Last week, our Oscilloquartz team of network synchronization specialists headed to San Diego for the World Symposium on Timing and Synchronization (WSTS). There, we were able to share advancements that help make assured positioning, navigation and timing (aPNT) networks more resilient. 

aPNT refers to systems that provide trusted, accurate and robust PNT information under all conditions. These architectures are closely aligned with Department of Homeland Security (DHS) guidelines for achieving resilient PNT, particularly in the context of enhancing national resilience and security for critical infrastructure.

The more resilient, the better

Creating a robust aPNT solution involves overcoming the inherent vulnerabilities of the Global Navigation Satellite System (GNSS). Being reliant on one GNSS source alone means you’re dependent on a single point of failure. In a world of increasing cyberattacks, that’s unacceptable. To mitigate threats to GNSS availability and accuracy, aPNT networks employ various systems and technologies, including:

• Anti-jamming and spoofing technologies incorporated into GNSS receivers
• Multiple augmented GNSS grandmaster solutions
• Alternative primary sources of PNT information
• Atomic cesium solutions that provide holdover when GNSS is unavailable (note that the US government does not consider atomic clocks a standalone timing reference, so it can only augment a primary timing source, not replace it)

Exploring advanced aPNT solutions

At each of our WSTS sessions last week, we examined options for rendering aPNT architectures more reliable. In addition to discussing the utility of ePRTCs for providing extended timing and synchronization backup, my colleague Alon Stern’s talk, “Pushing the limits of assured PNT,” highlighted parametric holdover, a feature of the recently updated G.8272.1 standard that refers to the capability of a system to maintain accurate timing based on previously established parameters when an external time reference, such as GNSS or a network time server, becomes unavailable. Alon argued that current parametric holdover requirements don’t go far enough, and provided insights into research simulating the performance of cesium clocks to achieve 100 nanoseconds of accuracy for more than 100 days.

The session from Oscilloquartz associate VP, Alyona Diachenko, “Resilience of alternate PNT compared to traditional PNT systems,” concerned signals of opportunity (SoOp), space-based PNT and non-space-based PNT methods. SoOp is a catch-all term for acquiring PNT data from diverse sources not intended for navigation purposes. This helps operators gain an extra layer of backup in GNSS-denied environments. SoOp’s many potential sources include Wi-Fi, LTE and RF signals.

Creating a robust aPNT solution involves overcoming the inherent vulnerabilities of GNSS.

In my own talk, “Strategies for resilient synchronization of smart grids,”  Chris Cooper of Oakridge National Laboratories and I explained how multiple resiliency strategies are complemented by low-Earth orbit (LEO) satellites. These satellites augment smart grid PNT systems to ensure the reliability of operations under diverse conditions. Our dual source GNSS and LEO OSA 5405-S grandmaster, developed in partnership with Iridium®, can establish a secure link to LEO satellites in locations where GNSS signals are unreliable or non-existent, such as indoor environments or urban canyons. The technology is ideal for smart grid networks, which often require compact, scalable solutions able to interoperate with legacy technologies.

Ensuring reliability

Our 5405-S is just one of the technologies that make up our expanding lineup of advanced aPNT+™ solutions. Other solutions helping operators ensure robust aPNT delivery include our groundbreaking OSA 3350 SePRC optical cesium clock. The device leverages a technique we call optical pumping to provide accuracy to within 100 nanoseconds of Universal Coordinated Time (UTC) for a minimum of 45 days. This extended holdover capacity is crucial for bolstering the reliability of many mission-critical applications, including those present in utilities, finance and defense networks.

Enhanced protection of critical timing networks

Our participation at events like WSTS underscores our leadership in advocating for more robust assured PNT systems. By showcasing our aPNT+™ portfolio, we demonstrated our commitment to providing the most robust defense against the growing threat of cyberattacks. This plays a critical role in helping our customers and the broader industry understand the essential strategies for achieving dependable PNT redundancy and resilience in an efficient and cost-effective way.

We can’t wait to return to WSTS in 2025, where we’ll continue to lead discussions on the future of network synchronization and unveil further advancements in our aPNT+™ solutions.