As military and autonomous platforms increasingly operate in contested environments, resilient Position Navigation & Timing (PNT) depends on more than GNSS alone. Jean-François Jourdas explains why tightly coupled navigation architectures are becoming essential.

Q: GNSS and inertial navigation have worked together for decades. What has changed?

A: Autonomous platforms increasingly operate where GNSS signals may be jammed, spoofed or unavailable. The challenge is no longer just accurate positioning but maintaining trusted PNT throughout the mission. This is driving tightly coupled multi-sensor navigation architectures.

Q: Many suppliers are offering solutions that combine GNSS and inertial navigation. What distinguishes modern architectures from previous approaches?

A: Modern architectures are no longer built around a simple GNSS receiver with inertial backup. They combine robust, trusted GNSS reception with advanced inertial navigation and sensor fusion. While some solutions focus primarily on either GNSS hardening or GNSS-free navigation, our approach addresses both challenges simultaneously: protecting access to trusted GNSS data against jamming and spoofing, while providing a resilient fallback based on inertial and multi-sensor fusion technologies. This ensures both accuracy and continuity in contested environments.

Q: Is inertial navigation only useful when GNSS is unavailable?

A: No. Inertial sensors continuously enhance navigation by supporting GNSS signal tracking and validating GNSS measurements. This enables faster recovery after signal loss -such as during maneuvers or brief jamming episodes – and improves anti-jamming and anti-spoofing performance.

Q: How important are software and sensor-fusion algorithms today?

A: Integrating multiple data and information sources through software is one of the most cost-effective ways to deliver resilient PNT solutions.

As operational threats evolve rapidly, navigation systems must evolve with them. Hardware cannot always change at the same pace, making a modular and upgradeable software architecture essential for introducing new capabilities as customer needs evolve.

Q: What will resilient navigation look like in ten years?

A: Future resilient PNT will increasingly rely on collaboration between platforms. By sharing navigation information and observations, connected systems will improve the accuracy and resilience of the entire network. Alternative navigation technologies – including visual navigation, MagNav, LEO-PNT and Signals of Opportunity – will also become increasingly mature, providing additional sources of positioning information. AI will complement this approach by intelligently combining GNSS, inertial sensors and alternative navigation sources to deliver the most reliable PNT solution.

Q: Is this vision already becoming reality?

A: Absolutely. These principles are already implemented in Safran Electronics & Defense’s DRAGN™, which combines tightly coupled GNSS, inertial navigation and advanced sensor fusion to deliver trusted navigation today while remaining ready for future capabilities.