VIAVI unveils Cesium‑free ePRTC360+ holdover clock for GNSS‑denied, critical‑infrastructure networks

VIAVI debuts Cesium‑free holdover clock for GNSS‑denied networks

VIAVI Solutions introduces the patent‑pending ePRTC360+, positioning it as the only Cesium alternative that meets the ITU‑T G.8272.1 ePRTC drift standard and delivers Cesium‑level holdover performance at far lower cost. The device records short‑term drift of under 30 nanoseconds when entering holdover and under 100 nanoseconds over 14 days, with all timing traceable to Coordinated Universal Time (UTC). VIAVI integrates the technology into its SecurePNT 6200 family to provide a full timing solution for networks that cannot rely solely on GNSS.

The ePRTC360+ is engineered to protect critical infrastructure — including power grids, transportation, aviation, public safety, 5G mobile networks and AI data centers — against jamming and spoofing threats. VIAVI says the system maintains 100 ns accuracy during GNSS‑denied events without time limits by combining the ePRTC holdover oscillator with its altGNSS GEO‑L service and augmented SecureTime GEO anti‑jamming and enhanced anti‑spoofing antennas. The GEO‑L approach uses encrypted, highly directional L‑band transmissions from geostationary satellites, reducing vulnerability to low‑power interference and enabling deployment across edge sites that previously could not justify Cesium clocks.

VIAVI reports that ePRTC360+ undergoes live‑sky testing in both defense and commercial jamming and spoofing environments and demonstrates robust performance for time‑sensitive applications. Doug Russell, senior vice‑president and general manager for Aerospace and Defense at VIAVI, says the device exceeds leading‑edge Cesium holdover performance while lowering total cost of ownership and easing compliance through built‑in UTC traceability and GNSS‑NMA authenticated eGNSS service for spoofing detection and mitigation. Field trials with commercial and defense operators show applicability for high‑precision synchronization across smart grids, autonomous transport, mission‑critical 5G slices and AI compute fabrics.

Showcasing broader product portfolio at MWC Barcelona

VIAVI announces a broad demonstration program at Mobile World Congress Barcelona 2026 (booth 5B18), where it presents more than 30 demos spanning AI data‑center validation, assured Position Navigation and Timing (APNT), non‑terrestrial network testing, and quantum‑safe communications. The company frames the exhibit around "domain convergence" of networks, AI, security, photonics and sensing and runs daily live digital twin demos at 4:00 PM CET.

The demonstrations involve over 20 partner organisations, including Ericsson, Nokia, AWS and NVIDIA, and emphasise VIAVI’s role in test, monitoring and assurance for resilient timing, high‑volume optical applications and mission‑critical communications. CTO Sameh Yamany says the program shifts testing from components to validating behaviour, trust and resilience at scale.