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

New Cesium-Less ePRTC Solution to Provide Timing for Homeland Critical Infrastructure
Nino De Falcis and Lisa Perdue, VIAVI Solutions
Location: Ballroom C
Date/Time: Monday, Jun. 1, 5:05 p.m.

For more than two decades, traditional Cesium atomic clocks have been used in combination with GPS/GNSS grandmasters to meet the international ITU-T G.8272.1 standard. This standard specifies that an Enhanced Primary Reference Time Clock (ePRTC), when operating in holdover mode due to GPS loss or disruption, must maintain a short-term drift of less than 30?ns at holdover entry and a long-term drift of less than 100?ns over 14?days, all traceable to UTC.
The new Cesium-less technology has been successfully validated across a range of live-sky defense and commercial jamming/spoofing environments and has been integrated into VIAVI’s SecurePNT?6200 product series. It maintains 100?ns accuracy during GNSS-denied conditions indefinitely through the resilient altGNSS?GEO-L service. The solution incorporates an augmented VIAVI?SecureTime?GEO anti-jamming antenna and an enhanced GNSS anti-spoofing antenna capable of receiving eGNSS?GEO service with GPS/GNSS?NMA authentication for spoofing detection and mitigation.
Unlike conventional GPS/GNSS signals, which can be easily degraded by low-power interference, the Cesium-less ePRTC leverages an exclusive GPS/GNSS-independent GEO-L service featuring encrypted L-band signals transmitted from geostationary satellites. This approach provides a resilient and continuous timing reference for the internal Rubidium holdover oscillator and supports smooth multi-orbit source switchover, even when primary GNSS signals are jammed, spoofed, or subject to sophisticated meaconing attacks.
The Cesium-less ePRTC also resolves several operational and logistical challenges inherent to Cesium-based clocks, including sensitivity to shock, lengthy multi-stage startup processes, export licenses, GNSS learning periods of up to 40?days, and stringent shipping and storage protocols. Additionally, Cesium tubes typically require replacement every seven years, and their disposal is classified as hazardous due to material content.
With its unprecedented affordability, the Cesium-less ePRTC360+ enables wide deployment beyond the network core, enhancing end-to-end synchronization resilience and holdover reliability through meshed PTP network interconnections. This distributed robustness provides critical support for homeland infrastructure, particularly under local or regional jamming and spoofing scenarios.
The session will present live test results, including characterization of the directional GEO-L antenna's resilience against GNSS jamming signals transmitted from multiple orientations, evaluation of in-band interference rejection, and demonstration of the system's seamless switchover from GNSS to GEO-L timing sources. Extended timing accuracy measurements will compare the system's 1PPS output against a reference source over a multi-week period to verify compliance with the 100 ns holdover requirement.

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