Resilient PNT Needs More Than Satellites

By Dr Eldar Rubinov

For decades, positioning, navigation and timing (PNT) has been delivered almost exclusively from space. Today, Global Navigation Satellite Systems (GNSS) remain the foundation of modern life, supporting location services on our phone apps as well as areas such as surveying, aviation, maritime operations, banking, power grids, and emergency response.

However, reliance on a single layer of satellite-based PNT is increasingly risky. PNT disruptions are no longer rare or theoretical. They are happening more frequently and with serious consequences. We are already seeing:

• Interference and disruptions affecting hundreds of flights and shipping voyages daily
• Software faults and system outages affecting global constellations
• Space weather events disrupting safety-of-life services
• Insider threats are happening in space and critical infrastructure
• Anti-satellite (ASAT) weapons and close proximity operations targeting space assets

Signals from 20,000 kilometres above Earth are inherently weak by nature. They are easy to block, deceive, or degrade, and when they fail, the impacts cascade far beyond navigation.

Building multi-layered resilience

Building and maintaining resilient PNT systems is now essential to the security and reliability of national infrastructure.

True resilience comes from using more than one source of position and time. By combining complementary systems rather than relying on satellites alone, services can continue even when one layer is disrupted.

Various complementary and alternative solutions are either already available or being developed, including:

• Low Earth Orbit (LEO) PNT offering stronger signals, authentication and frequency diversity
• Terrestrial broadcast systems providing wide-area coverage and remaining resilient when space-based services are affected
• GNSS-independent timing services, both space and terrestrial-based to protect critical infrastructures in times of GNSS outages
• Onboard inertial, gravity and magnetic navigation systems, including emerging quantum approaches, offering locally independent position and timing continuity
• Vision-based navigation that uses cameras to recognise features and map the surroundings, helping systems maintain performance in GPS-denied environments

The future is not about replacing satellites; it’s about strengthening and complementing them with terrestrial infrastructure, on-platform sensing, and authenticated services. Countries around the world are moving toward these layered architectures to reduce risk and ensure national resilience.

A shared responsibility

Image credit: Q-CTRL

Building resilience is not a task for government alone. It requires collaboration across the industry, operators and technology providers.

With so many technologies maturing in parallel at lightning speeds, it’s difficult to predict which approach will prove most effective. This is why collaborative testing, open evaluation and a focus on interoperability are essential to ensure diverse systems can operate together seamlessly rather than relying on a single solution.

What this means for Australia

For Australia, strengthening PNT resilience starts with understanding where its dependencies lie and investing in solutions that strengthen national systems.

This means going beyond GNSS-only reliance and developing complementary technologies that can operate independently when needed.

Just as importantly, it means turning promising technology into operational systems that are tested, validated and ready to support critical infrastructure and essential services.

FrontierSI’s upcoming report, PNT Threats & Trends in the Australian context, explores these technologies, gaps, and policy implications in more detail.

What layers or technologies should Australia be developing now to prepare for a more contested PNT environment? If this topic matters to you or your organisation, or if you have experience or insights to share, please reach out.

If you are interested in this topic, Dr Eldar Rubinov recently presented in the Australian Institute of Navigation Webinar Series, where he shared insights from Armouring the Clock, a project funded through the Defence Strategic Policy Grants Program. He explored how Australia can strengthen its navigation and timing systems through better coordination, stronger governance and emerging sovereign technologies.