Previous Abstract Return to Session F4

Session F4: Application/Impact of PNT Technologies in the Homeland Critical Infrastructure

Multi-Source Resilient Time for Critical Infrastructure
Marvin J. Rozner, VIAVI Solutions
Location: Ballroom C
Alternate Number 1

Critical infrastructure systems increasingly depend on precise and continuous time to support safe and reliable operation. Electric power generation and distribution, telecommunications networks, financial trading platforms, data centers, transportation systems, and public safety communications all rely on accurate timing for synchronization, protection, logging, and control. Today, the majority of these systems derive time from the Global Positioning System (GPS), creating a common-mode vulnerability to jamming, spoofing, interference, and cyber-physical attack.
This paper presents a practical, multi-source approach to resilient timing for fixed and temporarily static critical infrastructure sites, with emphasis on time-only applications where position and navigation are not required. The approach prioritizes timing sources that are operationally independent of GNSS-based timing reception, including geostationary Earth orbit (GEO) and low Earth orbit (LEO) satellite-based alternative timing services, high-performance local oscillators capable of maintaining accurate time through extended disruptions, and optional auxiliary time sources. These independent layers, combined with long-term oscillator holdover, form the foundation of the proposed resilience strategy.
A patented multisource GPS RF transcoder mechanism converts trusted timing inputs into a standard GPS-compatible radio-frequency output, enabling a plug-and-play upgrade of legacy GPS-dependent equipment to continue operating without modification during GPS disruption. The system continuously monitors all timing inputs, assesses trust and performance, and automatically selects the most reliable source. Seamless switching and precision holdover ensure continuity such that short- and medium-duration, and performance-aligned long-duration service interruptions do not result in observable timing outages at downstream equipment.
While most U.S. critical infrastructure timing systems rely exclusively on GPS, additional Global Navigation Satellite System (GNSS) constellations can provide a practical initial auxiliary layer of resilience for many existing deployments. In the architecture described, multi-constellation GNSS is treated as an augmentation layer, improving robustness against localized or constellation-specific issues, while independent GEO- and LEO-based timing services and oscillator holdover provide the assurance required to withstand wide-area or prolonged GNSS disruption.
The approach supports national timing resilience objectives by enabling layered and complementary timing strategies that improve continuity of operations during GPS or GNSS disruption or degradation. System capabilities are evaluated against emerging resilience frameworks, including IEEE P1952, with explicit mapping to Detect, Recover, Resist, Withstand, and Verify functions. Results from laboratory testing, operational deployments, and field trials—using commercially available multisource timing platforms including the VIAVI SecurePNT® 6200 series—illustrate achievable accuracy, holdover behavior, and end-user observable availability. The paper concludes with lessons learned and a discussion of future enhancements, including improved accuracy, additional timing layers, and next-generation oscillators.

Previous Abstract Return to Session F4