Assured PNT: Delivering Resilient Positioning, Navigation, and Timing for Defence Systems
What is A-PNT?
Every platform, from ground vehicles to naval vessels, aircraft, and uncrewed systems, depends on accurate and resilient PNT to operate effectively. Assured PNT (A-PNT) brings together technologies that enable forces to navigate, communicate, and employ surveillance, targeting and engagement systems in all environments.
Historically, Global Navigation Satellite Systems (GNSS), such as the US-developed Global Positioning System (GPS), provided much of this capability. However, the vulnerability of GNSS to jamming and spoofing has been made abundantly clear by recent conflicts, most notably in Ukraine.
The lesson is simple: assured PNT is no longer optional; it is essential.
The sole reliance on GNSS for PNT is now recognised as a systemic weakness. GPS signals for instance can be jammed with relative ease or spoofed by transmitting false signals.
The extent of the issue is clear in Eastern Europe, where thousands of daily interference incidents are reported by civilian aircraft – one of the most recent involving EU President Ursula von de Leyen. For defence organisations, where assured positioning and synchronised timing underpin communications, targeting, and situational awareness, the risks are severe.
What’s the traditional approach to PNT?
Every defence system that captures or processes data is dependent on precise timing and timing synchronisation.
Whether it is a Radar utilising multiple signal processors, a Sonar Array correlating acoustic data, or an Electronic Warfare system analysing radio frequency spectrum, without synchronisation the system fails.
Timing source(s) and synchronisation have typically been implemented using proprietary approaches, developed by individual equipment manufacturers.
Proprietary timing approaches create vendor lock-in and complicate reconfiguration of field units or block it all together. System life cycles can then be compromised. As part of the drive toward open systems architectures, standards such as the Open Group Sensor Open Systems Architecture (SOSA®) Consortium were introduced to address this issue by collaborating with industry and government.
The VITA65 OpenVPX standard defines a specific set of rules, called the timing slot profile, for when and where certain signals should occur within a system. The SOSA initiative is pushing for all manufacturers to adopt this exact same timing slot profile so that different parts from different companies can easily work together.
Concurrent’s approach to A-PNT – PR A11
Concurrent’s contribution to this shift is PR A11/6sd-RCx, a 3U VPX-based product that is seeing growing success in this area.
A SOSA-aligned Plug In Card (PIC), PR A11 provides a comprehensive solution for assured PNT that goes far beyond conventional timing cards. Its modular design allows for flexibility in configuration, enabling customers to tailor it to specific applications while retaining interoperability and open standards compliance.
PR A11 integrates multiple technologies to deliver assurance. It incorporates a multi-constellation, multi-frequency GNSS receiver with anti-jam and anti-spoofing features, a multi axis inertial measurement unit (known as an IMU), an odometer for land applications, and a chip-scale atomic clock (CSAC).
These elements are brought together through a Kalman filter algorithm, which compares trusted historical data against current sensor inputs to validate accuracy.
For example, when the GNSS data becomes unreliable, the system uses the inertial and odometer data to regenerate accurate position and navigation information. This process ensures continuity of service, even in contested environments where GNSS is compromised and has been externally validated on a vehicle platform.
The modularity of PR A11 provides additional advantages. Customers can select a timing-only configuration for platforms such as naval vessels, where multiple navigation systems are already present but precise timing remains critical.
PR A11 is a closed system therefore customers cannot integrate their own modules. This design choice means it does not include an M-Code receiver, which prevents it from falling under strict ITAR export controls.
Simple, Reliable System Timing with PR A11
PR A11 is designed to serve as the system's central, standardised Timing PIC, offering a robust foundation for all precision synchronisation needs. A key benefit of this approach is the ability to easily manage the system's entire timing architecture.
PR A11 facilitates this control by providing Software (SW) configurable timing frequencies that can be distributed to multiple downstream payload PICs. This flexibility ensures that various components, even those with diverse operational clock requirements, can be driven and synchronised from a single, reliable source.
For highly accurate synchronisation, PR A11 supports IEEE 1588 Precision Time Protocol (PTP) grandmaster functionality. This capability is vital for modern sensor architectures, ensuring time-stamping accuracy across the network. The timing signals themselves can be distributed using resilient and flexible physical interfaces, specifically VITA 67 co-axial and/or Ethernet connections.
The system's adaptability is further enhanced by its software-configurable timing and navigation elements. This critical feature allows the exact same hardware to be deployed across multiple platforms, reducing logistical complexity and development costs.
To maintain exceptional accuracy even in challenging operational environments, PR A11 leverages a CSAC. The CSAC enables high precision timing with excellent holdover performance, which is essential for operations in GNSS (Global Navigation Satellite System) denied areas where continuous satellite signal reception is impossible.
The adoption of PR A11 is strongly supported by its SOSA alignment. This adherence to an open standard provides significant ecosystem benefits, including easier midlife upgrades/updates and the prevention of vendor lock-in, ensuring long-term flexibility and cost efficiency for the user.
Made in Britain
Another point of differentiation is sovereignty. PR A11 – like many of Concurrent’s solutions – can be sourced from either our US or UK facilities for customers concerned about security of supply and sovereign capability, this is a significant advantage.
In an environment where supply chains are under scrutiny and reliance on foreign technology is increasingly viewed as a vulnerability, sovereign solutions provide both assurance and strategic value.
The future of assured PNT will likely be defined by modularity, interoperability, and resilience. As open standards become entrenched across defence procurement, the ability to integrate timing and navigation cards from multiple vendors into common architectures will reduce cost, increase competition, and accelerate innovation.
For Concurrent, PR A11 is not just a product but a platform that demonstrates how assured PNT can be delivered in a flexible, standards-based manner.
Conclusion
In summary, Positioning, Navigation, and Timing is a cornerstone capability for defence, underpinning virtually every mission-critical system. The vulnerability of GNSS has made the case for assured PNT compelling, and the adoption of open standards has created an opportunity for new, interoperable solutions.
Concurrent’s PR A11 PNT card embodies these principles, offering modularity, assurance, and sovereignty in a SOSA-aligned VPX format. As militaries worldwide adapt to contested and complex operating environments, assured PNT will be critical, and Concurrent is positioned to meet that demand with market-leading solutions.