage of GNSS, combined with the high-rate, short-term precision, and most critically, immunity to external signal interference of the INS.

This combination is about resilience. When GNSS signals are jammed or spoofed, a robust INS can maintain accurate PNT data for significant periods, allowing the system to continue operating safely, initiate evasive manoeuvres, or transition to alternative navigation methods. This capability is paramount for engineers designing systems where a loss of PNT integrity is simply not an option.

Electronic protection as a defence imperative

The concept of simply integrating an INS with GNSS is a good start, but in today’s threat landscape, it’s no longer enough. The market now demands electronic protection — a comprehensive suite of capabilities integrated directly into the navigation system to actively detect, mitigate and recover from various forms of GNSS interference, including spoofing and jamming.

Understanding electronic protection as a distinct and vital market category is crucial for smarter processing and multi-layered defence strategies.

Building an electronic protection solution

Modern electronic warfare and commercial navigation demand a multi-layered, ‘defence-in-depth’ architecture that preserves navigational precision across the entire signal processing chain.

Unlike standard systems that only check for basic signal power anomalies, INS units with advanced electronic protection assess incoming GNSS signals for anomalies that indicate spoofing. This can include monitoring signal power variations, sudden changes in estimated position inconsistent with inertial data, unexpected satellite constellations, or inconsistencies across multiple GNSS frequencies. These anti-spoofing techniques aim to immediately identify and reject malicious signals, preventing the system from being led astray.

An effective electronic protection navigation system must integrate three critical capabilities:

• Robust RF front-end: This involves using multi-band GNSS receivers to maximise satellite visibility, as well as advanced anti-spoofing and anti-jamming filtering techniques to mitigate the impact of brute-force electronic attacks before they can corrupt the signal.
• Intelligent signal monitoring: Beyond simple jamming, the system must actively detect and reject sophisticated deception attacks. This requires real-time spoofing detection that constantly monitors signal integrity, cross-checks satellite data and identifies anomalies inconsistent with genuine GNSS transmissions.
• A high-performance inertial core: The source of precision is a coupled inertial navigation system (INS) and a fibre-optic gyroscope (FOG) for an independent, high-integrity source of position and attitude data. When the system detects jamming or spoofing, a sophisticated fusion of sensor inputs can reject the corrupted GNSS measurements and rely on this inertial holdover to bridge gaps in coverage and maintain precision until reliable signals return, ensuring continuous navigation in GPS denied or contested environments.

The time to build resilience is now

Commercial applications — from ensuring the safety of autonomous vehicles to the efficiency of global supply chains — are vulnerable, and the consequences of inaction are risky. Likewise, military missions and the lives of those involved depend on accurate PNT data at all times.

The evolution of navigation systems means embracing electronic protection as a core design philosophy. It means deploying robust, multi-layered defences that integrate high-performance INS solutions with advanced anti-spoofing and anti-jamming capabilities.

Conclusion

The threat of GNSS spoofing is not a distant or theoretical risk — it is a present and escalating reality affecting both commercial and military operations worldwide. As adversaries grow more sophisticated and our dependence on accurate PNT data deepens, the margin for complacency narrows to zero.

Integrating electronic protection into navigation system design is no longer optional; it is a fundamental engineering imperative. Those who act now to build resilient, multi-layered GNSS/INS solutions will be best positioned to operate safely and effectively in an increasingly contested electromagnetic environment.

Image credit: iStock.com/mechanick