Why APNT Matters
Modern operations in defense, military, and maritime environments depend on precise positioning, navigation, and timing. GPS and GNSS have been the backbone of these services for decades, but they are increasingly vulnerable. The signals are inherently weak and can be easily overwhelmed by jamming and spoofing attacks to inject false signals and mislead receivers. Even without hostile interference, GPS performance suffers in urban canyons, at high latitudes, or during operations in contested areas. For mission critical systems and commercial maritime operators, losing trusted timing and positioning is unacceptable.
Assured PNT (A-PNT) via Iridum PNT addresses the problem by providing resilient, cryptographically authenticated, and redundant services that continue to operate even in GPS or GNSS-denied environments.
Iridium PNT
Ground Control’s A-PNT solutions are built on Iridium’s Positioning, Navigation and Timing service, Iridium PNT. The constellation of 66 Low Earth Orbit (LEO) satellites provides overlapping global coverage, including the polar regions, where GPS performance is more vulnerable to ionospheric disruptions and poor geometry.
Unlike GNSS satellites in Medium Earth Orbit (MEO), Iridium satellites transmit PNT signals that are approximately 1,000 times stronger than GPS signals, allowing them to penetrate buildings and other hard to reach areas with only a receiver and a small antenna.
This enhanced signal strength makes A-PNT particularly valuable in urban canyons, indoor environments, and other challenging conditions where GNSS signals may be obstructed. The signal is also stronger, more robust against interference, and far more difficult to jam or spoof.
By delivering A-PNT signals independently, but alongside GPS and GNSS, Iridium creates an independent and resilient timing and navigation layer. For maritime shipping, defense operations, and other critical missions, this means trusted positioning and synchronization anywhere on Earth, even under deliberate electronic attack.
Resilience Against Jamming and Spoofing
Jamming and spoofing are growing threats to global navigation systems in maritime, military, and defense industries, but A-PNT provides a layered defense. The stronger signal of Iridum PNT and LEO downlink increases resistance to jamming, and even if interference is attempted, cryptographic authentication allows Ground Control devices to reject counterfeit signals.
When GNSS is available, A-PNT devices can operate in hybrid mode, blending sources for maximum accuracy. When GNSS is unavailable, the system falls back on Iridium PNT alone – without losing continuity of service.
Cryptographic Integrity
Satellite proximity to the Earth and signal strength alone are not enough to secure PNT, so Iridium PNT service incorporates cryptographic authentication to protect against spoofing and tampering. Every navigation and timing message is digitally signed, and Ground Control devices verify the integrity of those signatures before using the data. Unauthorized or falsified signals are rejected, ensuring that systems operate only on trusted information.
This security model extends through the entire A-PNT chain. Devices such as the RockSTAR APNT and RockBLOCK APNT are equipped with verification logic that ensures data cannot be manipulated in transit. Authorized users are provisioned with secure keys that allow them to authenticate signals. This design prevents unauthorized or falsified signals from being accepted, further enhancing the security and reliability of positioning, navigation, and timing (PNT) data in environments where traditional GNSS signals may be compromised.
System Architecture
The A-PNT architecture is designed for resilience and seamless integration into existing IT and operational networks. At its foundation is the Iridium satellite constellation, which continuously broadcasts navigation and timing data as part of its communications service. The constellation is supported by a secure ground network that maintains global synchronization with atomic time standards and manages the distribution of cryptographic keys.
On the user side, Ground Control’s A-PNT-enabled devices receive and process this data. The RockSTAR APNT is a ruggedized handheld unit suitable for field deployment, while the RockBLOCK APNT is a mounted unit designed for integration into ships and vehicles. These devices provide trusted position and timing information directly into command and control systems, electronic chart display systems and existing IT infrastructure. Because the Iridum PNT-enabled devices can operate seamlessly alongside GPS, they provide both redundancy and resilience without requiring major changes to existing infrastructure.
Applications in Defense and Maritime
For maritime shipping, our A-PNT devices output standard NMEA position data, enabling integration with a wide range of existing navigation systems, ensuring you retain accurate data even when GPS signals are degraded or spoofed in congested sea lanes.
Defense forces benefit from secure blue-force tracking and timing synchronization across C4ISR (Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance) platforms, maintaining operational coherence under hostile electronic warfare conditions.
Expeditionary forces can deploy rugged, wearable A-PNT devices to provide assured positioning and timing in areas with no supporting infrastructure.
Why Operators and Leaders Should Care
For commercial maritime operators and military and defense leaders, A-PNT is not just about navigation. Trusted timing underpins secure communication protocols and cryptographic key exchanges. Resilient timing also ensures that systems remain in sync – an essential requirement for command, control, and critical communications. By integrating Ground Control’s A-PNT devices, commercial maritime operators and military and defense leaders add a layer of cyber resilience to their networks, ensuring that operations remain reliable in contested, degraded, or GPS-denied environments.
Next Steps
Ground Control provides A-PNT technology in a practical, deployable form through the RockSTAR APNT and RockBLOCK APNT devices. These platforms extend Iridium’s PNT service into handheld and mounted solutions for military and defense, and commercial shipping applications. To learn more about how APNT can support your operations or your mission, explore our product pages, connect with our engineering team, or download our defense brochure for a deeper dive into the APNT devices and applications.
Talk to an expert
We work with organizations across defense, utilities, maritime, and more to design secure, resilient, and future-ready connectivity strategies.
Get in touch to discuss your tracking challenges and opportunities; either complete the form or email hello@groundcontrol.com and we’ll respond within one working day.